[Anti-Haemophilus influenzae b (Hib) natural immunity in children in Burkina Faso].

BACKGROUND

Natural immunity to Haemophilus infection type b that is acquired by the mothers and passively transmitted to their newborns is not well-known in developing countries, where the frequency of Haemophilus meningitis in infancy is high.

POPULATION AND METHODS

Blood samples (5 ml) were taken from 89 women at the time of delivery and from the cord of their babies. Blood samples were also taken from 290 infants and children, distributed into nine subgroups as a function of their age. Children with protein-calorie malnutrition and immune deficiency were excluded from the study. Antibodies against Haemophilus influenzae were measured by Elisa and radioimmunologic methods. Blood concentrations of 0.15 pg/ml or more were considered to be protective.

RESULTS

All the blood samples of mothers and cords contained protective levels of antibodies, as did the samples from 30% of those infants aged 0-60 days (all the infants were less than 1 month). No infant in the subgroup 12-23 months had protective levels of antibodies. The incidence of Haemophilus meningitis was correlated with the absence of antibodies.

CONCLUSION

Maternal immunity is gradually lost by babies during their first 2 months of life, earlier than in developed countries. Early vaccination, at 3 months of age, is mandatory.