The prevalence of viral hepatitis among the Hmong people of northern Thailand.

Sera from 269 Hmong people (102 males and 167 females, with mean age 35.4 years, range 16-63 years) were examined in order to determine the seroprevalence of hepatitis virus infection. The seroprevalence rates for HAV (hepatitis A virus), HBV (hepatitis B virus), HCV (hepatitis C virus), HDV (hepatitis D virus), HEV (hepatitis E virus), HGV (hepatitis G virus) and TTV (TT virus) infection were 87.8% (n=140), 76.0% (n=150), 2.0% (n=150), 0.7% (n=150), 6.5% (n=139), 5.3% (n=94) and 25.6% (n=121) respectively. The rate for carriers of HBV (HBsAg) was 13.8% (20.5% in males and 9.6% females) with a peak prevalence in the 21-40 year age group. A high rate of HAV seropositivity was found among the younger subjects. The rate of HEV seroprevalence was low. The prevalence of TTV-DNA was high with no difference between the sexes. HGV-RNA prevalence was low and seen primarily in males. This study indicates that the Hmong people are endemically infected with HAV and HBV infection and should be considered for targeted vaccination. The role of TTV and HGV in producing illness and hepatic disease has yet to be determined in this population.

TT virus infection in acute non-A to E hepatitis in northern Thailand.

TT virus is a novel DNA virus widely distributed in the general population. We examined the prevalence of TTV infection in a population with acute non-A to E hepatitis and in comparison groups located in Northern Thailand. The prevalence of TTV in subjects with non-A-E hepatitis was 19% (21/112), 6% (4/72) in healthy volunteers, 17% (12/72) in those with hepatitis A or B, and 17% (8/48) in hospitalized patients with non-hepatitis illnesses. A significant association with TTV infection and non-A-E hepatitis was seen in all groups (OR 3.9, p = 0.02) and in children (OR 25.8, p = 0.001). Among subjects with non-A-E hepatitis, TTV was associated with higher alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels (significant for AST, p = 0.02). Our observations suggest that TTV in our study population may be associated with non-A-E hepatitis and that children in particular may be at risk of hepatocellular injury as a result of TTV infection.

B cells are the principal circulating mononuclear cells infected by dengue virus.

Although dengue virus infects a variety of cells in vitro, little is known about cell types infected in vivo. Since blood is a readily accessible tissue, we chose to determine which circulating blood cells are infected by dengue viruses. We collected blood mononuclear cells from acutely ill dengue patients and separated the cells by flow cytometry into subsets for virus isolation. Cells were sorted into groups corresponding to the cluster designations CD3, CD14, CD16 and CD20. Virus was isolated from sorted groups by inoculation into Toxorhynchites splendens mosquitos. The majority of the virus was recovered from the CD20 or B cell positive subset. Little virus was isolated from monocytes, NK cells or T cells. Virus was isolated from B cells regardless of the age or sex of the patient, virus serotype isolated, or the patient's history of dengue virus infection. The location of cell associated virus was determined by proteolytic digestion of surface virus. There was an equal distribution of virus between the intracellular compartment and the surface of B cells. The intracellular localization of virus was confirmed by immunocytochemistry. Since this study focused on circulating cells, no inferences were made regarding infection of cells in solid tissues.