The Canadian Journal of Human Sexuality

Volume 6 - Number 2 1997
Special Issue: STDs and Sexual/Reproductive Health

Published by SIECCAN
The Sex Information & Education Council of Canada

Lovers and Livers: Hepatitis B as an STD

[Français]

Martin L. Tepper & Paul R. Gully
Blood-borne Pathogens Division
Bureau of Infectious Diseases
Laboratory Centre for Disease Control
Health Protection Branch
Health Canada
LCDC Building, 0603E1
Ottawa, Ontario

Abstract:

Hepatitis B virus (HBV) infection is a sexually transmitted disease with significant health sequelae. This paper provides basic background information on HBV infection, reviews current knowledge on the epidemiology of HBV in Canada, examines the role of sexual transmission in the spread of HBV, identifies risk factors for sexual transmission, and outlines measures for prevention of HBV infection. Risk factors for the sexual transmission of HBV infection include: being a female sex partner of an infected male; being a man who has sex with men; number of years of sexual activity; number of sexual partners; anal sex; and infection with other sexually transmitted diseases. Immunization, contact tracing, and educational programs targeting high risk behaviour and consistent condom use are recommended strategies for preventing HBV infection.

Key words:

  • Hepatitis B virus, Sexually transmitted disease,  Risk factors,  Prevention, Canada

Acknowledgement:

The authors wish to thank A.S. Meltzer for permission to use, as the title of this paper, a phrase from his 1983 booklet, "The ABCs of STD: A guide to sexually transmitted diseases" by Eden Press of Montreal.

Correspondence concerning this paper should be addressed to Dr. Martin L. Tepper, Blood-borne Pathogens Division, Bureau of Infectious Diseases, Laboratory Centre for Disease Control, Health Protection Branch, Health Canada, LCDC Building, 0603E1, Ottawa, Ontario, K1A 0L2. Tel: 613-941-6087; Fax: 613-998-6413; email: martin_tepper@hc-sc.gc.ca

Background

Hepatitis B virus (HBV) is the most common of the viral hepatitis agents and a major cause of morbidity and mortality globally. HBV infection can progress to cirrhosis of the liver and hepatocellular carcinoma. The World Health Organization estimates that there are currently more than two billion people who have been infected with HBV, including 350 million who are chronically infected. Each year, about a million people die as a result of HBV infection, and over four million new acute clinical cases occur (World Health Organization, 1996).

The first recognized outbreak of HBV infection took place in Bremen, Germany, in 1883, and was linked to smallpox vaccinations contaminated with HBV (Zuckerman, 1983). Further outbreaks were reported sporadically thereafter, often related to contaminated injections. The largest outbreak of this kind occurred in 1942 and involved an estimated 330,000 American soldiers given contaminated yellow fever vaccine (Seeff et al., 1987). The important, although serendipitous, discovery of "Australia antigen" (a part of the HBV) by Blumberg, Alter, and Visnich (1965) and the separation of disease caused by the hepatitis A virus from that caused by HBV by Krugman, Giles and Hammond (1967), subsequently led to virologic and serologic breakthroughs that have resulted in an ever increasing understanding of HBV, HBV infection and HBV disease (Sherlock, 1984) (see Table 1 for the basic medical and epidemiologic features of HBV infection).

Figure 1

Annual crude rates of hepatitis B in Canada as reported by NNDRS* for 1980-1995 and for "acute hepatitis B"**, 1992-1995.

Figure 1
* NNDRS - National Notifiable Diseases Registry System
** from Tepper, 1997

Epidemiology of HBV Infection

In Canada, HBV infection has been reported nationally since 1969. These data indicate an increasing secular trend of reported HBV infection in the late 1980s followed by some reduction and levelling off in the 1990s (Health Canada, 1996) (Figure 1). However, while cautious interpretation is prudent, recent analysis in which data are restricted to "acute cases" indicates a significant decrease in such cases in the 1990s, in all jurisdictions, for both sexes, and for those aged 15 to 59 years (Tepper, 1997). The rates of reported acute infection are twice as high for males as for females, and highest in the 20-39 year age group (Tepper, 1997). National reporting does not include information on the risk factors for transmission.

