Survey for antibodies against arthropod-borne viruses in the sera of indigenous residents of Angola

Abstract

Sera collected in 1960 from 492 indigenous residents of 14 widely scattered localities in Angola were tested for HI antibodies against 18 viruses: 5 from Group A, 9 from Group B, 1 from Group C, 2 from the Bunyamwera Group, and Rift Valley fever virus. Results of these tests indicated that the prevalence of antibodies was greatest in the 6 localities sampled in the north-western coastal and plateau region. Sera positive in the HI test were further tested with the respective viruses by mouse neutralization test. Analysis of these results according to sera positive for only one virus of Group A, B or Bunyamwera indicated that Sindbis, chikungunya, Semliki Forest, Wesselsbron, Zika, H 336, West Nile, Bunyamwera and Germiston viruses have been active, predominantly in the north-western region, and that Spondweni virus has been present. There was no evidence that Mayaro or Middelburg virus has infected the population sampled, or that Ntaya, dengue 1 or dengue 2 virus has been present. In 3 localities in the north-west interpretation of results with Group B viruses was complicated by the fact that some of the donors had been vaccinated against yellow fever. HI test results with Oriboca virus suggest that this or a closely related member of Group C exists in Angola. In additional neutralization tests, one or more sera from children and adults in each of the 6 north-western localities protected against Lumbo (California complex), Pongola or Bwamba fever virus.