The value of methemoglobin reduction test as a screening test for neonatal glucose 6-phosphate dehydrogenase deficiency.

Glucose 6-phosphate dehydrogenase (G-6-PD) deficiency is common in the Thai population and is the cause of neonatal hyperbilirubinemia and hemolytic anemia. This X-linked disorder is much more common in males than females. The objectives of this study were to compare the result of the screening methemoglobin reduction test (MRT) with the gold standard G-6-PD activity, and also to determine the prevalence of G-6-PD deficiency in the cord blood and blood of neonates with hyperbilirubinemia. Five hunderd and twenty two randomly selected cord blood (350 males, 172 females) and 229 peripheral blood from neonates with hyperbilirubinemia were assayed for G-6-PD enzyme activity using a WHO-recommended standard test as well as methemoglobin reduction (MR) test. The results showed that prevalence of G-6-PD deficiency from the cord blood was 11.1 per cent in males, and 5.59 per cent in females. Among newborns with neonatal jaundice, the prevalence of G-6-PD deficiency was 22.1 per cent in males and 10.1 per cent in females. MRT in cord blood G-6-PD deficiency screening had acceptable sensitivity (85.7%) and high specificity (98.1%). The sensitivity of MRT in jaundiced infants was low (60.0%) whereas the specificity was acceptable (92.1%). The negative predictive values were more than 90 per cent while the positive predictive values were low (61-65%) from both specimens. Conclusions: G-6-PD deficiency is common in the Thai population, both in males and females and can be screened from cord blood by using low cost MRT. G-6-PD deficiency contributes to 20 per cent of neonatal jaundice, and screening with MRT yields low sensitivity.

Comparison study of combined DTPw-HB vaccines and separate administration of DTPw and HB vaccines in Thai children.

The safety, immunogenicity and tolerability of two different DTPw-HBV combination vaccines, containing 5 and 10 microg of HBsAg; were investigated in comparison with separate administration of DTPw and HBV (10 microg of HBsAg). A three dose primary vaccination course at 2, 4 and 6 months of age was followed by a booster dose at 18 months. All vaccines were safe and well tolerated. The DTPw-HBV combination vaccine containing 10 microg of HBsAg elicited significantly higher anti-HBs titres than the other two vaccines after the primary and booster vaccination course. All vaccines elicited a high response against the other components. Based on these results, DTPw-HBV (10 microg HBsAg) was the most effective vaccine at this schedule.

Immunogenicity of hepatitis B vaccine in premature infants.

The immunogenicity of plasma-derived hepatitis B vaccine was studied in 39 premature neonates, whose weights were 1,800-2,400 g and gestational ages 32-37 weeks. All maternal antiHBc antibody were negative. Dosage of 5 micrograms of hepatitis B vaccine (Pasteur vaccine) was given at 0, 1, 2 and 12 months after birth. At the ages of 1, 2, 4, 9, 12 and 13 months, antiHBs antibody was found in 7.7%, 20%, 69.7%, 81.4%, 77.3% and 89.5%, respectively, while the geometric mean titer in this seropositive group, starting at age 2 months was 37, 121, 113, 69 and 1,016 mIU/ml. There was no severe reaction attributed to the vaccination. The result indicated that the vaccine was immunogenic. Although the conversion rate was low after primary injection, a satisfactory response developed at age 4 months after 3 doses of vaccine.