Serology and carriage of Pseudomonas pseudomallei: a prospective study in 1000 hospitalized children in northeast Thailand

Throat swabcultures and indirect hemagglutination assay (IHA) for Pseudomonas pseudomal-lei were done in 1000 randomly selected children at a large hospital in northeast Thailand. During 18 months, 17 children with melioidosis were admitted (0.46 % of pediatric admissions excluding neonates born ' in the hospital). Throat swab was positive for P. pseudomallei in 8 of these but in none of 1000 control children. IHA seroprevalence rose at a conversion rate of 24% per year, from 12 % in those 1-6 months old to a plateau at--80 % after age 4 years. No control child <4 had an IHA titer> 1:160. The median titer in children with melioidosis was 1:80 (range, negative [in3]-1:5120). Specificity of IHA declined with age, but high titers (~1:640) remained diagnostically useful.Thus, throat carriage of P.pseudomallei indicates active melioidosis. There is no evidence for an asymptomatic carrier state in children. Environmental exposure to P. pseudomallei in endemic areas begins when the child becomes mobile. Melioidosis is an important cause ofmorbidity and mortal-ity in the rural communities of Southeast Asia [1, 2]. Al-though Pseudomonas pseudomallei is predominantly a cause of disease in adults with underlying diseases, such as rena