A serological survey has been made on 5,553 serums selected in the central and western areas of Centrafrican Republic.
The following antigens have been used:
Group A: Chikungunya, O'Nyong-Nyong, Sindbis
Group B: French Neutropic Strain of Yellow Fever, Uganda S, West Nile, Zika
Group Bunyamwera : Bunyamwera.
Four areas showing different features can be put designed as follows:
-The forest area where positive reactions to the arbovirus of groups A and B ar not numerous.
-The savannah forest border-line which mark the south limit of Chikungunya -O'nyong nyong epidemic. The virus incidence of group B is weak but west Nile and Zika can be found.
- The arboreous savanna area where the artibodies to group A: Chikungunya-Onyong nyong are found in a large proportion of the population. The virus is always in circulation, several serological conversions have been recenly observed.
The activity of the group B viruses is weak but the presence of the isolated Yellow Fever antibodies among unvaccinated children confirm the presence of sylvan virus.
Concerning the antibodies Chikungunya-O'Nvong-Nyong the banks of Oubangui present the characteristics of the traversed area : weak incidence in forest, more important in savanna. The group B viruses have a rather weak infuence but West Nile, Zika and UGS are found. This area is the only one where Sindbis exists.
In the four areas Bunyamvera Group arboviruses have a weak incidence.