Archive for March 21st, 2008

Prozac-makers taking Prozac

BBC, 2/26/08: 

Woman taking pill (Photo: SPL/file)
Anti-depressant prescription rates have soared
 

New generation anti-depressants have little clinical benefit for most patients, research suggests.A University of Hull team concluded the drugs actively help only a small group of the most severely depressed.

Marjorie Wallace, head of the mental health charity Sane, said that if these results were confirmed they could be “very disturbing”.

But the makers of Prozac and Seroxat, two of the commonest anti-depressants, said they disagreed with the findings.

A spokesman for GlaxoSmithKline, which makes Seroxat, said the study only looked at a “small subset of the total data available”.

Reviewed data

And Eli Lilly, which makes Prozac, said that “extensive scientific and medical experience has demonstrated it is an effective anti-depressant”.

There seems little reason to prescribe anti-depressant medication to any but the most severely depressed patients
Professor Irving Kirsch
University of Hull
 

Alan Johnson, the Health Secretary, has announced that 3,600 therapists are to be trained during the next three years in England to increase patient access to talking therapies, which ministers see as a better alternative to drugs.

Patients are strongly advised not to stop taking their medication without first consulting a doctor.

The researchers accept many people believe the drugs do work for them, but argue that could be a placebo effect - people feel better simply because they are taking a medication which they think will help them.

In total, the Hull team, who published their findings in the journal PLoS Medicine, reviewed data on 47 clinical trials.

They reviewed published clinical trial data, and unpublished data secured under Freedom of Information legislation.

They focused on drugs which work by increasing levels of the mood controlling chemical serotonin in the brain.

These included fluoxetine (Prozac) and paroxetine (Seroxat), from the class known as Selective Serotonin Reuptake Inhibitors (SSRIs), alongside another similar drug called venlafaxine (Efexor) - all commonly prescribed in the UK.

The number of prescriptions for anti-depressants hit a record high of more than 31 million in England in 2006 - even though official guidance stresses they should not be a first line treatment for mild depression.

There were 16.2m prescriptions for SSRIs alone.

The researchers found that the drugs did have a positive impact on people with mild depression - but the effect was no bigger than that achieved by giving patients a sugar-coated “dummy” pill.

People with severe symptoms appeared to gain more clear-cut benefit - but this might be more down to the fact that they were less likely to respond to the placebo pill, rather than to respond positively to the drugs.

Lead researcher Professor Irving Kirsch said: “The difference in improvement between patients taking placebos and patients taking anti-depressants is not very great.

“This means that depressed people can improve without chemical treatments.

“Given these results, there seems little reason to prescribe anti-depressant medication to any but the most severely depressed patients, unless alternative treatments have failed to provide a benefit.”

Professor Kirsch said the findings called into question the current system of reporting drug trials.

Reviewing guidance

Dr Tim Kendall, deputy director of the Royal College of Psychiatrists Research Unit, has published research concluding that drug companies tend only to publish research which shows their products in a good light.

These medicines have been licensed by a number of regulatory authorities around the world, who looking at all the evidence, have determined that they do work better than placebo
Dr Richard Tiner
Association of the British Pharmaceutical Industry
 

He said the Hull findings undermined confidence in the ability to draw meaningful conclusions about the merit of drugs based on published data alone.

He called for drug companies to be forced to publish all their data.

The National Institute for Health and Clinical Excellence (NICE) is currently reviewing its guidance on the use of antidepressants.

Marjorie Wallace of Sane commented: “If these results were upheld in further studies, they would be very disturbing.

“The newer anti-depressants were the great hope for the future…. These findings could remove what has been seen as a vital choice for thousands in treating what can be a life-threatening condition.”

Dr Andrew McCulloch, of the Mental Health Foundation, said: “We have become vastly over-reliant on antidepressants when there is a range of alternatives.

“Talking therapies, exercise referral and other treatments are effective for depression.

“It is a problem that needs a variety of approaches matched to the individual patient.”

Dr Richard Tiner, of the Association of the British Pharmaceutical Industry, said there was no doubt that there was a “considerable placebo effect” from anti-depressants when treating people with mild to moderate symptoms.

But he said no medicine would get a licence without demonstrating it was better than a placebo.

Dr Tiner said: “These medicines have been licensed by a number of regulatory authorities around the world, who looking at all the evidence, have determined that they do work better than placebo.”

File this in the “Someday-it-doesn’t-pay-to-get-out-of-bed” department

CNN, 3/21/08:  A woman on a boat died after a spotted eagle ray leaped from the water off the Florida Keys Thursday and struck her, officials said.

art.stingray.wfor.jpg

The dead spotted eagle ray lies on the deck of a boat in Florida.

The force of the blow pushed the woman backward and she died when she hit her head on the boat deck, officials said.

“It’s just as freakish of an accident as I have heard,” said Jorge Pino of the Florida Fish and Wildlife Conservation Commission. “The chances of this occurring are so remote that most of us are completely astonished that this happened.”

The commission identified the woman as Judy Kay Zagorski, 57, of Pigeon, Michigan.

The woman was seated or standing in the front of the boat as her husband piloted the vessel at about 25 mph out of a channel, Pino said. “The ray just actually popped up in front of the vessel,” he said. “The father had not even a second to react. It was too late. It happened instantly and the woman fell backwards and, unfortunately, died as a result of the collision.”

The accident happened off the coast of Marathon, about an hour’s drive south of Miami. The woman, who was with her husband and children, was taken to the Mariner Hospital in Tavernier, where she was pronounced dead.

Pino said he had seen rays leap into the air, but added, “it’s very rare for them to collide with objects.”

The spotted-eagle ray weighed about 75 to 80 pounds and had a six-foot wingspan, Pino said.

Florida Fish and Wildlife said eagle rays “are not an aggressive species, but they do tend to leap from the water.” Spotted eagle rays can have a wingspan of up to 10 feet and can weigh 500 pounds, it said.

Television personality Steve Irwin was killed when a ray’s barb pierced his heart in September 2006.

A month later, an 81-year-old Florida man, James Bertakis, survived after a ray leaped from the water and stung him in the heart, according to the Orlando Sentinel.

He spent five weeks on a ventilator and his recovery took several months, his sons told the Detroit Free Press in his former home state of Michigan.

OMNI Postings of 3/21/08

Postings:  688, 695, 697, 698, 699.

