Observations on little known diseases of camels (Camelus dromedarius) in the Horn of Africa.

The camel is a comparatively hardy animal and is less susceptible to many of the diseases that affect other livestock species in the same areas. Despite that, the camel may contract many other diseases, some of which are still unknown. Pastoralists have for centuries herded camels in the arid and semi-arid areas of Kenya, and elsewhere in the Horn of Africa, and they have encountered and named many new diseases. However, the exact causes of many of these illnesses, such as Lahaw-Gaal, Firaanfir, Laaba, Jajabsa and Yudleye remain unknown. This paper presents the observations of pastoralists on some of the diseases which have been found among camels in northern Kenya. These observations offer intriguing clues to modern veterinarians who are trying to establish and characterise the aetiology of the diseases and ultimately find effective treatments. The authors also provide examples of ethno-veterinary knowledge and practices that could be useful for the development of animal health and production in Africa.

DNA fingerprinting of Trypanosoma vivax isolates rapidly identifies intraspecific relationships.

Using the polymerase chain reaction and arbitrarily selected oligonucleotide primers of 10 or 11 bases, we have amplified DNA sequences from Trypanosoma vivax parasites isolated from South America and Africa. On the basis of polymorphisms in the DNA fingerprints generated by three of the primers, the parasites could be separated into two major groups, one comprising T. vivax isolates from Kenya and the second including all the other T. vivax parasites (from Colombia, The Gambia, Nigeria and Uganda). One of these three primers (ILo 525) also gave isolate-specific DNA fingerprints for the parasites tested, which will allow the use of this technique both in the species identification and discrimination of T. vivax parasites.

Comparative studies of Trypanosoma (Duttonella) vivax isolates from Colombia.

The characterization of four Trypanosoma vivax isolates from Colombia in South America showed that although minor phenotypic differences existed between them, these parasites are antigenically related and belong to a single serodeme. Characterization by isoenzyme assay, karyotyping and DNA probe analysis, showed the Colombian isolates to be more similar to the West African than to Kenyan T. vivax. There was, however, little serological cross-reactivity between South American and African groups of T. vivax. Although the T. vivax isolates from Colombia were pathogenic for dairy calves which showed the typical sign of progressive emaciation, these parasites failed to infect mice or tsetse and could not be cultivated as bloodstream forms in vitro. This study represents initial attempts to establish the phenotypic and serological diversity amongst T. vivax isolates from South America.

Comparison of Trypanosoma grayi-like isolates from west and east Africa.

Three flagellates recently isolated from the hindguts of tsetse flies in West Africa were compared with a previously described T. grayi-like trypanosome isolated in East Africa. In media with Microtus agrestis feeder layer cells, the flagellates developed into bloodstream-like trypomastigotes, which resembled the description of T. grayi from the blood of crocodiles. The results of isoenzyme electrophoresis suggest that the isolates are T. grayi-like trypanosomes, and that some variation exists between the West and East African stocks of these reptile trypanosomes.

Avian trypanosomes in Simulium and sparrowhawks (Accipiter nisus).

Isolates of avian trypanosomes from nestling sparrowhawks (Accipiter nisus) and from Simulium latipes were compared by isoenzyme electrophoresis with the previously described avian trypanosomes Trypanosoma corvi and T. everetti. Simulium isolates developed into trypomastigotes in semi-defined medium at 37 degrees C confirming that they belong to the genus Trypanosoma. Cellulose acetate electrophoresis (CAE) and polyacrylamide gel electrophoresis (PAGE) methods were employed. A total of 11 enzymes was examined, of which 8 gave satisfactory results for all lysates (MDH, ICD, PGM, 6PGD, SOD, PEP I, PEP II and PEP D). The zymograms of 3 isolates from Simulium and 4 from A. nisus were similar indicating that they were the same organism and the isoenzyme patterns coincided with those of T. corvi. It is concluded that A. nisus and S. latipes are infected with T. corvi. Flagellate infections were found in the midgut, hindgut and rectum of Simulium where large numbers of epimastigotes were found in the lumen and attached to the cuticular intima of the rectal ampullae by hemidesmosomes at the distal end of an expanded flagellum. Out of 285 nestling sparrowhawks 13 (5%) were infected with trypanosomes. In view of their age and inability to preen themselves it is suggested they became infected via infected prey.

Comparative studies on Megatrypanum trypanosomes from cervids.

Trypanosomes were isolated by culture from 2 out of 50 blood samples collected from reindeer (Rangifer tarandus L.) in northern Sweden and from a blood sample from a moose (Alces alces) from Southern Sweden. The parasites were indistinguishable morphologically from other trypanosomes reported from cervids, both as epimastigotes in axenic culture at 27 degrees C and as bloodstream-like trypomastigotes cultured on mammalian fibroblasts at 37 degrees C. Surface carbohydrate and isoenzyme comparison of these isolates with four American isolates, from reindeer (Rangifer tarandus), mule deer (Odocoileus hemionus), moose (Alces alces) and elk (Cervus canadensis), are reported. The isoenzyme patterns of the isolate from the Swedish moose were similar to those of the isolates from America while the patterns of the 2 isolates from the Swedish reindeer were considerably different from the others; these 2 isolates may represent a new species. Lectins can be used to distinguish between the trypanosomes of cervids.

Zymogram and life-history studies on trypanosomes of the subgenus Megatrypanum.

Of 13 Swedish dairy cows examined, 12 (92.3%) were found to be infected with trypanosomes by cultivation of blood samples. Of the two species of tabanid fly caught close to the cattle, 33.3% of the Tabanus bromius and 8.6% of the Haematopota pluvialis were also found to be infected with trypanosomes on dissection. Isoenzyme patterns of trypanosome isolates from one H. pluvialis and from six cattle were identical, incriminating this fly species as a vector of the trypanosome. Comparison of these isolates with other Megatrypanum isolates indicated that the Swedish parasites were a form of Trypanosoma theileri and that T. theileri and the badger parasite T. pestanai are closely related. An isolate of a Megatrypanum from a buffalo (Syncerus caffer) in Kenya was entirely different from T. theileri.

Camel trypanosomiasis and its vectors in Somalia.

Blood samples from 3000 Somali camels (Camelus dromedarius) were examined for trypanosome infection. Of these, 160 (5.33%) were infected with Trypanosoma evansi, one (0.03%) with T. congolense and one (0.03%) with T. brucei. Camel trypanosomiasis occurred in most areas of tabanid infestation throughout the country. The tabanids Philoliche zonata and P. magretti are incriminated as the major vectors of the disease.

Chitin derivatives as novel substrates for Trypanosoma brucei brucei attachment in vitro.

Procyclic trypomastigotes of Trypanosoma brucei brucei, cultured in Cunningham's medium with 20% heat-inactivated foetal calf serum at 27 degrees C, attached to chitosan and to gels of N-acetyl chitosan and glycol chitosan. Following attachment, epimastigotes, metacyclic-like trypomastigotes and multinucleate parasites appeared in the culture supernatant.

Morphological changes of Trypanosoma vivax in mice.

Morphological changes were observed in the blood forms of Trypanosoma vivax strain Y486 in mice on Days 12-13 of infection, following the peak parasitaemia. During this period elongate trypomastigotes, 25-40 micron long, were observed, most showing an anterior movement of the kinetoplast towards the nucleus and some having a blunt posterior end. In a few parasites a complete transformation to the epimastigote form, 40-42 micron long, was observed. Small sphaeromastigotes were also present, especially in the fine capillaries of various organs. Smears and electron microscopy suggested the presence of extra-vascular forms in the spleen.