Aerosol infection of rhesus macaques with Junin virus

The purpose of our work was to determine if aerosols of Junin virus can infect rhesus macaques and if the disease is the same as that produced by virus inoculated parenterally. The 6 macaques exposed to the virus by aerosol became acutely ill during the 3rd week after exposure, and all died. Three died by day 21, while the remainder died after 1 month. Junin virus was found primarily in visceral organs of those animals dying before 21 days after infection and in the central nervous system tissues from animals dying later. Histological changes were similar to those reported in rhesus monkeys after parenteral Junin viral infection. Gastrointestinal necrosis, however, was less severe in aerosol-infected animals and the associated septicemia was not seen. High levels of alpha interferon were detected by the 3rd day in all infected macaques. Experimental Argentine hemorrhagic fever induced by aerosol infection in rhesus macaques was similar to that seen after parenteral challenge and mimicked closely the clinical syndrome observed in humans.

Filter paper confetti in a serological Rift Valley fever survey

In order to collect epidemiological data about the Rift Valley fever epidemic in Mauritania, we decided to use the filter paper method. The mean recovery level of specific antibodies from filter paper, tested using an immunoenzymatic method, is around one fourth. Taking the mean haematocrit into account, we estimated the extract square with a 1/300 dilution. This method was very useful for epidemiological studies, we observed few patient refusals, but it is necessary to know the exact specificity of the antibodies.

Isolation of the Rift Valley fever virus by inoculation into Aedes pseudoscutellaris cells: comparison with other diagnostic methods

The Rift Valley fever epidemic, which arose in the south of Mauritania beginning on October 15, 1987, enabled a comparative study of different diagnostic methods among humans. During the first two weeks of the epidemic, four parallel methods were used: inoculation into Aedes pseudoscutellaris cells, inoculation intracerebrally into suckling mice, tests by immunocapture of the circulating antigen and detection of type IgM gammaglobulins. Of 370 examined sera, 181 showed at least one marker of recent infection. Inoculation into A. pseudoscutellaris cells was by far the most sensitive and easiest method to use. Detection of the antigen by immunocapture was also a useful technique, since it allowed quick aetiological diagnosis or examination of sera conserved under poor conditions. However, its sensitivity was weak, as it could only detect 26% of positive cases. Vero cells used on a limited scale, in this particular case seemed less sensitive than A. pseudoscutellaris cells. Of a total of 991 sera, 221 diagnoses were reported by discovery of the virus and 271 by detection of specific IgM. In every case, A. pseudoscutellaris cells seemed most appropriate as the system of reference.

Rapid diagnosis of Rift Valley fever: a comparison of methods for the direct detection of viral antigen in human sera

Human sera collected during the 1987 Rift Valley fever (RVF) epidemic in the Senegal River basin were analysed using three enzyme immunoassays to establish the best method for rapid diagnosis of RVF. A biotin-avidin-enhanced antigen detection method utilizing monoclonal antibodies proved most sensitive. Eighty-two viremic human sera were tested, and this assay detected antigen in 29.3% of the samples.