Hepatitis B virus DNA in blood donors with anti-HBc as a possible indicator of active hepatitis B virus infection in Yucatan, Mexico.

Hepatitis B virus (HBV) may be present in serum even when negative for HBV surface antigen (HBsAg). If routine screening of sera for anti-HBV core antigen (anti-HBc) is not done, low-level HBV viraemia may not be identified. A study was done on the presence of HBV DNA in serum samples from Mexican blood donors negative for HBsAg. Sera from 158 volunteer blood donors, negative for HBsAg and anti-HBs, but positive for anti-HBc, were analysed using nested polymerase chain reaction (PCR). HBV DNA was detected in sera from 13 (8.23%) of the 158. Specificity of the PCR-amplified products was corroborated using Southern blot. Single strand conformation polymorphism (SSCP) analysis showed identical SSCP-banding patterns for all 13 PCR products, suggesting similar cDNA sequences. Occult HBV infection was observed in approximately 8% of anti-HBc only donors. The absence of HBsAg in the blood of apparently healthy individuals may not be sufficient to ensure lack of circulating HBV, and blood containing anti-HBc only may be infectious until proven otherwise.

[Antibodies against human immunodeficiency virus in a male homosexual population]. / Anticuerpos contra el virus de inmunodeficiencia humana en una población homosexual masculina.

Between August/1987, and February/1988, 60 homosexual-men from Cancun, Q. Roo, Mexico, were studied to determine the prevalence of HIV antibodies (Elisa and Western Blot). Six subjects were seropositive. No relationship was found between HIV antibodies and age, socioeconomic level or sexual intercourse with foreign subjects. The number of sexual partners/month, and the number of sexual intercourse/month were associated with the presence of HIV antibodies. Bisexual practices were found in 43 percent of all the group. Two subjects with HIV antibodies were classified in the phase II of HIV infection, one in phase III, two in phase IV-A and one more in phase IV-c2.