Diseases of plants transmissible between plants and man (phytonoses) exist.

Since zoonoses (singular zoonosis) are infections or infectious diseases of animals transmissible to man, or occasionally from man to other animal species, it is logical that should any diseases of plants be found that are transmissible between plants and man they should be termed phytonoses (singular phytonosis). The genome of human uveitis mycoplasma-like organisms (MLO) has been reported to be showing a very high homology to plant MLO. For this reason, and because there are several other known similarities between plant and human MLO, it is hypothesized that at least one class of phytonoses, namely cross-infection of MLO between plants and man, exists. There are, however, other possibilities. Cross-infection transmission experiments, the results of which could add credibility to the hypothesis, could be undertaken.

The morphology of human immunodeficiency virus particles by negative staining electron microscopy.

Negative staining electron microscopy was used to examine culture fluids from the H9/HTLV-III cell line after concentration by centrifugation. Characteristic retrovirus-like particles bearing distinctive envelope projections were seen. The virion envelope was frequently extended in the form of a bleb or a tail. These particles were morphologically virtually indistinguishable from similar preparations of Friend murine leukaemia virus. H9/HTLV-III culture fluids contained, in addition, numerous comet-shaped particles with a dense head and flared tail. These particles were clumped by the addition of anti-HTLV-III-positive serum suggesting that they may represent intermediate forms of the virus.

Arthropod-borne virus zoonosis surveillance in the Cape Province: 1. Prospective serological investigations for virus activity in the Beaufort West and Middelburg Districts during 1981.

In addition to the routine sero-epidemiological surveillance for arthropod-borne viral zoonoses in the Cape Province carried out by the Department of Medical Microbiology and State Health Department of Virology laboratory, we conducted a prospective serological investigation for virus activity during 1981 in two districts of the Province, namely the Beaufort West and Middelburg districts, which experienced heavy rainfall during the first two months of that year. The approach used was to obtain paired serum samples from identified domestic stock representative of several species from 2-5 months apart and to test them for haemagglutination inhibition antibodies to Rift Valley fever, Wesselsbron and Middelburg virus antigen preparations in order to ascertain, as an indication of viral activity, whether changes in antibody levels occurred between the collection dates. The results indicated that there was probable activity of Rift Valley fever virus and activity of Wesselsbron virus (or related flaviviruses) and Middelburg virus (or related alphaviruses) in the Karoo between the middle of February and the end of July 1981. Despite this activity and heavy rainfall registered at meteorological stations in both the Beaufort West and Middelburg districts as well as general reports of heavy rainfall and considerable mosquito activity over widespread areas of the Karoo, Eastern and S.W. Cape Province, there were no epizootics or epidemics of overt arthropod-borne zoonotic viral disease in the province during 1981.

Lymphosarcoma in a cat.

Feline leukaemia virus (FeLV) antigen was detected in a cat from Cape Town which was subjected to euthanasia after a long history of upper respiratory infection and progressive emaciation. Based on the necropsy findings and subsequent histopathological examinations, a diagnosis of lymphosarcoma was made. It is regarded as likely that this tumour was caused by infection with FeLV.