Kasokero virus: a new human pathogen from bats (Rousettus aegyptiacus) in Uganda.

Two virus strains were isolated by mouse inoculation from blood of Rousettus aegyptiacus fruit-eating bats collected from Kasokero Cave in Uganda. Shortly after these strains were introduced in the laboratory, four additional strains were recovered from laboratory workers who had developed mild to severe illnesses presumably as a result of laboratory infection. Serological studies established that these six isolates are strains of the same virus. Serological tests showed also that this virus is related to Yogue, an unclassified virus.

East Coast fever: cultivation in vitro of cell-free schizonts and merozoites of Theileria parva and their immunogenicity in cattle.

Cell-free schizonts and merozoites of Theileria parva and Theileria lawrencei, derived from parasitized lymphoid cell lines, were propagated in vitro using enriched medium. Use of radioisotopic markers showed that the bovine cell-independent parasites passed through a limited but marked replication by day 4. If normal bovine RBC were inoculated in vitro with the cell-free merozoites, development of piroplasms in the RBC occurred. Electron microscopic studies of the merozoites and piroplasms revealed their structure to be similar to previous descriptions. Cattle inoculated with T parva merozoites and schizonts and later challenge exposed with homologous stabilate developed leukopenia, showed low macroschizont index, and survived longer than unvaccinated controls.

Laboratory studies on the transmission of yellow fever virus by Aedes (Finlaya) notoscriptus (Dipt., Culicidae).

Aedes (Finlaya) notoscriptus (Skuse), a mosquito which occupies a similar ecological niche to Aedes (Stegomyia) aegypti (L), the urban vector of yellow fever virus, was screened as a possible vector of this disease. The results indicate that almost certainly Ae. notoscriptus is refractory to the virus and could not act as a vector if yellow fever were introduced to Australia.

Anaemia in trypanosomiasis: mechanisms of erythrocyte destruction in mice infected with Trypanosoma congolense or T. brucei.

Studies in mice infected with T. brucei or T. congolense showed that increased red cell destruction in the spleen occurred as from the third day of patent parasitaemia and this resulted in a marked reduction of the half-life of transfused syngeneic 51Cr labelled cells. There was a progressive increase in the osmotic fragility of the red cells, especially in T. congolense infected mice which also showed a more severe anaemia. The antiglobulin test was only rarely positive in the late stages of T. brucei infection. Incubation of normal red cells with plasma from infected mice in vitro did not result in haemolysis, but in the case of plasma from T. brucei infected mice, it caused an appreciable reduction in the half-life of the cells when transfused into normal mice. It is suggested that mechanisms of red cell destruction in trypanosome infections are complex and may vary with the species of trypanosomes, the host and the stage of infection.

The specific immunoglobulin response in cattle to Theileria parva (Muguga) infection.

Cattle were inoculated with dilutions of Theileria parva (Muguga) stabilate without concurrent antibiotic treatment. The dilutions were selected to induce severe East Coast fever infections, which in some cases would lead to death. Serum samples were collected and the complement fixation (CF), indirect haemagglutination (IHA) and indirect immunofluorescence (IFA) tests were used to detect T. parva serum antibodies. Sera were fractionated on Sephadex G200 to determine the activities of specific immunoglobulin fractions. Sequential production of IgM antibody followed by 7SIg antibody was demonstrated by the IHA and CF tests. All IFA activity was restricted to the 7SIg fraction. Serologic reactions in the IHA test were detected as early as 4 days after inoculation of the stabilate, CF activity after 8 days and IFA activity after 21 days.