Issued April, 1996
Based on crude frequencies of reported risk factors, contact with another hepatitis B patient, injection drug use, and having multiple sex partners were the three most frequently reported potential sources of infection for hepatitis B patients in 1993 (Table 3). In 1993, having multiple sex partners was the most frequent potential source of infection reported. Homosexual preference was reported by 7% of hepatitis B patients during 1993. As with other types of hepatitis, several possible sources of infection were often reported for the same patient.
Seventy-two percent of the persons with hepatitis B were asked about potential risk factors commonly associated with hepatitis A that occurred within the 2 to 6 weeks prior to illness. Although these factors are generally not associated with the transmission of HBV because the incubation period is too short, health-care workers interviewing patients with hepatitis are encouraged to obtain from each patient information on all types of risk factors, both to detect newly emerging problems (as occurred with injection drug use and hepatitis A) and to ensure a complete exposure history when cases are serologically classified.
Events or conditions reported within the 6 months prior to hepatitis B illness -- such as history of dental work, surgery, acupuncture, tattooing, or other percutaneous exposures -- are not considered likely sources of sporadic infection, but are primarily useful in identifying clusters of cases at the local level.
Of three patients reported with acute hepatitis B and evidence of having responded to the hepatitis B vaccine, all three were also reported to have coinfections with acute hepatitis A. After follow-up with the reporting health department, none of these cases were found to be true candidates for breakthrough infections.
Persons who reported multiple risk factors for hepatitis B were assigned to mutually exclusive groups(2,4-6) (Table 5). As a percentage of all cases, being heterosexually active with multiple partners has replaced injection drug use as the predominant risk factor for acquisition of hepatitis B. Personal contact with another hepatitis B patient was the third most common risk factor. Of personal contacts in 1993, 68% were sexual, and 17% were nonsexual household contacts. The remaining 15% of personal contacts, classified as "other", are unclear as to specific sources because information was insufficient to determine how transmission occurred. Employment in the medical or dental field, blood transfusions, and dialysis accounted for less than 5% of cases. For those patients employed in a medical, dental or other field involving contact with human blood, 23% reported frequent blood contact in 1993, down from 36% in 1992.
To ensure that possible biases owing to artifactual decreases in reporting were minimized, the analysis of trends in hepatitis B risk factors for 1983 to 1993 was restricted to the absolute numbers of cases reported in the core states only. For these states during 1989-1993, decreases occurred in the numbers of cases attributed to injection drug use (an 83% decrease), personal contact with a hepatitis B patient (73% decrease), and multiple sexual partners (35% decrease).
The trends in risk factors associated with hepatitis B in the core states, among men and women separately, are shown in Figures 3 and 4. Among men, injection drug use has shown the largest change from 1983 to 1993. After an increase of 116% from 1983 to 1989, the numbers of cases among men attributed to injection drug use decreased by 85% (Figure 3). Safer needle-using practices, or changes in the types of drugs used (injection to noninjection) are possible reasons for this reduction. The numbers of cases among men attributable to personal contact with another hepatitis B patient has been more stable, showing a gradual decline from 1989 to 1993. For these male patients, 52% to 67% of contacts were sexual, while 13% to 20% were household contacts. Homosexual activity, the second most commonly reported risk factor, declined to its lowest level in 1993. Declines in the other reported risk factors -- health-care employment and blood transfusion -- continued through 1993.
Risk factors for women with hepatitis B displayed some of the same trends presented for men, with injection drug use as a risk factor increasing from1983 to a peak in 1989 (Figure 4), followed by a drop to pre-1983 levels. However, among women, contact with another hepatitis B patient increased more dramatically than among men and since 1990, was reported with a higher frequency than injection drug use. As with men, the majority of contacts associated with such cases have been sexual, reaching 72% in 1993, while only 11% have been household contacts.
The decrease in the percentage of female patients reporting medical and dental employment as a risk factor during 1983-1993 has been more pronounced than that for men. This decline is most probably attributable to immunization of health-care workers with hepatitis B vaccine. The percentage of cases attributable to blood transfusions has remained at low levels since 1988. The same trends in both men and women have been observed in the Sentinel Counties study.(19)
Jaundice as a clinical characteristic of hepatitis B is a common symptom in patients over 10 years of age (Table 5); 82% of all patients were reported with jaundice, regardless of age. As with hepatitis A, jaundice and other symptoms were notably less frequent for young children, suggesting more extensive underrepresentation of this age-group among reported cases. Overall hospitalization rates remained stable, showing little change since 1988, but the rates of hospitalization for patients 40 years old and older dropped slowly but steadily, from 50% in 1985 to 36% in 1993. Death as a result of hepatitis B was reported in approximately 1% of patients in 1993.
Nationwide, the incidence of hepatitis B increased by 67% from 1978 to 1985 and then declined to its lowest incidence since 1974. Since its original licensing in 1981, hepatitis B vaccine has been used in increasing quantities each year. However, the role of the vaccine in the decline of the incidence of hepatitis B varies across risk groups. From 1985 to 1989, hepatitis B among homosexual men declined more rapidly than among other risk groups, not because of vaccine use but because of behavioral changes resulting from awareness of acquired immunodeficiency syndrome (AIDS).(7) Hepatitis B also declined among health-care workers during this period, who were the largest users of hepatitis B vaccine. From 1989 to 1993, hepatitis B among injection drug users declined by 46% despite the low levels of vaccine usage in this risk group. Hepatitis B among heterosexuals decreased during this period also, possibly due to wider use of vaccine.
Vaccination programs and vaccine usage have been focused primarily on three risk groups: health-care workers who are exposed to blood, staff and residents of institutions for the developmentally disabled, and staff and patients in hemodialysis units.(9) For health-care and public safety workers, the Department of Labor in 1991 issued regulations that require employers to offer hepatitis B vaccine to persons at occupational risk of infection. However, the ability to immunize the groups that account for most of the HBV infections is severely limited for several reasons: the failure both of health-care providers and of the target populations to recognize the specific groups at high risk for infection; the difficulty in identifying persons with these high-risk behaviors before they become infected; and the difficulties in reaching these groups for the delivery of vaccine and at the appropriate time for vaccination.(7)
Adults in general, and groups such as injecting drug users in particular, are extremely difficult to access for delivery of vaccine.(11) In addition, once persons begin the lifestyles associated with a high-risk group, they may become infected before vaccine can be given. Thus, the major obstacles to reducing the incidence of HBV infection in the United States have been the difficulties in identifying persons before they become infected and vaccinating them promptly. To overcome these problems, the Immunization Practices Advisory Committee recommended in 1991 a program of routine vaccination of all infants.(9) In 1995 the same committee recommended the expansion of this program to cover 1) vaccination of all unvaccinated children aged <11 years who are Pacific Islanders or who reside in households of first-generation immigrants from countries where HBV is of high or intermediate endemicity; and 2) vaccination of all 11- to 12-year-old children who have not previously received hepatitis B vaccine.(9)
This article was provided by U.S. Centers for Disease Control and Prevention. Visit the CDC's website to find out more about their activities, publications and services.