The FDA is thinking about approving Gardasil for women between the ages of 27 and 45.  Currently, it’s approved for girls and women between 9 and 26 years of age.  However, there is no truth to the rumor that an IM injection has been approved for nuns.
http://omniphysicians.com/2008/03/20/gardasil-for-older-women/

Researchers have concluded that straight albuterol works better acutely than beta agonist-steroid drugs such as Advair.
http://omniphysicians.com/2008/03/21/proventil-better-than-advair-symbicort/

Researchers say that asthmatic patients don’t do so well up to 1 month after their ER treatment for an acute exacerbation.  They suggest that these patients should be on inhaled steroids, but many aren’t after discharge.  We prescribe P.O. steroid bursts routinely, but should we be routinely prescribed steroid inhalers?  Would it help overall?  Who knows?  Patients have no money, they have no PCP, they constantly deny the severity of their disease, and they continue to smoke.  There has been 1 study where patients go home with a spirometer and record their numbers on their computer which is linked to an asthma clinic that provides real-time input after the numbers are interpreted.  I know we can do more for these people, but there is no time in most busy ERs.
http://omniphysicians.com/2008/03/21/asthmatics-do-poorly-after-er-treatment/

A study has concluded that spouses enjoying a happy marriage have healthier blood pressures than single people.  Hmm… I wonder….If I were married to Salma Hayek or Halle Berry, I’d have to be on a Nipride drip!
 
http://omniphysicians.com/2008/03/21/blood-pressure-conubial-bliss/

This MMWR report confirms that the incidence of Hep A, B, and C is tracking lower than prior decades.  It’s a nice review of the 3 diseases and their epidemiological findings.
http://omniphysicians.com/2008/03/21/surveillance-for-acute-viral-hepatitis-united-states-2006/

Have a nice weekend and Easter,

Paul R.

Surveillance for Acute Viral Hepatitis — United States, 2006

MMWR March 21, 2008 / 57(SS02);1-24

Abstract

 

Problem/Condition: In the United States, acute viral hepatitis most frequently is caused by infection with three viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV). These unrelated viruses are transmitted through different routes and have different epidemiologic profiles. Safe and effective vaccines have been available for hepatitis B since 1981 and for hepatitis A since 1995. No vaccine exists against hepatitis C.

Reporting Period Covered: Cases in 2006, the most recent year for which data are available, are compared with those from previous years.

Description of System: Cases of acute viral hepatitis are reported voluntarily to CDC by state and territorial epidemiologists via CDC’s National Notifiable Disease Surveillance System (NNDSS). Reports are received electronically via CDC’s National Electronic Telecommunications System for Surveillance (NETSS).

Results: During 1995–2006, hepatitis A incidence declined 90% to the lowest rate ever recorded (1.2 cases per 100,000 population). Declines were greatest among children and in those states where routine vaccination of children was recommended beginning in 1999. An increasing proportion of cases occurred in adults. During 1990–2006, acute hepatitis B incidence declined 81% to the lowest rate ever recorded (1.6 cases per 100,000 population). Declines occurred among all age groups but were greatest among children aged <15 years. Following a peak in the late 1980s, incidence of acute hepatitis C declined through the 1990s; however, since 2003, rates have plateaued, with a slight increas in reported cases in 2006. In 2006, as in previous years, the majority of these cases occurred among adults, and injection-drug use was the most common risk factor.

Interpretation: The results documented in this report suggest that implementation of the 1999 recommendations for routine childhood hepatitis A vaccination in the United States has reduced rates of infection and that universal vaccination of children against hepatitis B has reduced disease incidence substantially among younger age groups. Higher rates of hepatitis B continue among adults, particularly males aged 25–44 years, reflecting the need to vaccinate adults at risk for HBV infection. The decline in hepatitis C incidence that occurred in the 1990s was attributable primarily to a decrease in incidence among injection-drug users. The reasons for this decrease were unknown but likely reflected changes in behavior and practices among injection-drug users.

Public Health Actions: The expansion in 2006 of recommendations for routine hepatitis A vaccination to include all children in the United States aged 12–23 months is expected to reduce hepatitis A rates further. Ongoing hepatitis B vaccination programs ultimately will eliminate domestic HBV transmission, and increased vaccination of adults with risk factors will accelerate progress toward elimination. Prevention of hepatitis C relies on identifying and counseling uninfected persons at risk for hepatitis C (e.g., injection-drug users) regarding ways to protect themselves from infection and on identifying and preventing transmission of HCV in health-care settings.

Introduction

 

Viral hepatitis is caused by infection with any of at least five distinct viruses, of which the three most commonly identified in the United States are hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV). All three of these unrelated viruses can produce an acute illness characterized by nausea, malaise, abdominal pain, and jaundice. HBV and HCV also can produce a chronic infection that is associated with an increased risk for chronic liver disease and hepatocellular carcinoma.

This report describes the burden of acute disease attributed to infection with HAV, HBV, and HCV and describes acute disease trends in recent years. These data can be used to develop and evaluate prevention strategies and identifies persons in need of postexposure prophylaxis. The data on acute illness presented in this report do not include the burden of disease caused by chronic infection with HBV or HCV, both of which remain a substantial public health problem.

Hepatitis A Virus

 

HAV is transmitted through the fecal-oral route, spreading primarily through close personal contact. During 1987–1997, an average of 28,000 cases of hepatitis A occurred per year in the United States (range: 23,112–35,821), making hepatitis A one of the country’s most frequently reported notifiable diseases. However, effective vaccines to prevent HAV infection have been available in the United States since 1995. These vaccines have provided public health authorities with the opportunity to reduce disease incidence in the United States substantially and potentially to eliminate indigenous transmission.

In 1996, CDC’s Advisory Committee on Immunization Practices (ACIP) recommended administration of hepatitis A vaccine for persons at increased risk, including international travelers, men who have sex with men (MSM), injection- and noninjection-drug users, and children living in communities with high rates of disease (1). In 1999, ACIP also recommended that routine vaccination be implemented for children living in 11 states with average hepatitis A rates during 1987–1997 of >20 cases per 100,000 population and also be considered for children in six states with rates of 10–20 cases per 100,000 population (2). In 2005, ACIP expanded these recommendations to include routine vaccination of children in all 50 states (3).

Hepatitis B Virus

 

HBV is transmitted by percutaneous or mucosal exposure to the blood or body fluids of an infected person, most often through injection-drug use [IDU], sexual contact with an infected person, or contact from an infected mother to her infant during delivery. Transmission of HBV also can occur in settings involving nonsexual interpersonal contact for an extended period (e.g., among household contacts of a person with chronic HBV infection). In 1991, a comprehensive strategy was recommended for the elimination of HBV transmission in the United States (4,5). The four elements of this strategy are 1) universal vaccination of infants beginning at birth, 2) prevention of perinatal HBV infection through routine screening of all pregnant women for HBV infection and the provision of immunoprophylaxis to infants born to infected women or to women of unknown infection status, 3) routine vaccination of previously unvaccinated children and adolescents, and 4) vaccination of adults at increased risk for infection (including health care workers, dialysis patients, household contacts and sex partners of persons with chronic HBV infection, recipients of certain blood products, persons with a recent history of multiple sex partners or an STD, MSM, and injection-drug users).

Hepatitis C Virus

 

HCV also is transmitted percutaneously. With an estimated 3.2 million chronically infected persons nationwide, HCV infection is the most common bloodborne infection in the United States (6). No vaccine against HCV infection exists. National recommendations for prevention and control of HCV infection (7), issued in 1998, emphasize primary prevention activities to reduce the risk for HCV transmission. These activities include screening and testing of blood donors, viral inactivation of plasma-derived products, risk-reduction counseling and screening of persons at risk for HCV infection, and routine practice of infection control in health-care settings.

