[Epidemic of Rift Valley fever in the Islamic republic of Mauritania. Geographic and ecological data]. / Epidémie de fièvre de la Vallée du Rift en République islamique de Mauritanie. Données géographiques et écologiques.

During and after the Rift Valley Fever epidemic in southern mauritania, we conducted epidemiological inquiries in order to determine epidemic and epizootic areas. The epidemic area was divided into two different zones. The first was located along the right bank of the Senegal River, around the town of Rosso. The second was located near the town of Kaedi. This epidemic area was included within the epizootic area, which stretched to the south, between Rosso and Saint-Louis. Several ecological changes had occurred in the recent past including erection of dams on the Senegal River for irrigation, and heavier rainfall than during previous years.

[Evaluation of indicators of health in the area of Trarza during the epidemic of Rift Valley fever in 1987]. / Evaluation des indicateurs de santé dans la région du Trarza lors de l'épidémie de fièvre de la Vallée du Rift en 1987.

Randomized epidemiological studies conducted inside the Rift Valley fever epidemic area permitted an estimate of the different epidemiological rates. For the town of Rosso, the total number of infected persons was estimated at 9,320, the total number of symptomatic diseases at 1,013 and the number of deaths at 47. The minimal number of deaths for the area which had access to the hospital was 232. The immunity rate in the town was 34.89% after the epidemic. The ELISA test was used to test human and animal IgG and IgM antibodies. Human samples were collected using the "confetti" technique. After the epizootic the incidence was 36.9% and the immunity was 70.06% for animals sampled in the town.

Rift Valley fever among domestic animals in the recent West African outbreak.

Severe haemorrhagic disease among the human population of the Senegal River Basin brought the Rift Valley fever virus (RVFV) outbreak of 1987 to the attention of science. As in previous RVFV outbreaks, local herdsmen reported a high incidence of abortion and disease in their livestock. Serum samples were obtained from domestic animal populations from areas near Rosso, the best studied focus of human infection, as well as other areas distant from known human disease. Among animals from the area of high incidence of human disease, antibody prevalence was as high as 85%, with approximately 80% of the sera positive for both RVFV IgG- and viral-specific IgM antibodies. In contrast, human populations in the same area had lower RVFV antibody prevalences, 40% or less, with 90% also being IgM-positive. Sera from livestock in coastal areas 280 km south of the epidemic area were negative for RVFV antibodies. Thus, the detection of RVFV specific IgG and IgM antibodies provided evidence of recent disease activity without the requirement to establish pre-disease antibody levels in populations or individuals and without viral isolation. Subsequently, detection of modest levels of IgG and IgM in the Ferlo region, 130 km south of the Senegal River flood plain, established that RVFV transmission also occurred in another area of the basin. Similar serological testing of domestic ungulates in The Gambia, 340 km south of Rosso, demonstrated antibody prevalence consistent with a lower level of recent transmission of RVFV, i.e., 24% IgG-positive with 6% of the positive sera also having RVFV-specific IgM.