Adults acquire filarial infection more rapidly than children: a study in Indonesian transmigrants

To dissociate the influence of host age from length of exposure on acquisit ion of filarial infection, we examined the development of microfilaraemia a nd anti-filarial IgG4 in all ages of a naive population that became suddenl y exposed to Brugia malayi as a result of transmigration. Responses in 247 transmigrants, who had settled for periods of several months up to 6 years in their ne homesteads, were compared with those of 133 life-long residents . As shown in earlier studies, anti-filarial IgG4 increased with age in the indigenous population, whose age is equivalent to length of exposure. Howe ver. by examining transmigrants, it became clear that development of specif ic IgG4 was influenced by age, since levels of this antibody were consisten tly higher in transmigrant adults than in transmigrant children, despite an equal length of exposure to filarial infection. Examining microfilaraemia, it was confirmed that infection establishes more rapidly in adults than in children.