Methods

Conditions for Which Surveillance is Conducted

 

National surveillance is conducted for acute hepatitis A, B, and C. The case definitions for these conditions are approved by the Council of State and Territorial Epidemiologists (CSTE) and are provided in this report.

Data Sources

 

Cases of acute viral hepatitis are reported to CDC weekly by state and territorial health departments to CDC’s National Notifiable Diseases Surveillance System (NNDSS). Since January 1, 2002, all reports have been submitted electronically to CDC via the National Electronic Telecommunications System for Surveillance (NETSS).

States’ participation in reporting nationally notifiable diseases, including acute viral hepatitis, to CDC is voluntary. All states collect and report basic information (e.g., event date, source of report, and demographic characteristics) regarding cases of acute viral hepatitis that are identified in their states. States also are asked to report additional information (e.g., laboratory test results, clinical information, and exposure history) regarding investigated cases, but completeness of reporting of these additional data varies. As in previous years, approximately 40% of case reports received by CDC include any of these additional data. Information regarding state-specific reporting profiles is provided in this report (Table 1).

Case Definitions for Acute Viral Hepatitis

 

In 2006, cases were required to meet the clinical definition for acute hepatitis and virus-specific laboratory criteria for diagnosis specified in the following CSTE-approved case definitions.

Clinical Case Definition

Acute hepatitis was defined as acute illness with 1) discrete onset of symptoms (e.g., nausea, anorexia, fever, malaise, or abdominal pain) and 2) jaundice or elevated serum aminotransferase levels.

Laboratory Criteria for Diagnosis of Hepatitis

Because the clinical characteristics are the same for all types of acute viral hepatitis, laboratory testing is needed to identify the specific viral cause of illness. The laboratory criteria for confirming each type of acute viral hepatitis are as follows:

  • Acute hepatitis A
    — Immunoglobulin M (IgM) antibody to hepatitis A virus (anti-HAV) positive
  • Acute hepatitis B
    — IgM antibody to hepatitis B core antigen (anti-HBc) positive or hepatitis B surface antigen (HBsAg) positive and
    — IgM anti-HAV negative (if performed)
  • Acute hepatitis C
    — Serum alanine aminotransferase levels higher than seven times the upper limit of normal, and
    — IgM anti-HAV negative, and
    — IgM anti-HBc negative, or if not performed, HBsAg negative, and
    — One of the following

    • Antibody to hepatitis C virus (anti-HCV) screening-test-positive, verified by an additional more specific assay (e.g., RIBA for anti-HCV or nucleic acid testing for HCV RNA)
                                                                                                                            OR
    • Anti-HCV screening-test positive with a signal to cut-off ratio predictive of a true positive as determined for the particular assay (e.g., >3.8 for the enzyme immunoassays).

 

Case Classification

For this analysis, a confirmed case was one that met the clinical case definition and was laboratory-confirmed. For hepatitis A, a case also was considered confirmed that met the clinical case definition and was diagnosed in a person who had an epidemiologic link to a person who had laboratory-confirmed hepatitis A (i.e., household or sexual contact with an infected person during the 15–50 days before the onset of symptoms).

Analyses

 

Incidence Calculations

For this analysis, crude rates per 100,000 population were calculated using Bureau of the Census estimates of the U.S. resident population in 2006. The following U.S. geographic regions were used: Midwest, Northeast, South, and West.*

Frequency Analysis

For this analysis, the percentage of persons who reported a specific risk factor was determined by using the number of persons who reported any information, positive or negative, regarding that exposure as the denominator. Depending on the type of hepatitis, the percentage of case reports that included any risk factor information ranged from 30%–40%. Multiple risk factors may be reported for a single person. Consequently, the percentages of persons with specific risk factors might total >100%.

Results

Acute Viral Hepatitis A

 

Overall Incidence

Historically, acute hepatitis A rates have varied cyclically, with nationwide increases every 10–15 years. The national rate of hepatitis A has declined steadily since the last peak in 1995. In 2006, a total of 3,579 acute symptomatic cases of hepatitis A were reported, the national incidence (1.2 per 100,000 population) was the lowest ever recorded (Figure 1; Tables 2 and 3). After asymptomatic infection and underreporting were taken into account, an estimated 32,000 new infections occurred in 2006 (8).

Rates by Region

In addition to temporal variation, historically, hepatitis A rates have varied geographically, with higher rates reported in the western region of the United States. However, incidence in the West has declined substantially, most notably after issuance in 1999 of recommendations for routine childhood vaccination in states with consistently elevated rates of hepatitis A (2). In 2006, rates in the West were approximately equal to those in other regions of the United States (Figures 2 and 3).

Rates by Age

Incidence of hepatitis A varies by age. Since the last nationwide increase in 1995, rates have declined among all age groups, but the greatest decreases have occurred among children. Historically, the highest rates were observed among children and young adults; the lowest rates were among persons aged >40 years. However, since 1997, rates among children have declined more rapidly than rates among adults, and, in 2006, rates were similar across all age groups, ranging from 0.7 cases per 100,000 population among children aged <5 years to 1.4 cases per 100,000 population among persons aged 5--14 years (Figure 4). Since 2000, the lowest rates have occurred among children aged <5 years. However, asymptomatic infection is common among young children, and symptomatic cases in children aged <5 years represent only a limited proportion of infections that occur in this age group.

Rates by Sex

Rates of hepatitis A consistently have been higher among males than among females, and, during the late 1990s through 2001, the difference in the sex-specific rates increased until nearly two male cases were observed for every female case. However, beginning in 2001, rates declined more among males than among females, and, since 2003, the ratio of the number of male cases to female cases has ranged from 1.2 to 1.3. In 2006, overall incidence among males was 1.3 cases per 100,000 population compared with 1.1 cases per 100,000 population among females. The difference in hepatitis A rates by sex was highest among persons aged 30–49 years (Figures 5 and 6).

Rates by Race and Ethnicity

Hepatitis A rates have differed historically by race; the highest rates occurred among American Indian/Alaska Natives (AI/ANs), and the lowest rates have occurred among Asians/Pacific Islanders (APIs). However, rates among AI/ANs, which were >60 cases per 100,000 population before 1995, have decreased dramatically, and, since 2003, have been lower than those for other races. In 2006, the rate for AI/ANs was 0.5 cases per 100,000 population. Hepatitis A rates also have differed by ethnicity; rates among Hispanics have consistently been higher compared with non-Hispanics. Rates among Hispanics have decreased since 1997 but remain higher than those for non-Hispanics (Figure 7).

Reported Risk Factors

In 2006, among cases for which information regarding exposures during the incubation period was collected, the most frequently identified risk factor for hepatitis A was international travel (reported by 15% of case patients overall). As in previous years, the majority of travel-related cases were associated with travel to Mexico and Central/South America (72%). As HAV transmission in the United States has decreased, cases among travelers to countries in which hepatitis is endemic have accounted for an increased proportion of all cases.

