| the 1970 yellow fever epidemic in okwoga district, benue plateau state, nigeria. 3. serological responses in persons with and without pre-existing heterologous group b immunity. | serological studies of persons infected with yellow fever (yf) during the 1970 epidemic in okwoga district, nigeria, indicated that epidemic yf occurred despite a high prevalence of pre-existing group b arbovirus immunity, which increased with age. the viruses involved were primarily dengue, zika, and wesselsbron. patterns of responses of haemagglutination-inhibiting, complement-fixing, and neutralizing antibodies in primary yf and in superinfections are defined in this paper. | 1973 | 4546521 |