A case of haemorhagic fever caused by Crimean-Congo haemorrhagic fever (CCHF) virus in May, 1983, in a patient who lived in Selibaby south-eastern Mauritanla, prompted an epidemiological survey in this area in March, 1984. This area around Selibaby is indifferenciated dry savannah it is an important cattle raising area, specially during the dry season when herds migrate from the north of Mauritania. During 1982 and 1983, the migration was intensified by the drought. The patient owned a large herd of camels about 20 km from Selibaby and was staying with the herd when he fell iII.
We collected ticks from camels, cattle, sheep, goats, and horses, blood sanples from cattle, rodents, and humans, and organ pools from rodents and cattle. In and around the Selibaby area, including Bakel region of Senegal which les along the border CCHF Bakel region of Senegal which les along the border. Isolation from ticks is summarized in the table.
CCHF Virus strains were identified by complement fixation test with mouse immune ascitic fluid to the reference lb Ar 10200 strain virus. One of the strains isolated, ArD 38554, was compared by neutralisatlon test with the reference strain to provide definitive identification of the virus. Identical homologous and heterologous log 10 neutralizing antibodies of 5.5 and 5.0 were obtained in tests in mice.
From 716 Hyalomma marginatum rufipes ticks collected from camels, 5 strains of CCHF virus were isolated whereas none were isolated from 620 H dromedarii collecteded trom fhe same camel.
A serologlcal survey by indirect immunofluorescence antibodody (IFA) assay with strain CCHF Ib Ar 10200 gave positive reaction rate of 32% (8/25) for cattle: and, for rodents, 16% for Arvicanthis niloticus (7/43), 27% for Mastomys erythroleucus (3/11), and zero (O/2) or Taterillus pygarguss and/or gracilis. Of 59 human sera tested 1 was positive.
From hospilal records in Selibaby relating to haemorrhagic fever in this area we found two cases of haemorrhagic fever clinicaly compatible with CCHF which occurred in 1982 among stock breeders.
A serological survey was also done with Rlft Valley fever (RVF) virus by IFA usIng strain Ar B 1976-Zinga. 9 of 26 (35%) cattle breeders had antibodies, with titres ranging from 16 to 128 in contrast, no antibody was found in 7 sera of butchers or in 26 sera from residents of this area who were not connected with camel antibodies were also present in 2/25 cattle, but 0/56 rodent sera had IFA antibody to RVF virus. The human sera were also treated for IgM antibody capture ELISA with an inactivated RVF antigen 2 sera were positive (titres 200 and 16OO), indicating recent infection RVF virus was not isolated from ticks or from rodent and cattle organ pools.
These results suggest that in the Selibaby area, CCHF virus is enzootic. The incidence of CCHF in man seems low but cases have been reported.
Investigations are needed to determine the distribution of CCHF virus in Mauritania and its relation to haemorrhaglc. syndromes in man, the role played by camels in the spread of CCHF virus in northern Mauritania during the rainy season and during migrations; the dlfferences between H. marginatum rufipes and H. dromedarii in their tendency to be infected by and to transmit CCHF virus, the significance of rodents in maintaining CCHF virus circulation in the Selibaby area; and the relation between Rift Valley fever and camels in Mauritania.