The Sexual Transmission of HBV

The highest titres of HBV are found in blood. However, HBV has also been found in semen and saliva (Heathcote, Cameron, & Dane, 1974) and vaginal secretions (Darani & Gerber, 1974). Further, saliva (by injection but not oral application) and semen (by intravaginal application) have transmitted HBV infection to non-human primates (Scott, Snitbhan, Bancroft, Alter, & Tingpalapong, 1980).

Hersh, Melnick, Goyal, and Hollinger (1971) were the first to provide evidence for the sexual transmission of HBV, describing eight female cases of HBV that were linked to intimate contact with six infected males. In a more recent series of studies, Alter et al. (1986; 1989) provided strong epidemiologic evidence of heterosexual transmission. During the 1970s, it became clear that male homosexuals were at high risk for HBV, one reason why homosexuals were the prime subjects for the early HBV vaccine trials (Szmuness et al., 1980). More recently, Kingsley et al. (1990) demonstrated that among homosexual men, HBV is more easily transmitted than human immunodeficiency virus (HIV). The estimated risk of HBV transmission from a single unprotected sexual contact with an infected person is 1-3% (Hadler & Margolis, 1993). It is now accepted that, in the developed world, sexual transmission is the major recognized mode of transmission; in the developing world, while perinatal and early childhood horizontal transmission are of prime importance, sexual transmission is a significant contributor (Hadler & Margolis, 1993).

Epidemiologic studies focusing on the sexual transmission of HBV have usually examined homosexual/bisexual males, female sex trade workers, clients at STD clinics, and sexual partners of HBV infected persons. All of these groups have been found to have a high prevalence of HBV infection, past or present. Data for Ontario suggest that of acute cases of HBV in which risk factors have been identified, about one third are attributable to sexual transmission (Ontario Ministry of Health, 1995). Data on the epidemiology of acute cases of HBV infection in the Montreal area indicate that 55% are related to sexual transmission (Dion, 1994).

Data from an active surveillance study of viral hepatitis in several cities in the United States indicate that between 1982 and 1991, the distribution of risk factors for HBV infection shifted, with cases linked to male homosexual transmission and intravenous drug use decreasing, while cases linked to heterosexual transmission increased to become the most frequently identified risk category (Alter & Mast, 1994). It is noteworthy that the reduced rate of transmission among homosexual men may be due to the incorporation of safer sex practices on the part of gay men in response to the Acquired Immune Deficiency Syndrome (AIDS) epidemic. The risk factors associated with the sexual transmission of HBV are summarized in Table 2.

Prevention of Sexual Transmission of HBV

Immunization

HBV infection is the only STD for which an effective and safe vaccine is available. HBV vaccine has been available in Canada since 1982. Beginning with British Columbia in 1992, all provinces, except Manitoba, now have a universal hepatitis B vaccination program for pre-adolescents, and New Brunswick, Prince Edward Island and Northwest Territories also have a universal infant vaccination program (Tepper & Gully, 1997). The targeting of pre-adolescents for a universal vaccination program was predicated, to a large extent, on the recognition that sexual activity is an important mode of HBV transmission in Canada (Health Canada, 1994). These universal immunization programs are expected to have a significant effect on the incidence of HBV infection in the next decade as those young people who are immunized now will be protected from HBV infection during adolescence and young adulthood, a period in which sexual activity is likely.

Despite the universal immunization programs currently aimed at young people, targeted immunization of high risk groups remains important (Health Canada, 1993). These groups include sexually active homosexual/bisexual males, males and females with multiple sexual partners, those with a recent history of STD, sexual contacts of HBV carriers, and international travellers who are likely to have sexual contact with residents in areas with high levels of endemic disease. Most Canadian provinces provide publicly funded vaccine for some, but not all, of these risk groups. Reports from programs to immunize STD clinic patients at risk for HBV have documented vaccine completion rates of 24% (three doses) (Bhatti et al., 1991) and 21% (two doses) (Weinstock et al., 1995). A similar Canadian study (Yuan & Robinson, 1994) indicated completion rates (three doses) of 47% for homosexual/bisexual men and 25% for heterosexual men. A randomized trial in Canada found that compliance with immunization among STD patients can be enhanced with more aggressive follow-up (telephone and mail as opposed to mail only) (Sellors et al., 1994). A 1990 STD clinic study in the U.S. indicated that if vaccine was offered to all of an estimated 18,000 new STD encounters who visited the clinic each year, 636 infections would be prevented annually at a cost of $875 (U.S.) per infection prevented (Weinstock et al., 1995).

