Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. I. Studies with human sera from Ghana collected eight years after the first outbreak

Abstract

In 1969 and early 1970, during the pre-epidemic period of acute hemorrhagic conjunctivitis (AHC) in the upper north regions of Ghana, 191 human sera were collected. In 1977, eight years after the first epidemic of AHC in Ghana, 1008 human sera were also collected in various regions of Ghana. These sera were examined for virus neutralizing (VN) antibody against the J670/71 strain of enterovirus type 70 (EV70). In the pre-epidemic 1969-1970 sera, a low prevalence rate (6%) of VN antibody, with a titer of greater than or equal to 1:8, was found; the geometric mean titer (GMT) was also very low (1:1.85). In the post-epidemic 1977 sera, a high prevalence rate (53%) of VN antibody was found in the Ghanaian population, and the calculated GMT was also high (1:7.36). A higher antibody prevalence was detected in coastal (Accra: prevalence rate of 58% and GMT of (1:7.84), forest (Kumasi: 58% and GMT 1:7.52) and peri-forest (Tamale: 51% and GMT 1:7.46) areas than in the tropical savanna area (Bolgatanga: 41% and GMT 1:5.13). The demonstration of VN antibody in children under seven years of age showed that EV70 was still widely distributed and highly active in Ghana. The VN antibody found in human sera was predominantly IgG.