A Thai boy with hereditary enzymopenic methemoglobinemia type II.

Individuals with methemoglobin exceeding 1.5 g/dl have clinically obvious central cyanosis. Hereditary methemoglobinemia is due either to autosomal dominant M hemoglobins or to autosomal recessive enzymopenic methemoglobinemia. Four types of enzymopenic methemoglobinemia have been described. In addition to methemoglobinemia, individuals with type II, which is the generalized cytochrome b5 reductase deficiency, have severe and progressive neurological disabilities. Here we report a 3-year-old Thai boy with type II hereditary enzymopenic methemoglobinemia. He was born to a second-cousin couple. His central cyanosis was first observed around 10 months of age. His neurological abnormalities were seizures beginning at 1 year of age, microcephaly, and inability to hold his head up. His cardiovascular and pulmonary evaluations were unremarkable. Methemoglobin level by spectral absorption pattern was 18 per cent. A qualitative enzymatic assay confirmed the deficiency of the cytochrome b5 reductase enzyme. With this definite diagnosis, a prenatal diagnosis for the next child of this couple will be possible.

Randomized, single-blind comparison of the immunogenicity and reactogenicity of 20 micrograms and 10 micrograms doses of hepatitis B vaccine in adolescents.

The study compares the effect of two different doses of a recombinant DNA hepatitis B vaccine (Engerix-B) administered to 320 healthy adolescents divided randomly into two equal groups, using the 0, 1 and 6 month's vaccination schedule. Initially the larger dose elicited protective levels of antibody in a greater proportion of subjects. The seroprotection rates were significantly higher at both months 1 (17.6% v/s 9.2%) and 2 (68.8% v/s 56.7%). The difference was especially relevant 6 months after the start of the vaccination schedule when a 92.4% seroprotection rate was obtained in the 20 micrograms dose group, whereas only 78.3% of subjects in the 10 micrograms dose group had protective antibody levels. Furthermore there were significant differences in anti-HBs geometric mean titers for seroconverters at months 6 (109 v/s 56mlU/ml) and 7 (4774 v/s 2705mlU/ml). However one month after the third vaccine administration, both doses produced similar high seroprotection rates (97.9% and 97.1%, respectively). The difference in the generally mild overall reactogenicity for the 2 dose levels was not remarkable although the higher dose produced more local symptoms. The conclusion from the study was that the 10 micrograms dose produces a very good antibody response in adolescents, provided the full vaccination course of three doses, according to a 0, 1 and 6 month's schedule, is administered. However, the 20 micrograms dose should be used if compliance to the full course is in doubt since a 92.4% seroprotection rate can be obtained with 2 injections compared to only 78.3% with the 10 micrograms dose.

Hepatitis A antibody in secondary school children in Bangkok.

There are very few published reports on the prevalence of hepatitis A virus in Thailand. This paper is to report the prevalence of the antibody to hepatitis A virus (anti HAV) in secondary school children of different age groups in Bangkok. One hundred seventy two serum specimens from students (age 10-19 years, from M1-M6) were tested for anti HAV by ELISA. The antibodies were detected in 25, 27.3, 31, 30 and 50 percent of children who were in the age groups of 10-11, 12-13, 14-15, 16-17 and 18-19 years respectively. Children with positive anti HAV had histories of jaundice or liver disease more than children without anti HAV. (p < 0.05) The members of the families in both groups (with and without anti HAV) were not significantly different (6.8 + 3.2 vs 7.0 + 2.9) According to our data, two-thirds of secondary school children had no immunity to hepatitis A virus. When hepatitis A vaccine is available, these subjects may be considered a target population for vaccination for disease control.