Safer Sex

The recommendations for safer sex made in light of the HIV epidemic apply equally to the sexual transmission of HBV (Health Canada, 1995). Laboratory testing indicates that latex condoms provide an effective barrier to HBV (Minuk et al., 1987). A study by Rosenblum et al. (1992) of female prostitutes found an association between spermicide and/or diaphragm use and a reduction in risk of HBV infection. However, the efficacy of the spermicide nonoxynol-9, included on some condoms, in inactivating HBV is not known.

Unprotected anal intercourse appears to be a particularly high risk behaviour for acquisition of HBV infection, and unprotected vaginal intercourse also carries a demonstrated risk. As a result, STD prevention education programs that emphasize the reduction of high risk behaviours and promote the consistent use of condoms, particularly those targeted at specific STD risk groups, may be beneficial in preventing the spread of HBV in the Canadian population.

Contact Tracing

It is not known whether contact tracing is a cost-effective method for HBV prevention or which tracing method is most efficient (Munday, McDonald, Murray-Sykes, & Harris, 1983; Oxman et al., 1994). Nevertheless, HBV contact tracing offers a number of benefits and is a recommended practice in Canada (Millson et al., 1994; Health Canada, 1995). Currently, HBV contact tracing is frequently practiced by public health units in Canada (Rasooly, Millson, Frank, Naus, & Coates, 1994). Tracking HBV contacts allows for the identification of a possible source for the index patient and for breaking a "chain of transmission". It also provides an opportunity to counsel susceptible contacts about risk reduction, and to recommend Hepatitis B Immune Globulin (HBIG) and/or vaccine to reduce the risk of infection among contacts (Health Canada, 1993).

Conclusion 

Our current knowledge about the virology, epidemiology, serology, and clinical course of HBV infection is considerable. Health care providers need to consider HBV infection as an STD with significant health sequelae. The prevention of HBV requires intervention from both the public health and clinical care sectors. Programs dedicated to immunization, contact tracing, and education to reduce high risk behaviours and promote condom use can provide the basis of an effective strategy to combat the spread of HBV in Canada.

Table 1 - Basic Features of Hepatitis B Virus Infection

Agent:
  • hepatitis B virus (a DNA hepadnavirus)
Reservoir:
  • humans (although primates are susceptible)
Occurrence:
  • worldwide with particularly high endemicity in Africa and the Far East
Transmission:
  • vertical (especially in areas of high endemicity)
  • percutaneous (e.g., injection drug use, needlestick)
  • sexual (both heterosexual and homosexual)
Incubation Period:
  • usually 45-180 days (average: 60-90 days)
Period of Communicability:
  • all persons who are HBsAg positive (those with HBeAg are the most infectious)
Clinical Disease:
Acute Infection:
  • often asymptomatic (90% of infected children; 50-70% of infected adults); symptoms: anorexia, nausea, jaundice; case-fatality rate: less than 1%
Chronic Infection (carrier state):
  • development varies with age at initial infection (90% of those who acquire infection in the first year of life become carriers; 25-50% in 1-5 year olds; 1-10% in older children and adults); can be associated with chronic liver dysfunction and hepatocellular carcinoma
Serologic Markers:
HBsAg (surface antigen):
  • detectable before clinical onset and for a variable time after (weeks to months; years for carriers); marker of active viral replication (i.e.,infectious)

 

antiHBs (antibody to HBsAg):
  • appears as HBsAg disappears or as the only marker after immunization
antiHBc (antibody to core antigen):
  • appears at the onset of illness and persists indefinitely
antiHBc IgM (antibody to core antigen, IgM fraction):
  • appears in high titre during acute infection and usually disappears within 6 months; usually indicates recent infection
HBeAg (e antigen):
  • a marker for particular infectiousness
Specific Prevention:
  • hepatitis B immune globulin (passive immunization)
 
  • hepatitis B vaccine (active immunization)
Specific Treatment:
  • interferon alpha (for some cases of chronic hepatitis B)

Source: Benenson, A. (Ed.) (1995). Control of Communicable Disease Manual, (16th ed.). Washington, DC: American Public Health Association.

