Seroprevalence of hepatitis A virus antibody among children and young adults in Bangkok.

OBJECTIVE: To determine the prevalence of hepatitis A virus (HAV) antibodies in various age groups of healthy children and young adults who have not received the hepatitis A vaccine. METHOD: Blood samples were collected from 825 volunteers aged 1-30 years from a well baby clinic and five academic institutions in the Don Mueang area from 1998 to 1999. Serum samples were assayed for specific HAV IgG antibodies using a commercial enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: The seropositivity rate (12.4% overall) in each age group was as follows: 1-3 years, 7.7 per cent; 4-7 years, 6.6 per cent; 8-11 years, 12.4 per cent; 12-15 years, 10.7 per cent and 16-30 years, 25.9 per cent. CONCLUSIONS: In the Don Mueang area of Bangkok, the majority of children (< 16 years) do not have natural immunity against HAV. The use of hepatitis A vaccine for this population should be considered. Pre-vaccination serologic screening for HAV IgG in children may not be worthwhile.

Primary dengue infection: what are the clinical distinctions from secondary infection?

To determine the magnitude of the problem posed by primary dengue infection in children and the distinctive clinical clues that may differ from those with secondary infection, 996 children serologically diagnosed with dengue infection and admitted to the Department of Pediatrics, Chulalongkorn Hospital, Bangkok, Thailand between 1988 and 1995 were retrospectively reviewed. One hundred and thirty-nine cases (14.0%) were serologically proved to be primary dengue infection. Of these, 72 were males and 67 were females, with a mean age of 4.8 years. Common manifestations by order of frequency included fever (97.8%), hepatomegaly (71.9%), vomiting (59.0%), decreased appetite (55.4%), coryza (52.5%), drowsiness (39.6%), diarrhea (34.5%), rash (33.8%), abdominal pain (23.0%) and seizure (15.8%). The mean duration of fever before admission was 4.6 days. Common sites of bleeding were skin (41.7%), mucous membrane (14.4%) and the gastrointestinal tract (12.2%). Clinical diagnosis was categorized into dengue fever (22.3%), dengue hemorrhagic fever (60.4%) and dengue shock syndrome (17.3%). Three patients (2.2%) died. Compared with the children with secondary dengue infection (n=139), children with primary dengue infections tended to be younger, presented more commonly with coryza, diarrhea, rash and seizure; and less commonly with vomiting, headache and abdominal pain (p < 0.05). The maximal hematocrit level, the mean difference between maximal and minimal hematocrit values and the maximal percentage of neutrophils were significantly lower in the study group, whereas the maximal percentage of lymphocytes was significantly higher. Dengue fever was more common and dengue shock syndrome was less common in the study group (p < 0.05). This study has emphasized that primary dengue infection is not uncommon and is less severe than secondary infection. Clinical presentations and laboratory findings are somewhat different between the two conditions.

Seroprevalence of Epstein-Barr virus antibody among children in various age groups in Bangkok, Thailand.

There are no current data on previous Epstein-Barr virus (EBV) infections in different age groups of Thai children. This study was conducted to determine the prevalence of anti-EBV IgG antibody in healthy children of various age ranges in Bangkok, Thailand. Between June and December 1998, blood samples were collected from 425 volunteers aged 6 months to 15 years who attended a well baby clinic in the northern suburban part of Bangkok, Thailand. Serum samples were assayed for specific anti-EBV IgG antibodies using a commercial enzyme-linked immunosorbent assay kit. The percentage of children with positive anti-EBV IgG antibody increased with advancing age. The overall seropositivity rate was 72.7%. Children with anti-EBV IgG antibody were significantly older than those without the antibody. Seronegative children were reared at home significantly more frequently than seropositive children. These seroopidemiologic data will guide calculation of the appropriate age for administration of an EBV vaccine to children, when it becomes available.

Seroprevalence of anti-human herpes virus-6 IgG antibody in children of Bangkok, Thailand.

The prevalence of HHV-6 infection was surveyed by determining the presence of anti-human herpesvirus-6 IgG (Anti-HHV-6 IgG) using an ELISA method. Two hundred and ten sera collected from healthy Thai children aged between 0 to 12 years (mean +/- standard deviation = 3.35+/-3.33) indicated the prevalence of HHV-6 infection was 88.10% (185/210). Samples were classified into 7 groups, 30 samples each, according to their ages, ie, group 1: 0 - < 6 months; group 2: 6 - < 12 months; group 3: 12 - < 18 months; group 4; 18 - < 24 months; group 5: 2 - < 5 years; group 6: 5 - < 8 years and group 7: 8-12 years. The prevalence of HHV-6 infection was 63.33%, 70%, 96.67%, 93.33%, 100%, 100% and 93.33%, respectively. The mean level of anti-HHV-6 IgG among those positive for HHV-6 infection (185 samples) increased from 0 < 6 months old (17.47+/-6.32 units) to 27.57+/-8.42 units in 6 - < 12 months old, with the highest value found in the 18 - < 24 months old group (33.08+/-8.64 units). The level declined thereafter. A statistically significant difference of the mean level of anti-HHV-6 IgG among positive groups was found (p-value < 0.05). The important factor associated with HHV-6 infection was age (p = 0.002), while sex, socioeconomic status, number of children in the family and child rearing place did not show any association.

Epidemiology of invasive meningococcal disease in 13 government hospitals in Thailand, 1994-1999.

This study was conducted to elucidate the magnitude of problem and the clinical course of invasive meningococcal infection from 13 government hospitals in Thailand between 1994 and 1999. Thirty-six strains of Neisseria meningitidis were isolated from 16 blood and 24 cerebrospinal fluid specimens; 4 patients had positive culture in both blood and CSF. Of the 16 strains, 9 (56.3%) were serogroup B. Seventy-one and eighty-four percent of the isolates were susceptible to penicillin and cefotaxime/ceftriaxone respectively. Five out of six penicillin-nonsusceptible strains were found to be relatively resistant to penicillin with the MIC of 0.125 microg/ml. Of 33 patients whose medical records were available, 21 were males and 12 were females, with a mean age of 11.2 years. Fifteen patients (45.5%) presented with meningococcemia and 18 patients (54.5%) presented with meningococcal meningitis. Hypotension and purpura were found in 24.2% and 33.3% of patients respectively. The overall mortality rate was 9.1%. In conclusion, meningococcal disease is not common in Thailand, meningococcemia is a life-threatening condition whereas meningococcal meningitis is much less severe. The prevalence of meningococci relatively resistant to penicillin seems to be increasing.