Sexual and household contact with another person with hepatitis A has been among the most frequently identified risks; in 2006, such contact was reported for 10% of cases. During 2004–2006, the proportion of cases reported among MSM increased from 3% to 9%, and the proportion of cases in persons reporting IDU declined from 13% to 2% (Table 4; Figure 8).

Clinical Characteristics

In 2006, the clinical characteristics of reported hepatitis A cases were similar to previous years; 73% of infected persons had jaundice, 33% were hospitalized for hepatitis A, and 0.3% died from hepatitis A. The proportion of persons hospitalized increased with age, from 22% among children aged <5 years to 52% among persons aged >60 years (Table 5).

Acute Hepatitis B

 

Overall Incidence

In 2006, a total of 4,713 acute, symptomatic cases of hepatitis B were reported nationwide. The overall incidence (1.6 cases per 100,000 population) was the lowest ever recorded and represents a decline of 81% since 1990 (Tables 2 and 6; Figure 9). After asymptomatic infection and underreporting were taken into account, an estimated 46,000 new infections occurred in 2006 (8).

Rates by Region

Hepatitis B rates continued to decline in all U.S. regions (Figures 10 and 11). Since 2001, the highest rates have occurred in the South.

Rates by Age

Hepatitis B rates varied by age, with the highest rate in 2006 (3.1 cases per 100,000 population) reported among persons aged 25–44 years and the lowest (0.02 cases per 100,000 population) reported among persons aged <15 years. Rates declined in all age groups. Since 1990, the greatest percentage declines have occurred among persons aged <15 years (98%) and those aged 15--24 years (93%). Although not as large as the declines in the younger age groups, substantial decreases also have occurred among older persons; the rates observed for persons aged 25--44 years and >45 years have decreased 78% and 61%, respectively (Figure 12).

Rates by Sex

As in previous years, in 2006, the rate of acute hepatitis B for males (2.0 cases per 100,000 population) was higher than that for females (1.1 case per 100,000 population). Since 1990, male-to-female ratio of cases has increased gradually. In 2006, the rate for males was approximately 1.8 times higher than that for females (Figure 13). This difference in hepatitis B rates by sex occurred primarily among persons aged >19 years and increased with age (Figure 14).

Rates by Race and Ethnicity

In 2006, rates of hepatitis B continued to decline among all racial/ethnic populations; however, recent declines have been less than earlier in the decade (Figure 15). Rates of hepatitis B are similar across racial/ethnic populations, except for non-Hispanic blacks; the rate for this population (2.3 cases per 100,000 population) was higher than for other populations. The downward trend in the rate among APIs continues, and, in 2006, the rate for this population (1.2 cases per 100,000 population) was similar to Hispanics and to non-Hispanic whites (1.1 case per 100,000 population, for both populations).

Reported Risk Factors for Infection

Of persons for whom information regarding exposures during the incubation period was available, approximately one third reported at least one sexual risk factor (i.e., 8%, sexual contact with a person known to have hepatitis B; 34%, multiple sexual partners; and 15%, MSM). IDU was reported for 16% of persons. Since 2001, the proportion of persons who reported either a sexual risk or IDU has increased gradually as the number of cases attributable to other sources of transmission (e.g., blood transfusions and dialysis) has declined. The proportion of persons who reported receiving hemodialysis or a blood transfusion (both of which historically were major sources of infection) or having had occupational exposure to blood was low (0.2%, 0.6%, and 0.5%, respectively) (Table 7; Figure 16).

Clinical Characteristics

In 2006, of persons reported with hepatitis B, 77% had jaundice, 40% were hospitalized, and 0.8% died. The proportion of persons hospitalized for hepatitis B increased with age, from 12% among children aged <15 years to 51% among persons aged >60 years (Table 8).

Acute Hepatitis C

 

Overall Incidence

During 2005–2006, the number of confirmed cases of acute hepatitis C reported increased 19%, from 671 to 802. The overall national rate for 2006 was 0.3 cases per 100,000 population. After asymptomatic infection and underreporting were taken into account, approximately 19,000 new HCV infections occurred in 2006 (8) (Tables 2 and 9; Figure 17).

Rates by Age

Since the mid-1990s, hepatitis C rates have declined in all age groups. However, rates appear to have reached a plateau since 2003. The greatest decline has occurred among persons aged 25–39 years, the age group that historically has had the highest rates of disease. Among this age group, incidence has declined 58% since 2000. In 2006, rates increased slightly among persons aged 25–39 years (0.47 per 100,000 population) and those aged 15–24 years (0.37 per 100,000 population). Few cases are reported among persons aged <15 years (Figure 18).

Rates by Sex

In 2006, as in previous years, the rate of hepatitis C was higher for males (0.29 cases per 100,000 population) than for females (0.25 cases per 100,000 population). However, this differential in rates has declined over the decade. In 2006, the male-to-female ratio was the smallest since reporting began (Figures 19 and 20).

Rates by Race and Ethnicity

Since 1995, the incidence of hepatitis C has declined in all racial populations. In 2006, rates were similar across racial/ethnic populations and ranged from 0.62 cases per 100,000 population among AI/ANs to 0.07 cases per 100,000 population among APIs (Figure 21).

Reported Risk Factors for Infection

Of the cases reported in 2006 for which information concerning exposures during the incubation period was available, the most common risk factor identified was IDU (54%). During the previous decade, IDU was reported for an average of 42% of persons (range: 31%–54%). In 2006, 36% reported having had multiple sexual partners during the incubation period, and 10% reported sexual contact with another known HCV-infected person. Having had surgery was reported for 16% of persons with hepatitis C. A total of 1.5% reported occupational exposure to blood (Table 10; Figure 22).

Clinical Characteristics

In 2006, of persons reported with hepatitis C, 66% had jaundice, 41% were hospitalized, and 0.2% died (Table 11).

Discussion

 

National surveillance data for acute viral hepatitis provides the information needed for developing prevention strategies and monitoring their effectiveness. Since national surveillance for acute viral hepatitis in the United States began in 1966, major changes in the epidemiology of these diseases have occurred. During 1995–2006, rates for all three types of acute viral hepatitis declined dramatically. These declines partially resulted from implementation of comprehensive prevention strategies for each disease, including the introduction of effective vaccines against hepatitis A and hepatitis B.

Hepatitis A

 

Hepatitis A rates have varied cyclically, with peaks occurring approximately every 10–15 years; the last peak in morbidity occurred in 1995. The incidence of hepatitis A began to decline after the introduction of licensed hepatitis A vaccines in the United States in 1995 and the issuance in 1996 of the first public health recommendations for the use of vaccine to prevent transmission of HAV (1). The greatest declines have occurred since 1999, when recommendations were made for routine vaccination of children living in states with consistently elevated rates of hepatitis A. These recommendations called for 1) routine vaccination of children living in states and communities where the average hepatitis A rate during the baseline period (1987–1997) was >20 cases per 100,000 population (twice the national average) and for 2) consideration of vaccination of children in those states and communities where the average rate during the baseline period was at least 10 cases per 100,000 but not as high as 20 cases per 100,000 population (2).

