Hepatitis B

The incidence of acute hepatitis B virus (HBV) saw a decline throughout the 1980s and early 1990s. This was the consequence of both a decrease in incidence among homosexual men (from 20% to 7%) due to safe sex education for HIV transmission, as well as a decrease in incidence among children and adolescents (from 8.5 cases to 2.1 cases per 100,000 people) due to the initiation of the HBV vaccination in 1991.¹ However, the incidence of HBV among adults has increased since 1999.² The most common risk factors for HBV infection include injection drug use, sex with multiple partners, and men having sex with men. Sexual transmission is the major mode of transmission in developed countries and accounts for more than 50% of acute HBV infection in the United States.³ Although the risk of chronic HBV infection after acute exposure is only 1–5% when infection occurs in adulthood, approximately 1.2 million individuals have chronic HBV in the United States and are sources of infection to others.⁴ The risk of HBV transmission from those chronically infected is thought to be highest among those who are hepatitis B e antigen (HBeAg)-positive and those with elevated HBV DNA levels.⁵ It is recommended that spouses and steady sex partners of those with chronic HBV be vaccinated and follow safe sex practices to prevent sexual transmission of the disease. Patients treated with interferon and/or antivi-rals with adequate response, as demonstrated by hepatitis B e antibody (HBeAb)-seroconversion and undetectable serum HBV DNA levels, are generally accepted to be no longer infective to others. The case we present challenges the accuracy of this principle.

Case Report

A 37-year-old man from Texas living in New York City was referred to our liver clinic for management of HBV. A homosexual male in a monogamous relationship with his partner, he denied any history of occupational exposure or blood transfusion. He recalled a prior HBV vaccination in 2000.

The patient had initially presented to his primary care physician in Texas in November of 2005 for symptoms of jaundice, pruritus, fever, and joint pain. His limited physical examination was significant for scleral icterus, and his laboratory work-up at that time was significant for transaminitis (aspartate aminotransferase [AST] of 1,081 IU/L, alanine aminotransferase [ALT] of 1,831 IU/L), hyperbilirubinemia (total bilirubin of 8.6 mg/dL), as well as alkaline phosphatase of 283 IU/L, lactate dehydrogenase of348 IU/L, and gamma glutamyl transferase of375 IU/L. His hepatitis serologies tested hepatitis A antibody immunoglobulin (Ig)M-negative, hepatitis B surface antigen (HBsAg)-positive, hepatitis B core antibody (HBcAb)-positive, a hepatitis B surface antibody (HBsAb) level of less than 3.0 mIU/mL, HBeAg-positive, and hepatitis C virus antibody-negative, all of which are consistent with acute hepatitis B infection. His HIV test was negative. Repeat laboratory examinations 1 week and 1 month later demonstrated worsening transaminitis (AST of 1,400 IU/L rising to 1,625 IU/L and ALT of 1,970 IU/L rising to 2,111 IU/L). HBeAb was found to be negative. The patient was treated with hydroxyzine (Vistaril, Pfizer) and cholestyramine (Questran, Bristol-Myers Squibb) for symptomatic relief.

At the beginning of May 2006, the patient presented with recurrent symptoms to The Mount Sinai Faculty Practice Associates, where his partner was being followed and treated for chronic HBV with adefovir (Hepsera, Gilead) and lamivudine (Epivir, GlaxoSmithKline). During the initial evaluation, the patient recalled a discrete incident of condom breakage during anal receptive intercourse with his partner in August 2005. He otherwise reported adherence to safe sex practices with his partner and denied having sex outside of the relationship. Although the time course from condom breakage to initial presentation of symptoms was consistent with the incubation time of acute HBV, his partner had a documented undetectable serum viral load at that time (6/05: HBV DNA <100 IU/mL, HBeAg nonreactive, HBeAb reactive; 11/05: HBV DNA <100 IU/mL, HBeAg nonreactive, HBeAb nonreactive).

On physical examination, our patient was anicteric and revealed borderline hepatomegaly. His hepatitis serologies were unchanged, and his HBV DNA level measured 58,900,000 IU/mL. Laboratory findings were otherwise significant for AST of 1,010 IU/L, ALT of 2,423 IU/L and bilirubin within normal limits. By his second visit on May 4, 2006, his aminotransferases had started to trend down and his HBV genotype was found to be type A without resistance to polymerase inhibitors. Precore and basic core promoter mutations were not found. Genotyping of the patient's partner was attempted at this time but could not be performed, as his serum viral load remained undetectable. The patient was started on 1 mg of entecavir (Baraclude, Bristol-Myers Squibb) once daily at this point.

As of follow-up on June 26, 2006, the patient's AST and ALT measured 38 IU/L and 48 IU/L, respectively, and his HBV DNA level measured 283 IU/mL. The patient remains on treatment with entecavir.

Discussion

If HBV transmission to the patient occurred as described above, via exposure to the semen of a chronic HBV carrier with an undetectable serum viral load, it raises the question: do infective quantities of HBV DNA remain present in semen after HBV DNA serum levels become undetectable as a result of antiviral treatment?

