Cell-mediated and humoral immune responses to BCG and rubella vaccinations and to recall antigens in onchocerciasis patients.

In seven Liberian villages of different endemicity for onchocerciasis 629 persons were tested for tuberculin reactions using 5 i.u. purified protein derivative or old tuberculin. No correlation between infection with Onchocerca volvulus and reactivity to tuberculin was detected on a community level, but a direct comparison of results of infected and non-infected individuals in two neighboring villages revealed a lower responsiveness in persons with onchocerciasis. The conversion rate three months after BCG vaccination was significantly lower in children with onchocerciasis (48%) than in controls (85%). The possible impact of this finding on the efficacy of BCG vaccinations is discussed. Girls aged 2-16 years were screened for rubella antibodies using a latex agglutination test. Sera from 74 girls, who showed no antibodies, were examined before and four months after rubella vaccination by haemagglutination-inhibition-test and haemolysis-in-gel-test. No difference in the humoral immune response of girls with or without onchocerciasis was found. Seroconversion rates were 98% and 100%. Delayed cutaneous hypersensitivity (DCH) to seven ubiquitous recall antigens was tested in 147 persons infected with O. volvulus and compared to the results of 142 non-infected controls. A reduced responsiveness was seen in persons with onchocerciasis, the difference being greatest in young children 2-7 years of age. In connection with the results of tetanus vaccinations reported earlier, these findings verify the existence of a reduced in vivo responsiveness of cell-mediated immunity to non-specific antigens in onchocerciasis in the rain forest of West Africa. Humoral immune responses however appeared to be unaffected.