ANTIBODY-RESPONSE TO POLYRIBOSYL-RIBITOL PHOSPHATE ANTIGEN OF HAEMOPHILUS-INFLUENZAE IN ECUADORIAN AND GERMAN CHILDREN

Serum samples from 1,221 Ecuadorian children 0 to 5 years of age and f rom 236 German subjects were tested by enzyme-linked immunosorbent ass ay for class-specific antibodies to the capsular polysaccharide of Hae mophilus influenzae type b (PRP antigen). A gradual prevalence increas e of and mean titer increase in immunoglobulin M (IgM) antibody was se en in Ecuadorian but not in German children older than 6 months. At th e end of the first year of life, about 50% of the Ecuadorian children showed IgM and IgG antibody to PRP. Seroepidemiological analysis revea led that living at a low altitude and lower calorie intake (a proxy me asure of breast-feeding) were factors associated with earlier acquisit ion of PRP antibody. Children from low-altitude areas of Ecuador also experienced significantly more episodes of significant respiratory inf ections. The acquisition of PRP-reactive antibodies in Ecuadorian chil dren might thus reflect exposure to encapsulated H. influenzae type b in lower respiratory tract infections.