The objectives of this study were to investigate the prevalence of infections with hepatotrophic viruses in an anti-human immunodeficiency virus (HIV)-positive population from Buenos Aires and to compare it among the main risk groups for HIV infection. Four hundred and eighty-four consecutive patients attending the HIV outpatients clinic were studied: 359 men and 125 women, median age 29 years (range 16-67 years); 35.5% had presented acquired immune deficiency syndrome (AIDS)-defining conditions. Two hundred and thirty-four patients were intravenous drug users (IVDU), 99 had homosexual and 142 heterosexual preference, seven had received blood transfusions and two had no risk factors. Hepatitis B surface antigen (HBsAg), and antibodies to hepatitis B core antigen (HBcAb) and to hepatitis C virus (anti-HCV) were investigated in all patients; antibodies to HBsAg (HBsAb) and IgG antibodies to hepatitis D virus (anti-HDV) in all HBcAb-positive patients; hepatitis B e antigen and antibodies to HBeAg (HBeAg) in all HBsAg-positive patients; IgG antibodies to hepatitis A virus (anti-HAV) in the first 307 patients; and IgG antibodies to hepatitis E virus (anti-HEV) in the first 91 patients. As control groups, contemporary voluntary blood donors were studied for prevalence of HAV, HBV, HCV and HEV. The percentages of HBcAb, HBsAg, anti-HCV and anti-HEV (58.5, 14.5, 58.5 and 6.6%, respectively) were significantly higher in anti-HIV-positive patients than in control groups (3.2, 0.5, 1.0 and 1.8%, respectively) (P = 0.000). The prevalence of HBcAb was significantly higher in IVDU (72.6%) than in heterosexuals (33.8%) (P = 0.0001) and in homosexuals (59.6%) (P = 0.0189). The percentage of HBsAg was significantly higher in IVDU (19.2%) than in heterosexuals (6.3%) (P = 0.0004). Anti-HCV was significantly higher in IVDU (92.3%) than in homosexuals (14.1%) and in heterosexuals (33.1%) (P = 0.000 in both cases). The prevalence of anti-HDV was relatively low (1.9%). There was no difference in the percentage of anti-HAV between HIV-positive and negative subjects. In conclusion, there is a high prevalence of HBV and HCV infections in HIV-positive patients from our area. Drug use is the main route of transmission, but prevalence of HCV in patients with, probably, sexually acquired HIV infection is also higher than in the control group. The increased prevalence of HEV infection in HIV-positive individuals is another provocative finding that warrants further study.

In Argentina, a country considered non-endemic for hepatitis E virus (HEV) infection, serologic evidence of HEV infection has been observed in different human population groups. In other countries, a high degree of genetic relatedness has been observed between human and swine HEV genotype 3 sequences, suggesting zoonosis as one probable route of infection. This is the first identification of swine HEV in South America. HEV RNA was detected and sequenced in the ORF 1 and ORF 2 regions from swine fecal samples from a herd located in Pergamino, in the province of Buenos Aires. These strains all group into genotype 3 and exhibit a close relationship to two novel HEV variants previously identified in Argentina from sporadic acute cases of non-A to -C hepatitis in humans. In addition, using a modified commercial ELISA, the presence of anti-HEV antibodies was surveyed in five provinces across the country and all five showed a prevalence of HEV antibodies, ranging from 4% to 58%. The results suggest that swine could be an important reservoir for virus transmission in Argentina as has been suggested for other non-endemic areas. The Argentine human strains and swine strain described in this article seem to be closely related to a human Austrian strain, suggesting a potential European origin of HEV infection in these cases.

Our results suggest that viral factors could be involved in the severity of the clinical presentation of HAV infection in children in Argentina.

Hepatitis A, a vaccine preventable disease, is now of transitional or intermediate endemicity in Argentina, as the epidemiologic pattern of the disease has shifted with improvements in living conditions in some parts of the country. Increase in the susceptibility of older children and adults has led to increasing disease incidence. Molecular epidemiology has played an important role in the understanding of HAV infection by identifying modes of spreading and by permitting the monitoring of changes in circulating virus brought about by prevention programs. South American isolates characterized are limited. Eighty-two sporadic and outbreak isolates from Argentina were sequenced in the VP1/2A region of HAV genome over a 9-year period. All the isolates belonged to subgenotype IA. All our sequences grouped into two big clusters. Apparently, at least two lineages have been co-circulating in the same place at the same time. Despite great genetic variability, few point amino acid changes could be deduced. Four sequences showed an Arg --> Lys substitution at 1-297 which characterized the genotype IB at the amino acid level. Many isolates carried a conservative amino acid substitution Leu --> Ile at position 42 of the 2A domain, previously described as a possible fingerprint of HAV sequences in Brazil. The other rare changes have been found before, except for a 1-277 Asn --> Ser substitution displayed in two isolates that has not been previously reported. Argentina recently implemented universal vaccination in 1-year-old children. Molecular tools would be useful in an active surveillance program.

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