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.

Anti-HIV-1 antibody testing using modified gelatin particle agglutination: a large field study.

Anti-HIV testing using gelatin particle agglutination (GPA) assay was investigated in parallel with ELISAs from routine service at Siriraj Hospital. In the first strategy, 174,032 sera from a patient population with an HIV-1 seroprevalence of 13.72 per cent were assayed using reduced volumes of GPA reagents, giving a cost reduction of 40 per cent. In the second strategy, 90,560 pregnant women and 48,936 emigrant workers with an HIV-1 seroprevalence of 2.2 per cent and 0.3 per cent, respectively, were tested in pools of 4 sera using the manufacturer's recommended volumes, giving a cost saving of 67 per cent. Overall, the sensitivity and specificity were almost identical with standard methods. Thus, parallel use of either modified GPA might be considered appropriate when testing large numbers of samples. However, both modified versions of GPA are not recommended as the first assay for diagnostic or blood bank screening especially in high prevalence of HIV infection.

Microbial killing activity of peracetic acid.

In vitro killing activity of peracetic acid (Perasafe) at a concentration of 0.26 per cent w/v was tested against Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Salmonella paratyphi A, Acinetobacter baumannii, Sternotrophomonas maltophilia, Enterococcus faecium, Enterococcus faecalis, methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis spore, Mycobacterium tuberculosis and human immuno-deficiency virus type I. Exposure to Peracetic acid (0.26% w/v) for 10 minutes resulted in massive killing of all the aforementioned organisms and spore.

Application of HIV-1-green fluorescent protein (GFP) reporter viruses in neutralizing antibody assays.

We made reporter HIV-1 DNA constructs carrying green fluorescent protein (GFP) gene and exchangeable env of subtype E. The recombinant constructs were used to produce infectious reporter viruses, which induced infected cells to emit green fluorescent light and rendered them easily detectable at single cell level. Because the env in this construct can be easily exchanged, viruses with different antigenic epitopes can be made. We used these reporter viruses to set up a neutralizing antibody assay based on fluorescence reduction by flow cytometric measurement. The result of this new assay correlated with the standard infectivity reduction assay using primary isolates. Because this new assay is faster and much less costly than the standard assay using a p24 endpoint and can be performed in peripheral blood mononuclear cells (PBMC), it provides a useful tool for analysis of HIV-1 immune responses.

The reference range of CD4+ and CD8+ T-lymphocytes in healthy non-infected infants born to HIV-1 seropositive mothers; a preliminary study at Siriraj Hospital.

The results of CD4+, CD8+ T-lymphocyte values as percentage, number, and ratio were studied in infants aged 1 to 29 months. The 283 subsequent blood samples from 89 infants born to HIV-1 seropositive mothers were investigated. From 208 sequential samples of 70 healthy non-infected infants, the reference values of CD4+ and CD8+ T-lymphocytes have been established and compared to Caucasian reference values. The results were analysed in 4 difference age groups (1-5, 6-11, 12-17 and > or = 18 months). At age 12 months, CD4 number and percentage declined significantly while CD8 percent increased. At age 6 months CD4/CD8 ratio decreased. Of 19 infected infants CD4+ percentage and number as well as CD4/CD8 ratio declined at age 6 months and showed significant differences from uninfected infants. A significantly elevated CD8 percentage was demonstrated in infected infants at age of 12 months. In 9 infants who showed symptoms at age 6-18 months, the CD4 and CD8 values were different from the reference range and 6 of 9 patients showed lower CD4 percentage, CD4 number and reversed CD4/CD8 ratio before the symptoms appeared. In 10 infants who were asymptomatic at age 18 months, there was no evidence of immunosuppression at age 6 months or before. After age 6 months, lymphocyte subset values of some asymptomatic infected children were beyond the reference range. These preliminary findings should be very useful for monitoring children born to HIV infected mothers. The results of CD4+ and CD8+ T-lymphocytes in uninfected infants could be used as reference values for the Thai and other Southeast Asian pediatric populations.

Immune status in congenital infections by TORCH agents in pregnant Thais.

A cross-sectional, sero-epidemiological survey of the prevalence of antibodies to TORCH agents during various stages of gestation revealed an overall rate of 13-15 percent having antibodies to Toxoplasma gondii; 85-87 percent, to rubella ; 79-81 percent, to herpes simplex virus (HSV); 100 percent, to cytomegalovirus (CMV); 82-86 percent, to human herpes virus type 6 (HHV-6); 1-2 percent, to hepatitis C virus (HCV). None of human T lymphotropic virus type I (HTLV-I) antibody was detected, and a prevalence of hepatitis B surface antigen (HBsAg) was 6 percent. Although a tendency was noted towards an increase of antibody detection to each TORCH agent as gestation progressed, a statistically significant increase in antibodies titer and specific IgM antibody was found with regard to CMV. These results suggest an increase in CMV infection or reactivation during pregnancy whereas an increase in the other TORCH infections was not obvious.

V3 peptide enzyme immunoassay for serotyping HIV-1 infected pregnant Thais.

Previous molecular epidemiological studies show that at least 2 subtypes of HIV-1 circulate in Thailand. HIV-1 subtype B or Thai genotype B was associated with an early epidemic and was prevalent in intravenous drug users. Meanwhile, HIV-1 subtype E or Thai genotype A was becoming widespread among heterosexuals. We studied the HIV subtypes of 161 HIV-1 seropositive pregnant women. Of these, 143 pregnant patients (88.8%) tested positive for subtype E alone and 8 women (5.0%) had evidence of infection with subtype B alone. There was serologic evidence of infection with a mixture of subtypes in 7 women while the infecting subtype could not be identified in the remaining 3 women. This result agrees with previous information that subtype E predominates in Thai heterosexuals.

