Pathology of the Disease in Sheep Produced Experimentally by Trypanosoma brucei

Abstract

Abstract. Sheep inoculated intravenously with Trypuiiosom bviicei had fever, irregular parasitaeniia, moderate anaemia, subcutaneous oedenia, dullness, anorexia, and nervous signs followed by death in 29-69 days. Emaciation, serous effusions into body cavities and generalised enlargement and oedenia of lymph nodes were seen at necropsy. Microscopically there was extensive localisation of trypanosonies in the extravascular body fluids, and in interstitial connective tissues, resulting in mononuclear inflammatory reactions in the heart, skeletal muscle, skin, brain, pituitary, eye, serosal surfaces, urinary bladder, epididyniis and testis, and in generalised lymphoid hyperplasia. These observations in sheep are comparable to those made in other animals infected with trypanosornes of the brucei group.Trypanosoma brucei, T. congolense, and T. vivax cause the most economically important forms of animal trypanosomiases in Africa. There is relatively little information on the pathogenesis and pathology of the diseases produced by these species in domestic animals [l 11. Infections and diseases causcd in sheep by T. brzxei occur naturally [2, 131, but there is little information on either the prevalence or the pathology. Sheep, however, have been used extensively in the past in investigations of the virulence of various human and animal isolates of trypaiiosonies in the brucei subgroup. Many of these isolates were associated with severe diseases characterized by emaciation, subcutaneous oedema, enlargement of lymph nodes, and corneal opacity [I, 3, 71.The present report is based on studies in sheep experimentally infected with T. brzrcei. This was part of a major investigation of the pathology of the diseases caused in ruminants by T. brucei, T. vivax, and T. congolense.

Pathological Changes in Cattle Infected with Trypanosoma brucei

“…This investigation showed that Trypanosoma brucei can localize extravascularly in tissues of the ox and produce lesions similar to those reported in small ruminants [7,81 and laboratory rodents [3, 81. Tliere appears to be no other report of invasion of bovine tissues by 7. brucei.…”

“…Two 16-month-old cattle, a bull and heifer of the Zebu breed, were infected with T. brucei, strain 8/18, which had been used in a previous investigation of experimental disease in sheep [7]. Two million trypanosomes in 1 ml of rat blood were injected intravenously into each animal.…”

The Mechanisms of Anaemia in Trypanosomosis: A Review

“…The authors also reported that specific, non-specific antibody production was drastically reduced, delayed, and at the same time, anaemia was consistent. Several authors (Ikede & Losos, 1972;Mackenzie & Cruickshank, 1973;Mackenzie et al, 1978;Anosa & Isoun, 1983;Igbokwe, 1994) reported an overwhelming proliferation of tissue macrophages during trypanosomosis.…”

Review of Pathology of Diseases in Domestic and Laboratory Animals Caused by Trypanosoma congolense, T. vivax, T. brucei, T. rhodesiense and T. gambiense

“…We have studied the clinical signs, haematological, morbid anatomical, and histological findings in 33 sheep experimentally infected with T. brucei [153, 155,1901. The disease was characterized by unrelenting fever, progressive lethargy, dullness, and subcutaneous oedema of the head, limbs, and scrotum.…”