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Surveillance Summary Viral Hepatitis -- 1984

Information on viral hepatitis is obtained through two surveillance systems. Incidence data are collected from cases reported to the CDC National Morbidity Reporting System by each state and territory. The number of cases, age of patient, and date reported of each type of hepatitis as classified by physician's diagnosis appear in the Morbidity and Mortality Weekly Report (MMWR) and the MMWR Annual Summary. Serologic and epidemiologic data pertaining to risk factors of disease acquisition are obtained from the Viral Hepatitis Surveillance Program (VHSP), a totally separate voluntary reporting system operated by the Hepatitis Branch, Division of Viral Diseases, Center for Infectious Diseases, Centers for Disease Control. Morbidity Trends Based on Cases Reported to the MMWR Figure 1 shows the changes in incidence of reported cases of all hepatitis since 1955 and by type since 1966. In 1984, the reported incidence of hepatitis B surpassed that of hepatitis A for the second consecutive year. Of 57,557 cases of viral hepatitis reported to the MMWR in 1984, 38% were reported as hepatitis A; 45%, as hepatitis B; 7%, as hepatitis non-A, non-B; and 10%, as unspecified hepatitis. Virtually no change occurred in the reported incidence of hepatitis A, while there were slight increases in the reported incidence of hepatitis B and hepatitis non-A, non-B. Combined with a decline in the rate of unspecified hepatitis, these changes have resulted in a nearly constant overall rate of viral hepatitis.

In 1984, states in the west and southwest regions continued to report high rates of hepatitis A. Historically, the major contributing factors to these high rates have been transmission of hepatitis A in day care and sustained community-wide outbreaks due to person-to-person spread. Foodborne-associated outbreaks of hepatitis A often account for large year-to-year fluctuations in hepatitis A rates. The states with the highest rates of hepatitis B are clustered primarily on the east and west coasts as in previous years. Non-A, non-B hepatitis has been a separate reportable disease category in the MMWR since 1982. The low reported rates for this disease are believed to be due to incomplete serologic testing and underreporting.

Persons in the 20- to 29-year age group continue to have the highest rates of both hepatitis A and hepatitis B. The risk of acquiring hepatitis A appears to have declined in persons of all age groups except those less than 15 years of age. Some of this decline may be due to increased use of available serologic tests which may have resulted in reclassification of the type of hepatitis occurring in older persons.

Although persons under 15 years of age still experience low rates of hepatitis B infection, the risk of acquiring this disease continues to increase for all other age groups. Persons in the 15- to 39-year age groups tend to be in the high-risk categories (i.e., health care workers, parenteral drug abusers, and homosexual men) for acquiring hepatitis B. Viral Hepatitis Surveillance Program

Since 1980, the VHSP has received reports on approximately half of the cases reported to the MMWR. CDC's ability to accurately analyze and interpret nationwide trends and patterns, identify high-risk groups, and determine mechanisms of transmission for each type of hepatitis depends on (1) the local medical community's utilization of the appropriate serologic tests to distinguish between the different types of hepatitis and (2) the voluntary cooperation of the state and local health departments in completing and submitting the VHSP forms. Non-A, non-B hepatitis is now a separate reportable disease category, and since this type of viral hepatitis remains a diagnosis of exclusion, serotesting is even more important. Differentiation of any of the types of viral hepatitis based on clinical or epidemiologic characteristics alone is no longer acceptable since there is considerable overlap between the different types of hepatitis with respect to these characteristics.

The number of cases reported to the VHSP was 24,613 in 1984, representing 43% of the cases reported to the MMWR in the same year and down from 47% in 1983. Reporting of cases to the VHSP is not consistent among states because, while many states reporting to the MMWR also report to the VHSP, many of the states do not. The percentage of agreement in reporting between the MMWR and the VHSP, however, is not necessarily a measure of the actual completeness of reporting from a particular state. Despite the difference in numbers, the cases reported to the VHSP are similar to those reported to the MMWR with respect to the relative frequencies of the different types of hepatitis as well as the age distribution of the cases.

While serologic tests for diagnosing hepatitis B, including hepatitis B surface antigen (HBsAg), have been available since the early 1970's, a laboratory test for IgM antibody to hepatitis A virus (IgM anti-HAV) has only been available since 1981. The use of these two serologic tests to distinguish between the different types of viral hepatitis has increased over the past 4 years. The tendency for physicians to use both tests has increased from 27% in 1981 to 64% in 1984, while the frequency with which HBsAg is used as the only serologic test has decreased from 43% to 19%. Copies of the entire Hepatitis Surveillance Report Number 50 (issued March 1986) are available from the Hepatitis Branch, Division of Viral Diseases, Center for Infectious Diseases, Centers for Disease Control, Atlanta, Georgia 30333, telephone number (404) 321-2342.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.


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**Questions or messages regarding errors in formatting should be addressed to mmwrq@cdc.gov.

 
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