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Hepatitis C virus subtype 3a (HCV-3a) originates from Asia and has spread widely among injecting drug users as well as other patient groups in industrialized countries. HCV subtype 3a infection remains highly prevalent and frequently transmitted in the population of intravenous drug users. The objective of this study was to understand better the mechanisms of the worldwide HCV-3a epidemics in drug users. Ninety-three sera from HCV-3a-infected IDUs from France, the United States, Brazil, Argentina, and Australia were studied. Phylogenetic analyses of the non-structural 5B region showed no specific clustering according to the continent of the patient's origin. Non-exclusive clusters of viral sequences from South America, Australia, and California were observed, but topologies were not supported by strong bootstrap values. The results suggest that HCV-3a has been transmitted from a common origin through a unique worldwide epidemic that rapidly spread among drug users. Regional transmission occurred in the recent past, leading to an embryonic genetic diversification of HCV-3a among local injecting drug user population.

Group A rotaviruses are the major cause of severe gastroenteritis in young children worldwide. Because rotavirus vaccination appeared imminent, a nationwide surveillance program was organized between October 1996 and October 1998 in the largest Argentine cities. Surveillance for disease burden, rotavirus detection, and rotavirus typing was undertaken at nine locations. Results showed rotavirus to be associated with 42% of diarrhea admissions. Although the prevalent G types changed from year to year, common G types were found in 96% of the cases and were usually associated with common P types. Uncommon G types, G9 and G5, were found at low prevalence and uncommon G/P combinations occurred at almost every study site. These data suggest that a rotavirus vaccine could substantially decrease the rotavirus disease burden in Argentina, but that introduction of a vaccine should be accompanied by a concurrent surveillance system., (Copyright 2001 Wiley-Liss, Inc.)

One thousand five hundred and seventeen HBsAg carriers from different cities of Argentina were studied for the presence of anti-Delta antibody (anti-HDV) in their sera. One thousand one hundred and sixty-eight were volunteer blood donors and 349 were patients with liver disease. Different liver diseases were diagnosed by clinical, biochemical, and histological parameters. Among blood donors, 16 (1.4%) were positive for the antibody and none was Delta-antigen positive. In 130 patients with acute hepatitis, one (0.77%) was positive for anti-HDV, as well as three (2.22%) out of 135 patients with chronic active hepatitis (CAH), and three (5.77%) out of 52 patients with cirrhosis (C). No anti-HDV positive was found among seven fulminant hepatitis (FH) cases. The presence of HBeAg and anti-HBe was studied in anti-HDV positive sera; eleven (69%) volunteer blood donors were anti-HBe positive, and five (31%) were HBeAg positive. HBeAg was positive in the three CAH cases, and in one out of three C Cases with anti-HDV positive. Hepatitis Delta antigen was also positive in the hepatocytic nuclei in the three patients with C and two of the three CAH cases. The present results show that Delta infection is rare among blood donors in Argentina. A small variation without statistical significance could be found within different geographical areas. Among patients with HBsAg related liver disease, the presence of HDV markers was also low.

Sera of 155 chronic hepatitis (CH) patients in Argentina were tested for the presence of HBsAg, anti-HBs, anti-HBc, and anti-HAV. Our purpose was to define the role that both virus A and B might play in the etiology and pathogenesis of this condition. The patients were divided into two groups: group I (57) HBsAg-negative; group II (98) HBsAg-positive. The control group consisted of 1,209 healthy blood donors from Banco Central de Sangre de Rosario; 286/1,209 (24%) had viral markers for HBV. In group I, 38/57 (67%) had anti-HBs and/or anti-HBc, but none had anti-HBs alone. Group II showed a higher percentage of males (P less than 0.05). We found similar incidence of anti-HAV among group I, group II, and the control group.

Over a seven-year period, we monitored 221 patients with chronic hepatitis from two medical centers. By using the counterlectrophoresis (CEP) test to detect the presence of HBsAg and anti-HBc, or both, we established that 87.7% of them had hepatitis B infection. Serum specimens originally found negative for HBsAg by CEP were further tested by reversed passive hemagglutination (RPH), and those originally found negative for anti-HBc by CEP were further tested by radioimmunoassay (RIA). Five patients were anti-HBc-positive and HBs-Ag-negative. No sex predominance was observed, but HBsAg incidence increased with increasing age. The HBeAg antigen was detected in 46.8% of the 161 cases tested for it; the most frequent subtype found was adw (63.7%). The present findings indicate that HBV infection largely contributes to the development of chronic hepatitis in Argentinian patients.

Seventy-seven consecutive HBeAg-positive chronic hepatitis patients were studied from 1971 to 1983 to establish the seroconversion rate in the e system. Patients with less than a year of follow-up were not included in the study. Fifty-six patients with chronic active hepatitis (CAH) received immunosuppressive treatment (corticosteroids combined with azathioprine). The remaining twenty-one patients received no treatment, nine of them with chronic persistent hepatitis (CPH) and 12 with CAH. A retrospective study was performed with stored sera samples: HBeAg and anti-HBe were determined by RIA, and results were correlated with alanine aminotransferase (ALAT) levels in the same samples. The linearized seroconversion rate from HBeAg to anti-HBe was expressed as percent per patient-year. It was 9.6% in CPH patients and 8.8% in CAH patients without treatment. In CAH patients under immunosuppressive drugs it was as low as 1.1% and increased to 28.7% when treatment was withdrawn. ALAT levels were significantly lower in total seroconverted patients when compared with nonseroconverted (NS) patients, but no difference was found between partial seroconverted (PS) and NS patients. The results suggest that although immunosuppressive drug withdrawal may enhance seroconversion rate in type B CAH, delayed seroconversion and reported side effects during treatment stand against protracted usage of these drugs.