After implementation of the recommended vaccination strategy, major changes occurred in the geographic distribution of hepatitis A. Relative to their prevaccine-era rates, a substantially greater decline occurred for the 17 western and midwestern states that were included in the 1999 recommendation than for the remainder of the country (9). As a result of this decline, hepatitis A rates now are similar across all regions.

After the implementation of routine childhood vaccination, changes in the age distribution also occurred. During the prevaccine era, the reported incidence of hepatitis A was highest among children aged 5–14 years; approximately one third of reported cases occurred among children aged <15 years. Since implementation of routine childhood vaccination, incidence has declined more sharply among the age groups (i.e., 2--18 years) covered by the recommendations than among older age groups. As a result, rates now are similar among all age groups (9). In 2006, the highest rates of disease occurred among adults, particularly among males aged 20–44 years. The low and relatively stable rates among persons aged >40 years reflect the higher proportion of persons in this age group who had immunity as a result of previous infection. Data from the Third National Health and Nutrition Examination Survey (NHANES III) conducted during 1988–1994 indicated that approximately 30% of the U.S. population had serologic evidence of immunity to HAV, reaching a high of 75% among persons aged >70 years (10).

Disparities in rates among racial/ethnic populations also decreased after the introduction of hepatitis A vaccine. In particular, rates among AI/ANs were five times those of other racial/ethnic population during the prevaccine era. Widespread use of hepatitis A vaccine in Native American communities began in 1996 (11), and rates in this population now are lower than those of other racial/ethnic populations. Hispanics also historically have had elevated hepatitis A rates, and although incidence among Hispanics declined >85% during 1996–2006, the 2006 rate for Hispanics (2.3 cases per 100,000 population) is two to four times higher than the rate for non-Hispanics.

The observed declines in the incidence of hepatitis A were accompanied by shifts in epidemiologic profile of this disease. The substantial communitywide outbreaks that occurred as a result of person-to-person contact in households and extended family settings have become increasingly rare. The disappearance of these outbreaks can be attributed to declining rates of infection among children who, because they frequently have asymptomatic infection, have often played a key role is sustaining HAV transmission. As this type of transmission has decreased, the proportion of cases among persons in high-risk populations (particularly international travelers, injection-drug users, and MSM) has increased. Although the absolute number of cases associated with international travel has remained nearly unchanged, the proportion of cases attributable to this exposure has increased, accounting for 15% of all cases in 2006. Approximately 70% of all travel-related cases were associated with travel to Mexico and to Central or South America. Outbreaks of hepatitis A among injection-drug users and MSM also have continued to occur although hepatitis A vaccine has been recommended for these populations since 1996.

In 2005, the licensing of hepatitis A vaccines was revised to allow vaccination of children aged 12–23 months, which has made feasible the incorporation of hepatitis A vaccine into the schedule of other routinely recommended childhood vaccines. In 2006, ACIP recommended that all children in the United States aged 12–23 months receive hepatitis A vaccine (3). Nationwide hepatitis A vaccination of children is likely to result in further narrowing of current demographic disparities and in lower overall rates of infection. The 2006 recommendations provide the foundation for eventual consideration of elimination of indigenous HAV transmission in the United States. Ongoing surveillance for acute hepatitis A provides the data needed to measure the progress toward that goal.

Hepatitis B

 

The decline in hepatitis B incidence began in the mid-1980s and has coincided with the stepwise implementation of the national vaccination strategy to eliminate HBV transmission. The 2006 rate of 1.6 cases per 100,000 population was the lowest recorded since surveillance began in 1966 and represents an estimated decline of >80% since the national strategy was implemented in 1991.

The greatest declines have occurred among the cohort of children to whom the recommendations for routine infant and adolescent vaccination have applied. During 1990–2006, incidence among children aged <15 years declined 98%, from 1.2 cases per 100,000 population to 0.02 cases per 100,000 population. This decline correlates with high vaccine coverage rates among young children, with the most recent data indicating that coverage among children aged 19--35 months is >93% (12).

Although incidence also has declined among persons aged 25–44 years, rates in this age group, particularly among males, still remained substantially higher than in any other age group. A high proportion of these cases occurred among persons with risk factors for HBV infection (e.g., injection-drug users, MSM, and persons with multiple sex partners). The male-to-female ratio has increased gradually; in 2006, approximately 1.8 male cases were reported for every female case. Few cases now occur in certain populations that previously were considered to be at high risk (e.g., dialysis patients and health-care workers) as a result of continued improvements in infection control and ongoing hepatitis B vaccination in these groups. A 2003 survey indicated that approximately 75% of health-care workers have been vaccinated against hepatitis B (13). In 2002, coverage among dialysis patients was 56% (14). Transmission associated with transfusions is rare as a result of required screening of blood products. In contrast, the continued occurrence of cases among injection-drug users and persons with sexual risk factors indicates a need to strengthen efforts to reach these populations with vaccine. In 2007, in collaboration with state and local health agencies, CDC launched the Adult Hepatitis B Vaccination Initiative to provide approximately $20 million of funding for grantees to purchase hepatitis B vaccine and begin or expand delivery of viral hepatitis prevention services in public health settings serving adults at risk for viral hepatitis.

Since 1990, progress has been made in reducing racial/ethnic disparities in hepatitis B rates. Before 1990, APIs had disproportionately higher rates of hepatitis B. The decrease in disparity between APIs and other racial/ethnic populations was consistent with observed declines in the seroprevalence of HBV infection among high-risk Asian children after the successful implementation of routine hepatitis B vaccination (15,16). Although rates among non-Hispanic blacks have declined, they remain more than twofold higher than those among other racial/ethnic populations. Although progress has been made in reducing disparities in incidence of new infection, the impact of these disparities in the past are reflected in current prevalence patterns, with higher prevalences of chronic HBV infection among APIs and non-Hispanic blacks than among other populations.

Health-care–related transmission of hepatitis B is documented infrequently in the United States but should be considered when cases of acute viral hepatitis are identified in persons without traditional risk factors. The declining incidence of hepatitis B has been associated with increasing recognition of sporadic cases associated with medical care (17,18). State and local health authorities should consider strategies to improve detection of health-care–associated cases, such as targeting intensive follow-up for persons who typically are at low risk for infection (e.g., persons aged >60 years).

Surveillance data for acute hepatitis B are needed for measuring the effectiveness of the HBV-elimination strategy. However, to describe completely the burden of HBV infection in the United States and to better assess the effectiveness of certain components of the prevention strategy, other types of surveillance data also are needed. Data from a national seroprevalence survey indicate that approximately 1.3 million persons in the United States are living with chronic HBV infection (19). As incidence of acute hepatitis B continues to decline, seroprevalence surveys are needed to validate incidence data and describe the burden of chronic HBV infection.

Hepatitis C

 

After peaking in the late 1980s, the incidence of hepatitis C declined steadily through the 1990s. However, since 2003, hepatitis C rates have plateaued, with IDU remaining the most commonly identified risk factor for infection. Transmission of HCV associated with transfusion, an important risk for infection in previous years, was rare as a result of required blood screening. The investigation of persons without typical risk factors will help to ensure the detection of transmission associated with medical care and other uncommon sources of infection.