Detection of HIV-1 proviral DNA by polymerase chain reaction: a preliminary study in Bangkok.

Nested polymerase chain reaction (nested PCR) was used to separately amplify part of gag, pol, and env genes of human immunodeficiency virus type 1 (HIV-1) to evaluate that primer specific to either gag (SK380/390&SK38/39), pol (JA17/18&JA19/20), or env (JA9/10&JA11/12) genes is suitable for HIV-1 PCR based diagnosis in Thailand. The positive PCR results in 70 HIV-1 infected adults are 100, 97, 89 per cent and in 75 HIV-1 infected infants are 100, 94, 74 per cent by gag, pol, env primer, respectively. The specificity of all three primer sets is 100 per cent. The unamplified samples by pol and env primers were identified as HIV-1 subtype E by PELISA method. False negative in HIV-1 PCR based diagnosis caused by high genetic variation of HIV-1 can be overcome by using several primer sets as shown in this study.

Prevalence of human herpesvirus 6 in Thai people and its correlation with human immunodeficiency virus type 1 infection.

Human herpesvirus 6 (HHV-6) is a human herpesvirus isolated from patients with various lymphoproliferative disorders and acquired immunodeficiency syndrome (AIDS). The prevalence of HHV-6 infection and its correlation as a cofactor in pathogenicity of HIV infection was investigated in serum samples from 365 healthy volunteers at various age groups, 50 persons at risk for HIV-1 infection, and 90 HIV-1 seropositive individuals. Sera were screened and titrated for antibodies against HHV-6 by a standard indirect immunofluorescence assay on an acetone fixed HHV-6 infected HSB2 cells. The data show high prevalence of HHV-6 in Thailand (71.7%) and the infection is acquired early in life. Prevalence of anti-HHV-6 IgG antibodies was not strikingly different among people at risk for HIV infection, asymptomatic HIV-1 infected cases, and aged-matched controls with low risk for HIV-1 infection. The AIDS cases showed high titers of anti-HHV-6 IgG antibody and high rates for presence of anti-HHV-6 IgM antibody (33.3%) which suggests higher prevalence of HHV-6 infection by either reactivation of an earlier HHV-6 infection or a new primary infection.

Serum alanine transaminase levels in hospital personnel and effect before and after hepatitis B vaccination.

Alanine transaminase (ALT) levels in healthy hospital personnel were studied. ALT levels in pre and post vaccinated sera were compared. In this study, all sera showed normal values of ALT, lower than 36 IU/L. Hepatitis B vaccination did not cause any change.

Etiology of diarrhea in measles.

Thirty-six measles cases with diarrhea were studied with two age and sex matched control groups, measles without diarrhea (75 cases) and acute diarrhea (70 cases). Bacterial pathogens were isolated from 5 out of 36 (13.9%) in measles with diarrhea but rotavirus, coronavirus and parasites were not detected in any case. The bacterial and viral etiology of measles with diarrhea were statistically significant different from the acute diarrhea group (p less than 0.005) and p less than 0.01 respectively) but not from the measles without diarrhea group (p greater than 0.05). 83.3 per cent of cases had diarrhea during 4 days before and after the appearance of rash. Watery diarrhea was frequently observed in this study (63.9%). Although measles virus was not identified in stools, data from this study suggested that measles may be the viral agent causing diarrhea. Watery stools are often observed and the presence of faecal white blood cell may be seen.

High prevalence of delta virus infection in Thai intravenous drug abusers.

The prevalence of antibodies to delta virus (anti-delta) in the selected groups of hepatitis B surface antigenemia population was investigated. The subjects were 84 intravenous drug abusers; 20 chronic hepatitis, 12 cirrhosis, 6 primary hepatocellular carcinoma and 46 asymptomatic healthy carriers. Anti-delta was detected in 65.48% of intravenous drug abusers, 11.11% of chronic active hepatitis and 8.33% of cirrhosis cases. None of asymptomatic carriers had anti-delta. In addition, 51 acute icteric hepatitis B patients who were positive for HBs Ag and 20 IV drug abusers positive for anti-HBc only (HBsAg and anti-HBs negative) were negative for anti-delta.

Rotavirus in pediatric diarrhoea at Siriraj Hospital, Bangkok, Thailand.

Between June 1982 and May 1983, rotavirus was found in 29% of 248 pediatric patients between 1 month to 5 years of age at Siriraj Hospital, Bangkok, Thailand. Among 413 household contacts, RV was detected in 9 (2%) of whom 6 developed diarrhoea. RV was not found in age-matched healthy controls. In a serological study, the serological response was 81% in rotavirus diarrhoea cases (17 out of 21) by ELISA. By the ELISA blocking test, the seroconversion rate was only 29.6% in rotavirus diarrhoea cases (8 out of 27) and in others, 2 out of 71 cases (2.6%) who also showed serological response did not have rotavirus in their stools. This study indicates role of rotavirus in causing acute diarrhoea in young children, suggests a guideline for diagnosis and management of the patients. The rotavirus immunization should be considered if the vaccine becomes available in the near future.