Table 2 - Risk Factors for the Sexual Transmission of HBV

Female heterosexual

Transmission from infected men to women is about three times more efficient than from infected women to men (Roumeliotou-Karayannis, Papaevangelou, Tassopoulos, Richardson, & Krugman, 1985).

 

Anal intercourse, analingus

Studies of homosexual men indicate that anal intercourse, both insertive (Schreeder et al., 1982; Kingsley et al., 1990) and receptive (Schreeder et al., 1982; Osmond et al., 1993) is associated with an increased risk of HBV infection. Rosenblum et al. (1992), in a study of female prostitutes, found that women who engage in anal intercourse are at increased risk of HBV infection. Anal-oral contact is also linked to HBV transmission (Schreeder et al., 1982). The rectal mucosa is particularly prone to trauma with resulting bleeding, thus enhancing the risk to the receptive or the insertive partner depending on which is HBV infected. Among homosexual men with persistent HBV infection, asymptomatic rectal bleeding is frequent and HBV can be recovered from the rectum in many such cases (Reiner et al., 1984).

 

Past or current infection with other STDs

A history of or increased frequency of infection with other STDs has been shown to be a risk factor for HBV infection (Frosner, Buchholz, & Gerth, 1975; Mele et al., 1988; Peterson, Clemens, Bock, Friese, & Hess, 1992; Osmond et al., 1993; Hart, 1993; Hart et al., 1993). For example, persons infected with syphilis (Rosenblum, Hadler, Castro, Lieb, & Jaffe, 1990; Rosenblum et al., 1992; Osmond et al., 1993; Heng et al., 1995) or HIV (Kingsley et al., 1990; Rosenblum et al., 1992) are at increased risk for HBV. Conversely, serologic evidence of past or current HBV infection may be a marker for other STDs, especially HIV (Hart, 1993; Ter Meulen et al., 1989).

 

Number of years of sexual activity

The number of years of sexual activity has been associated with increased risk of HBV infection for both heterosexuals (Baddour, Bucak, Somes, & Hudson, 1988), including female prostitutes (Frosner, et al., 1975), and male homosexuals (Szmuness et al., 1975; Schreeder et al., 1982). In Canada, Romanowski and Campbell (1994) found that both male and female heterosexuals with more than 7 years of sexual activity were 2-3 times more likely to have HBV infection markers than those with less than 8 years (although the difference was not statistically significant).

 

Number of sexual partners

For both heterosexuals and homosexuals, increasing rates of HBV infection are associated with increasing numbers of recent and lifetime sexual partners (Schreeder et al., 1982; Alter et al., 1986; 1989; Rosenblum et al., 1990; Osmond et al., 1993; Romanowski & Campbell, 1994; Heng et al., 1995; Siegel, Alter, & Morse, 1995). A Canadian study (Romanowski & Campbell, 1994) indicated that, among women, those with more than 10 lifetime partners were 1.9 times more likely to have been infected with HBV than those with less than 11 partners (although the difference was not statistically significant).

 

Men who have sex with men

Men who have sex with men are at increased risk of HBV (Lim et al., 1977; Dietzman, Harnisch, Ray, Alexander, & Holmes, 1977; Tedder et al., 1980; Mele et al., 1988; Hart, 1993). Two Canadian studies including homosexual/bisexual men attending STD clinics found prevalence rates for past or present HBV infection of 18% and 39% which are 3.6 and 4.2 times, respectively, the prevalence among heterosexual males attending the clinics (Romanowski & Larke, 1983; Yuan & Robinson, 1994).

 

HBeAg positivity of the source case

Perrillo et al. (1979) found that the rate of infection among spouses and sexual contacts of HBeAg positive carriers was three times that of similar contacts of carriers without HBeAg.

 

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