Since 1992, the greatest declines in incidence of acute hepatitis C have occurred among persons aged 25–39 years, the age group that historically had the highest rates of infection. In 2006, cases among children continued to be rare. Progress has been made in reducing disparities in racial/ethnic-specific rates; in 2006, the incidence of acute hepatitis C was similar across all racial/ethnic populations. However, previous racial/ethnic disparities in incidence were demonstrated by disparities in prevalence, with a higher prevalence of chronic infection among non-Hispanic blacks than among other racial/ethnic populations.

Although the number of new cases of acute hepatitis C has declined, a substantial burden of disease as a result of chronic infection still persisted in 2006. Approximately 3.2 million persons in the United States were chronically infected with HCV; the peak prevalence occurred among persons aged 40–49 years, the majority of whom likely became infected in the 1970s and 1980s, when incidence was highest (4). Data on both the incidence of acute disease and the prevalence of chronic infection are needed to assess the burden of disease attributable to HCV infection in the United States comprehensively. However, surveillance for acute hepatitis C remains critical as the best means to assess the impact of primary prevention strategies, determine where transmission continues to occur, and identify and control outbreaks.

Limitations

 

The analyses summarized in this report were performed on the basis of cases of symptomatic, serologically confirmed, acute viral hepatitis reported to NNDSS. NNDSS is a passive surveillance system and subject to at least two limitations. First, the cases reported represent only a portion of all infections. Surveillance for acute disease is not intended to identify asymptomatic infections, and certain persons with symptomatic illness also are not identified and reported. Studies have estimated that for each hepatitis case reported to NNDSS, two to five cases that would meet the case definition are not reported (20,21). Second, completeness of case reports also can vary. However, available evidence suggests that no systematic changes have occurred in reporting patterns since 1990 (CDC, unpublished data, 2007). The national trends in this report also are reflected in CDC’s Sentinel Counties Study of Acute Viral Hepatitis, in which the accuracy and completeness of reporting were assessed and known to be high (22). Rates based on NNDSS data represent a lower estimate of the incidence of acute viral hepatitis in the United States because not all cases of acute hepatitis are reported. However, because the proportion of cases not reported has not changed systematically over time, these estimates accurately reflect changing trends in these diseases in the United States.

Conclusion

 

Surveillance for acute viral hepatitis accomplishes multiple key public health objectives. Surveillance detects outbreaks, identifies persons in need of postexposure prophylaxis, and provides information on trends in the incidence and risks for recent infection that is needed to develop and evaluate prevention strategies. The minimum data required to conduct surveillance for acute viral hepatitis are laboratory confirmation of cases to distinguish the types of acute hepatitis and clinical information to verify the case definition. The collection of risk data provides valuable information for identifying modes of hepatitis transmission and for implementing and evaluating prevention strategies.

With continuing declines in the incidence of all types of acute viral hepatitis, surveillance efforts should be enhanced to ensure complete and accurate reporting of all cases so that the impact of strategies for preventing or eliminating transmission of these diseases can be monitored and evaluated. In addition, effective and feasible systems for conducting surveillance for chronic hepatitis virus infections are needed to characterize the burden of chronic disease that remains in the United States as a result of these infections.

Acknowledgment

 

Data for this report were provided by State and Territorial Health Departments.

References

 

  1. CDC. Prevention of hepatitis A through active or passive immunization. MMWR 1996;45(No. RR-15).
  2. CDC. Prevention of hepatitis A through active or passive immunization. MMWR 1999; 48(No. RR-12).
  3. CDC. Prevention of Hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2006;55(No. RR-7).
  4. CDC. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States. Part 1: immunization of infants, children, and adolescents. MMWR 2005;54 (No. RR-16).
  5. CDC. A comprehensive immunization strategy to eliminate transmission of hepatitis B virus infection in the United States—recommendations of the Advisory Committee on Immunization Practices (ACIP). Part 2: immunization of adults. MMWR 2006;55(No. RR-16).
  6. Armstrong GL, Wasley AM, Simard EP, McQuillan GM, Kuhnert WL, Alter MJ. The prevalence of hepatitis C virus infection in the United States, 1999 through 2002. Ann Intern Med 2006; 144:705–14.
  7. CDC. Recommendations for prevention and control of hepatitis C virus (HCV) infection and HCV-related chronic disease. MMWR 1998;47(No. RR-19).
  8. CDC. Estimates of disease burden from viral hepatitis. Atlanta, GA: US Department of Health and Human Services, CDC; 2006. Available at http://www.cdc.gov/ncidod/diseases/hepatitis/resource/PDFs/disease_burden.pdf.
  9. Wasley A, Samandari T, Bell BP. Incidence of hepatitis A in the United States in the era of vaccination. JAMA 2005;294:194–201.
  10. Bell BP, Kruszon-Moran D, Shapiro CN, et al. Hepatitis A virus infection in the United States: serologic results from the Third National Health and Nutrition Examination Survey. Vaccine 2005;23:5798–806.
  11. Bialek SR, Thoroughman DA, Hu D, et al. Hepatitis A incidence and hepatitis A vaccination among American Indians and Alaska Natives, 1990–2001. Am J Public Health 2004;94:996–1001.
  12. CDC. National, state, and urban area vaccination coverage among children aged 19–35 months—United States, 2005. MMWR 2006;55:988–93.
  13. Simard E, Miller JT, George PA, et al. Hepatitis B vaccination coverage levels among health care workers in the United States, 2002–2003. Infect Control Hosp Epidemiol 2007;28:783–90..
  14. Finelli L, Miller JT, Tokars JI, Alter MJ, Arduino MJ. National surveillance of dialysis-associated diseases in the United States, 2002. Sem Dialysis 2005;18: 52– 61.
  15. Perz JF, Elm JL, Fiore AE, Huggler JI, Kuhnert WL, Effler PV. Near elimination of hepatitis B virus infections among Hawaii elementary school children following universal infant hepatitis B vaccination. Pediatrics 2006;118 1403–8.
  16. Fiore A, Neeman R, Lee S, et al. Seroprevalence of hepatitis B virus (HBV) infection among Asian immigrants and their US-born children in Georgia [Abstract 586]. In: Abstracts of the Infectious Diseases Society of America 41st Annual Meeting, San Diego, California, October 9–12, 2003. Alexandria, VA: Infectious Diseases Society of America; 2003.
  17. Williams IT, Perz JF, Bell BP. Viral hepatitis transmission in ambulatory health care settings. Clin Infect Dis 2004;38:1592–8.
  18. CDC. Transmission of hepatitis B and C viruses in outpatient settings—New York, Oklahoma, and Nebraska, 2000–2002. MMWR 2003;52:901–6.
  19. McQuillan GM, Coleman PJ, Kruszon-Moran D et al. Prevalence of hepatitis B virus infection in the United States: the National Health and Nutrition Examination Surveys, 1976 through 1994. Am J Pub Health 1999;89:14–8.
  20. Doyle TJ, Glynn MK, Groseclose SL. Completeness of notifiable infectious disease reporting in the United States: an analytical literature review. Am J Epidemiol 2002;155:866–74.
  21. Armstrong GL, Bell BP. Hepatitis A virus infections in the United States: model-based estimates and implications for childhood immunization. Pediatrics 2002;109:839-45.
  22. Alter MJ, Mares A, Hadler SC, Maynard JE. The effect of underreporting on the apparent incidence and epidemiology of acute viral hepatitis. Am J Epidemiol 1987;125:133–9.