Facets of this issue were previously addressed in the mid-1980s, independently, by Jenison and associates,⁶ Fagan and colleagues,⁷ and Davison and coworkers.⁸ Jenison and associates performed a quantitative analysis of HBV DNA levels in the saliva and semen of 15 chronically infected homosexual men via molecular hybridization techniques and southern blot analysis. HBV DNA levels were detected in the saliva of 8 patients (10⁵–10⁷ virions/mL) and in the semen of 3 patients (10⁶–10⁷ virions/mL). He concluded that “the presence of relatively high concentrations (10⁵–10⁷ virions/mL) of HBV particles in the saliva and semen of some carriers supports the hypothesis that these secretions play an important role in the nonparenteral transmission of HBV.”⁶ The threshold for detection of HBV DNA levels in this study was 1.0 pg/mL or 8 × 10⁵ virions/mL. All 3 patients with detectable HBV DNA levels in their semen were HBsAg-positive, anti-HBs-negative, anti-HBc-positive, and HBeAg-positive, and had more than 2,500 pg/mL of HBV DNA detected in their serum. The study did not, however, include a subset of patients whose serum HBV DNA levels were undetectable yet were semen HBV DNA-positive.⁶

In 1986, Fagan and colleagues concluded that “despite histologic remission and loss of HBV DNA from serum, the potential for transmission of HBV and reactivation of disease remain.”⁷ They cited the case of a 29-year-old homosexual man with chronic persistent hepatitis, seropositive for HBsAg, HBeAg, DNA polymerase activity, and HBV DNA for 18 months, who was enrolled in a clinical trial of treatment with a 9-week course of lympho-blastoid interferon. Approximately 7 weeks after initiating therapy, the patient developed the signs and symptoms of acute hepatitis. He subsequently cleared the HBeAg and achieved an undetectable serum HBV viral load. Six weeks later, he developed anti-HBe. His liver biopsy specimen at that time was histologically normal. However, 4 months after HBV DNA was no longer detectable in his serum, the patient's semen, saliva, and urine were examined and found to be positive for free and replicative HBV DNA. Fagan and coworkers speculated that mononuclear cells, present in both saliva and semen, were a likely source of the HBV DNA levels detected in these fluids. They also proposed that the “presence of free and replicating HBV DNA in tissues in the absence of detectable serum HBV DNA suggests that intracellular virus is protected in some way from immune surveillance.”⁷ This study utilized simple spot hybridization for quantitative analysis of HBV DNA levels, with a lower limit of detection of approximately 1 pg.⁷

In 1987, Davison and colleagues similarly concluded that sexual transmission of HBV could still occur without viral replication markers in serum. This was based on a prospective study examining the urine, saliva, and semen of 18 chronic HBsAg carriers for HBV DNA using molecular hybridization. In their study, free HBV DNA was identified in the semen of 5 patients whose sera were negative for DNA polymerase, including 2 patients whose sera were also HBV DNA-negative and 2 patients who had developed HBeAb. The presence of DNA polymerase or HBV DNA in serum was considered to be even more sensitive than the presence of HBeAg as an indication of active viral replication.⁸ The investigators subsequently concluded that “all HBsAg carriers must be assumed capable of transmitting HBV during sexual contact,” irrespective of serum HBV levels.⁸ They found that leukocytes isolated from peripheral blood contained HBV DNA. As leukocytes normally constitute saliva, semen, and urine, the authors speculated that leukocytes may be the major source of the HBV DNA identified in these fluids. The leukocytosis associated with other sexually transmitted diseases could, therefore, increase the risk of HBV infection via seminal fluid.⁸

It is worth noting that the patient reported previous vaccination against hepatitis B, as it provides an opportunity to review HBV vaccination. Hepatitis B vaccine is composed of recombinant HBsAg. The currently accepted dosing schedule, as recommended by the Centers for Disease Control (CDC), involves 3 doses at 0, 1–2, and 4–6 months. Efficacy is reported to be more than 90% in healthy adults and more than 95% in infants, children, and adolescents.⁹ The CDC does not recommend postvaccination testing for adequate antibody response after routine vaccination unless the person is immunocompromised, born to an HBsAg-positive mother, a healthcare worker, or a sex partner of a person with chronic HBV infection. Postvaccination testing, if indicated, should be completed 1–2 months after the third vaccine dose, and adequate response is 10 or more mIU/mL.¹ Booster dosing is not recommended as a part of HBV vaccination, as current data show that vaccine-induced HBsAb levels may decline over time; however, immune memory remains intact indefinitely following immunization and, therefore, people with declining antibody levels are still protected against clinical illness and chronic disease.¹ Our patient did not have documented antibody response to the HBV vaccine; however, it is unclear whether or not he actually completed the recommended dosing. In retrospect, he should have had postvaccination testing performed, as he is the sex partner of a person with chronic HBV infection.

Conclusion

These studies indicate that infective quantities of HBV DNA remain present in semen after HBV DNA levels become undetectable in serum. However, it is possible that those patients with undetectable serum HBV DNA levels cited may represent false-negatives. The threshold of laboratory testing available during this time of study was as high as 1 pg of HBV DNA, which is equivalent to 800,000 IU of HBV DNA. That leaves a large range of HBV DNA that could have been missed because of the insensitivity of the testing performed at that time. As noted by Wei-Ping and coworkers, the southern blot techniques utilized by the above investigators were tedious, time-consuming, and possibly of limited accuracy.¹⁰ In comparison, conventional polymerase chain reaction (PCR) and real-time PCR are available for detection of HBV DNA levels with threshold values of 200 and 10 copies of HBV DNA, respectively. We propose that it would be prudent to reinvestigate whether HBV DNA remains present in semen after HBV DNA levels become undetectable in serum with real-time PCR.