Trypanosoma congolense. 3. Serological responses of experimentally infected cattle.
Abstract A complement fixation (CF) test for the diagnosis of Trypanosome congolense infection in cattle was developed and compared with the indirect fluorescent antibody (IFA) test. Serological investigations were made with cattle immunized with irradiated T. congolense and challenged with untreated T. congolense. Trypanosomal antibodies were demonstrated by the CF test. The results indicated good specificity and sensitivity between the CF method and the IFA test. The CF test also afforded easier reading of results than the IFA test; however, antigen preparation was more difficult in the former. The serological responses detected by the IFA and CF test appeared to be influenced by early variations of parasitemia, although no correlation appeared to exist between titer and parasitemia at later stages of the infection. Antibodies were detected in animals which received injections of irradiated T. congolense prior to challenge with viable organisms.
Features of Epidemiological Importance in the Development of Cyclically Transmitted Stocks of Trypanosoma Congolense in Vertebrate Hosts
The epidemiological importance of differences in transmissibility, infectivity, antigenicity, pathogenicity and drug sensitivity among species and strains of the African pathogenic trypanosomes is well known. These aspects of trypanosomiasis have been studied particularly intensively in the case of Trypanosoma brucei, but less attention has been given to T. congolense and T. vivax, the two most serious trypanosomal pathogens of domestic livestock. Our recent studies have included experiments involving the cyclical transmission by Glossina morsitans of stocks of T. congolense from locations in East and West Africa to rabbits, calves and sheep, and examinations of formation of local skin reactions and the antigenicity of the trypanosomes developing in these hosts. Differences have been observed in the occurrence of local skin reactions in different host species, and antigenic differences have been found between trypanosome stocks from different areas by serological tests and immunisation and challenge experiments. Differences in the serological responses of rabbits to different trypanosome stocks have also been observed during estimations of antibody levels using enzyme-linked immunosorbent assays.
Do Potential People Have Moral Rights?
By a potential person I shall mean an entity which is not now a person but which is capable of developing into a person, given certain biologically and/or technologically possible conditions. This is admittedly a narrower sense than some would attach to the term ‘potential'. After all, people of the twenty-fifth century, if such there will be, are in some sense potential people now, even though the specific biological entities from which they will develop, i.e. the particular gametes or concepti, do not yet exist. For there do exist, in the reproductive capacities of people now living and in the earth's resources, conditions adequate to produce these future people eventually, provided of course that various possible catastrophes are avoided. Indeed, in some sense of ‘potential’ there have been countless billions of potential people from the beginning of time. But I am concerned not with such remote potentialities but with currently existing entities that are capable of developing into people.