1

1

1

1

1

 

Proventil better than Advair & Symbicort

MedPage Today, 3/21/08:  (3/20, Gever) reported that a team at Central Texas Health Research suggests that Proventil (albuterol) “brought faster increases in asthma patients’ lung function than did two corticosteroid-beta agonist combination agents,” according to findings presented at the American Academy of Allergy, Asthma, and Immunology meeting. Approximately “51 percent of patients receiving albuterol showed at least 15 percent improvement in” bronchodilation “within 15 minutes of dosing, versus 40 percent of patients taking” Symbicort (budesonide-formoterol), and “18 percent of patients treated with” Advair (fluticasone-salmeterol). The team reached the aforementioned conclusions after a 109 patients were instructed to inhale “two 80-mcg puffs of budesonide alone twice daily” for two weeks. 

Then they “took each of the study medications on separate occasions in random order: two puffs of placebo, two puffs of 80/4.5 mcg of budesonide-formoterol, one puff of 250/50 mcg of fluticasone-salmeterol, and two puffs of 90 mcg of albuterol.”  The research team also found that “[b]udesonide-formoterol” significantly increased bronchodilation “within three minutes to a greater extent than did fluticasone-salmeterol.”

Asthmatics do poorly after ER treatment

Intro:  Not surprising at all.  Patients deny the seriousness of their problem.  They don’t have adequate follow-up.  They can’t afford their meds.  Studies have shown how technology, namely computers, can’t assist with monitoring these patients at home.

Reuters, 3/21/08:  Adults treated in the emergency room for severe asthma often continue to have poorly controlled symptoms afterward, new research suggests.

In a study of 225 adults who visited an ER for an asthma flare-up, researchers found that most patients had suffered persistent symptoms during the previous month, and only about half of them were taking inhaled steroids to help prevent asthma attacks.

One month after the ER visit, many still had poorly controlled symptoms, the researchers report in the Annals of Allergy, Asthma and Immunology.

The findings suggest that emergency care for asthma can be better, and that the “bridge” between the ER and the doctor’s office can be stronger, write Dr. Richard O. Lenhardt, of Rush University Medical Center in Chicago, and his colleagues.

In the ER, asthma exacerbations are usually treated with oral corticosteroid medication, Lenhardt explained, but this is a short- term solution. If patients do not get their asthma under better control, they are at risk of seeing their symptoms worsen again once they stop taking the oral drugs, he told Reuters Health.

The problem is that many people do not go to see their primary care doctor after their ER visit, according to Lenhardt. He said that emergency physicians may be able to do more to encourage patients to see their regular doctor as soon as possible.

The study involved 225 adults who had an asthma exacerbation treated at one of six Illinois ERs over six months. The researchers questioned them about their symptoms and medication use in the previous month, then called them one month after the ER visit to see how they were faring.

Nearly 86 percent of patients said they’d had persistent asthma symptoms in the month before the ER visit. Of this group, only 54 percent were using inhaled corticosteroids, despite the fact that national guidelines recommend that this be the primary therapy for such patients.

Even fewer — about one-quarter — were using inhaled corticosteroids daily to prevent symptoms, the study found.

One month after their ER visit, more patients were on inhaled corticosteroids, with three-quarters saying they used the medications and 59 percent reporting daily use. However, many patients still had problems with controlling their symptoms.

Just as many reported persistent symptoms after their ER visit as before, the researchers found. Furthermore, on a standard measure of quality of life, the average score for the study group was lower than what has been found for adults with asthma in general.

For adults who’ve had to get emergency asthma care, the bottom line is that they should talk to their doctor about how to get a better handle on the disease.

“It might mean they need more medication, better avoidance of allergens, better use of the current medications, and other reasons that could be sorted out by their primary care physician,” Lenhardt said.

SOURCE: Annals of Allergy, Asthma and Immunology, March 2008.

FDA approves Artiss

HealthDay News, 3/21/08:  Artiss, a fibrin sealant used to attach skin grafts in burn patients, has been approved by the U.S. Food and Drug Administration.Fibrin sealants are medical adhesives that contain two proteins — fibrinogen and thrombin — that are critical to blood clotting. Artiss contains lower amounts of thrombin than similar adhesives, giving surgeons more time to align grafts before they begin adhering to the skin.

The blood proteins are obtained from human plasma, which is purified and treated to thwart viruses before use.

Artiss was clinically tested on 138 patients, each of whom had two wound sites. One wound on each patient was grafted using Artiss, the other with surgical staples. The trials showed that Artiss performed as well as staples, the FDA said.

Side effects of Artiss included bleeding and fluid collection in the tissues, which are common reactions after skin grafts, the agency said.

Artiss is manufactured by Baxter International.

Blood Pressure & Conubial Bliss

 

Study suggests happily married individuals may have lower blood pressure than single, unhappily married people.

The UPI (3/21) reports that while individuals “in happy marriages have lower blood pressure than single people,…unhappily married adults have higher blood pressure,” according to a study published in the Apr. issue of the Annals of Behavioral Medicine. Julianne Holt-Lunstad, Ph.D., an assistant psychology professor at Brigham Young University, and colleagues, “had 204 married and 99 single adults wear portable blood pressure monitors for 24 hours.”

        The participants “wore devices that recorded their blood pressure at random times over 24 hours,” the AP (3/21, Ritter) adds. After analyzing the data, the researchers “found that the more marital satisfaction and adjustment spouses reported, the lower their average blood pressure was over the 24 hours, and during the daytime.” But, “spouses who scored low in marital satisfaction had higher average blood pressure than single people did.” Moreover, in “the daytime, their average was about five points higher.”

Importance of wife in hubby’s cancer

 

Study suggests wife’s frame of mind influences husband’s physical health among couples dealing with cancer.

HealthDay (3/20, Mozes) reported that “[f]or couples coping with cancer, the physical health of the husband — as either patient or caregiver — appears particularly influenced by the wife’s frame of mind,” according to a study due to be published in the Annals of Behavioral Medicine. Youngmee Kim, Ph.D., director of the American Cancer Society’s Family Studies Research, surveyed “the quality of life and psychological distress experienced by 168 married, patient-caregiver pairs — half coping with breast cancer, half coping with prostate cancer.” Kim found that “although all the caregivers and patients appeared to both affect and be affected by each other’s state of mind, gender drove some differences in the pair’s dynamic — with men generally more vulnerable.” Moreover, the “greater the psychological distress among wives suffering from breast cancer, the poorer the physical health of their caretaking husbands — regardless of the husband’s own quality of life.” The author “suggested that the greater sensitivity observed among men could be a function not just of typical gender roles, but also of related communication patterns.”

