Isoenzyme comparison of Trypanozoon isolates from two sleeping sickness areas of south-eastern Uganda.

The study characterized 151 Trypanozoon isolates from south-east Uganda by isoenzyme electrophoresis. Stocks were from a range of hosts, including man, cattle, pigs, dogs and Glossina fuscipes fuscipes: 104 isolates were from the Busoga area, 47 were from the Tororo district. Stocks were characterized on thin layer starch gel using eight enzyme systems: ALAT, ASAT, ICD, MDH, ME, NHD, NHI, PGM. Enzyme profiles were generally typical of East Africa; new patterns for ICD and ME were detected. Trypanosomes were classified on the basis of their profile by similarity coefficient analysis and the unweighted pair-group method using arithmetic averages (UPGMA). The majority of trypanosomes were classified in one or other of two genetically distinct groups which corresponded to the strain groups busoga and zambezi, both of which are associated with Rhodesian sleeping sickness in East Africa. Contingency table analyses indicated associations between certain isoenzymes of ICD and PGM, according to host and geographical origin. Significant relationships between trypanosome strain group and geographic origin were also demonstrated for some host groups.

Virologic studies on cattle with naturally occurring and experimentally induced malignant catarrhal fever.

Malignant catarrhal fever is an important disease of cattle and certain wild ruminants. It occurs in sporadic and epizootic forms in Colorado cattle. Specimens from 15 cattle with naturally occurring malignant catarrhal fever and 5 cattle with induced disease were examined for cell-free and cell-associated viruses. Enteroviruses were isolated from leukocytes of 2 cattle with field cases of the disease. A herpesvirus with characteristics of the "Movar"-type, isolated from the spleen of another steer with a field case could be propagated optimally in bovine fetal spleen cells. A cell-associated virus, forming polykaryons, was isolated in adrenal and thyroid cells from 3 cattle with experimentally induced malignant catarrhal fever. It was cultured from leukocytes, ependymal tissue, spleen, lymph node, kidney and thyroid and adrenal glands of affected cattle and remained cell-associated in 48 subsequent passages. It was inactivated by freezing and thawing and by treatment with ultrasound; its polykaryon-forming activity was inhibited by 25 mug of 5 fluoro-2' deoxyuridine/ml. This viral agent replicated in bovine fetal adrenal, thyroid, and spleen cells, but not in primary kidney cells or in MDBK, HeLa, or L cells. A representative isolate was identified electronmicroscopically as an enveloped virus, 120 to 150 nm in diameter. Structural analysis indicated that it had properties of the bovine syncytial viruses. Attempts to induce MCF in cattle with 1 of the isolates failed. A parvovirus was isolated from the jejunal lymph node of calf 72-P-293, which had the experimentally induced disease and was also infected with the syncytial virus.

Protective efficacy of isometamidium chloride and diminazene aceturate against natural Trypanosoma brucei, Trypanosoma congolense and Trypanosoma vivax infections in cattle under a suppressed tsetse population in Uganda.

The protective efficacy of isometamidium chloride (ISMM) and diminazene aceturate (DIM) against Trypanosoma brucei, Trypanosoma congolense and Trypanosoma vivax infections in cattle under a suppressed tsetse population was assessed in southeast Uganda. A total of 66 and 57 trypanosome-infected cattle were treated with ISMM and DIM, respectively together with 177 trypanosome-free animals not treated were followed for 12 months, checked every 4 weeks. There was no statistical difference in the mean time to infection with any trypanosome species in animals treated with ISMM or DIM. However, the mean time to trypanosome infection was significantly longer for treated animals than controls. The mean time to infection with each of the three trypanosome species differed significantly, with the average time to T. vivax infection the lowest, followed by T. congolense and then T. brucei. The protective efficacy of DIM was as good as that of ISMM; implying curative treatments against trypanosomosis are sufficient for combination with tsetse control. Isometamidium chloride or DIM had the highest impact on T. brucei and T. congolense infections in cattle.

Sustainability of tsetse control by subsequent treatment of 10% of a previously treated Ugandan cattle population with 1% w/v deltamethrin.

This study was conducted in Masaba and Masafu Sub-counties, Busia District, Uganda to assess the effect on the tsetse fly population of first treating all cattle with 1% w/v deltamethrin pour-on for a few months, followed by treating 10% of the cattle population. Treatment of all cattle for 6 months resulted in a significant reduction in the density of tsetse flies from 6.3 to 0.1 flies/trap/day (FTD), a 98.4% reduction. During the same period, the point prevalence of bovine trypanosomosis dropped from 37.7% to 2.9% (a 92.3% reduction). Treatment was resumed six months later, but this time only 10% of the cattle population received the pour-on treatment at three week intervals for a period of one year. This treatment maintained the tsetse fly density between 0 and 0.5 FTD and the prevalence of bovine trypanosomosis generally remained below 10%. In conclusion, under the local prevailing conditions, treatment of all communally grazed cattle with deltamethrin pour-on effectively suppressed the Glossina fuscipes fuscipes population. However, subsequent treatment of 10% of the cattle probably failed to control the tsetse fly population at a level sufficient to reduce trypanosomosis to acceptable levels.