We are researchers who have published analyses of nucleic acid sequence variation of hepatitis C virus (HCV) and associated virological and clinical significance. We are concerned that our investigations are hampered by the lack of a consensus nomenclature for variants of HCV and that this leads to confusion when results from different laboratories are compared. Furthermore, because there are no consistently applied criteria by which new genotypes are defined, investigators assign new type descriptions to novel sequence variants on an ad hoc basis without agreement from

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.

The seroprevalence of hepatitis B was investigated in over 12,000 subjects in six countries of Latin America: Argentina, Brazil, Chile, the Dominican Republic, Mexico, and Venezuela. Each study population was stratified according to age, gender, and socioeconomic status. Antibodies against hepatitis B core antigen (anti-HBc) were measured in order to determine hepatitis B infection. The highest overall seroprevalence was found in the Dominican Republic (21.4%), followed by Brazil (7.9%), Venezuela (3.2%), Argentina (2.1%), Mexico (1.4%), and Chile (0.6%). In all the countries an increase in seroprevalence was found among persons 16 years old and older, suggesting sexual transmission as the major route of infection. In addition, comparatively high seroprevalence levels were seen at an early age in the Dominican Republic and Brazil, implicating a vertical route of transmission.

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.

Among 256 patients with acute hepatitis A, 17 (6.6%) had a relapse of the disease between 30 and 90 days after the primary episode. We studied 7 of these patients. Serologic testing showed mean alanine aminotransferase levels of 1668 IU/L during the acute stage, 107 IU/L during the early convalescence, and 1027 IU/L during the relapse. Tests for IgM antibody against hepatitis A virus were positive in the 7 patients at the onset of disease, with decreasing levels in 3 of the 4 patients tested during the evolution of the illness. Stools collected during the relapse phase showed hepatitis A virus by immune electron microscopy, radioimmunoassay, and molecular hybridization using a 32P-labeled cDNA-hepatitis A virus probe. Stools collected from 4 of these patients 6 to 12 months after the onset of disease were negative for the virus. The finding of hepatitis A virus in the stool of these patients during the relapse phase strongly implicates hepatitis A virus as the causative agent of the clinical relapse.