More parents skeptical of vaccinations for kids

NY Times, 3/21/08:  In a highly unusual outbreak of measles here last month, 12 children fell ill; nine of them had not been inoculated against the virus because their parents objected, and the other three were too young to receive vaccines.The parents who objected to their children being inoculated are among a small but growing number of vaccine skeptics in California and other states who take advantage of exemptions to laws requiring vaccinations for school-age children.

The exemptions have been growing since the early 1990s at a rate that many epidemiologists, public health officials and physicians find disturbing.

Children who are not vaccinated are unnecessarily susceptible to serious illnesses, they say, but also present a danger to children who have had their shots — the measles vaccine, for instance, is only 95 percent effective — and to those children too young to receive certain vaccines.

Measles, almost wholly eradicated in the United States through vaccines, can cause pneumonia and brain swelling, which in rare cases can lead to death. The measles outbreak here alarmed public health officials, sickened babies and sent one child to the hospital.

Every state allows medical exemptions, and most permit exemptions based on religious practices. But an increasing number of the vaccine skeptics belong to a different group — those who object to the inoculations because of their personal beliefs, often related to an unproven notion that vaccines are linked to autism and other disorders.

Twenty states, including California, Ohio and Texas, allow some kind of personal exemption, according to a tally by the Johns Hopkins University.

“I refuse to sacrifice my children for the greater good,” said Sybil Carlson, whose 6-year-old son goes to school with several of the children hit by the measles outbreak here. The boy is immunized against some diseases but not measles, Ms. Carlson said, while his 3-year-old brother has had just one shot, protecting him against meningitis.

“When I began to read about vaccines and how they work,” she said, “I saw medical studies, not given to use by the mainstream media, connecting them with neurological disorders, asthma and immunology.”

Ms. Carlson said she understood what was at stake. “I cannot deny that my child can put someone else at risk,” she said.

In 1991, less than 1 percent of children in the states with personal-belief exemptions went without vaccines based on the exemption; by 2004, the most recent year for which data are available, the percentage had increased to 2.54 percent, said Saad B. Omer, an assistant scientist at the Johns Hopkins Bloomberg School of Public Health.

While nationwide over 90 percent of children old enough to receive vaccines get them, the number of exemptions worries many health officials and experts. They say that vaccines have saved countless lives, and that personal-belief exemptions are potentially dangerous and bad public policy because they are not based on sound science.

“If you have clusters of exemptions, you increase the risk of exposing everyone in the community,” said Dr. Omer, who has extensively studied disease outbreaks and vaccines.

It is the absence, or close to it, of some illnesses in the United States that keep some parents from opting for the shots. Worldwide, 242,000 children a year die from measles, but it used to be near one million. The deaths have dropped because of vaccination, a 68 percent decrease from 2000 to 2006.

“The very success of immunizations has turned out to be an Achilles’ heel,” said Dr. Mark Sawyer, a pediatrician and infectious disease specialist at Rady Children’s Hospital in San Diego. “Most of these parents have never seen measles, and don’t realize it could be a bad disease so they turn their concerns to unfounded risks. They do not perceive risk of the disease but perceive risk of the vaccine.”

Dr. Sawyer and the vast majority of pediatricians believe strongly that vaccinations are the cornerstone of sound public health. Many doctors view the so-called exempters as parasites, of a sort, benefiting from the otherwise inoculated majority.

Most children get immunized to measles from a combined measles, mumps and rubella vaccine, a live virus.

While the picture of an unvaccinated child was once that of the offspring of poor and uneducated parents, “exempters” are often well educated and financially stable, and hold a host of like-minded child-rearing beliefs.

Vaccine skeptics provide differing explanations for their belief that vaccines may cause various illnesses and disorders, including autism.

Recent news that a federal vaccine court agreed to pay the family of an autistic child in Georgia who had an underlying mitochondrial disorder has led some skeptics to speculate that vaccines may worsen such conditions. Again, researchers say there is no evidence to support this thesis.

Alexandra Stewart, director of the Epidemiology of U.S. Immunization Law project at George Washington University, said many of these parents are influenced by misinformation obtained from Web sites that oppose vaccination.

“The autism debate has convinced these parents to refuse vaccines to the detriment of their own children as well as the community,” Ms. Stewart said.

While many parents meet deep resistance and even hostility from pediatricians when they choose to delay, space or reject vaccines, they are often able to find doctors who support their choice.

“I do think vaccines help with the public health and helping prevent the occasional fatality,” said Dr. Bob Sears, the son of the well-known child-care author by the same name, who practices pediatrics in San Clemente. Roughly 20 percent of his patients do not vaccinate, Dr. Sears said, and another 20 percent partially vaccinate.

“I don’t think it is such a critical public health issue that we should force parents into it,” Dr. Sears said. “I don’t lecture the parents or try to change their mind; if they flat out tell me they understand the risks I feel that I should be very respectful of their decision.”

Some parents of unvaccinated children go to great lengths to expose their children to childhood diseases to help them build natural immunities.

In the wake of last month’s outbreak, Linda Palmer considered sending her son to a measles party to contract the virus. Several years ago, the boy, now 12, contracted chicken pox when Ms. Palmer had him attend a gathering of children with that virus.

“It is a very common thing in the natural-health oriented world,” Ms. Palmer said of the parties.

She ultimately decided against the measles party for fear of having her son ostracized if he became ill.

In the late 1960s and 1970s, measles outbreaks in Alaska and California triggered strong enforcement of vaccine mandates by states, and exemption laws followed.

While the laws vary from state to state, most allow children to attend school if their parents agree to keep them home during any outbreak of illnesses prevented by vaccines. The easier it is to get an exemption — some states require barely any paperwork — the more people opt for them, according to Dr. Omer’s research, supported by other vaccine experts.

There are differences within states, too. There tend to be geographic clusters of “exempters” in certain counties or even neighborhoods or schools. According to a 2006 article in The Journal of The American Medical Association, exemption rates of 15 percent to 18 percent have been found in Ashland, Ore., and Vashon, Wash. In California, where the statewide rate is about 1.5 percent, some counties were as high as 10 percent to 19 percent of kindergartners.

In the San Diego measles outbreak, four of the cases, including the first one, came from a single charter school, and 17 children stayed home during the outbreak to avoid contracting the illness.

There is substantial evidence that communities with pools of unvaccinated clusters risk infecting a broad community that includes people who have been inoculated.

For instance, in a 2006 mumps outbreak in Iowa that infected 219 people, the majority of those sickened had been vaccinated. In a 2005 measles outbreak in Indiana, there were 34 cases, including six people who had been vaccinated.

Here in California, six pertussis outbreaks infected 24 people in 2007; only 2 of 24 were documented as having been appropriately immunized.

A surveillance program in the mid ’90s in Canada of infants and preschoolers found that cases of Hib fell to between 8 and 10 cases a year from 550 a year after a vaccine program was begun, and roughly half of those cases were among children whose vaccine failed.