Abstract

Objective: To investigate the pathological effect of experimental Trypanosoma congolense (T. congolense) infection on the testes and epididymis of Yankasa rams. Methods: Nine intact un-castrated rams were obtained and divided into 2 groups of 6 infected with 1伊106 T. congolense and 3 uninfected controls. Four infected and one uninfected control rams were sacrificed on Day 75 post infection and the remaining four rams (two each of infected and control groups) on Day 86 post infection. Results: All infected rams became parasitaemic within 7-11 days post infection with clinical trypanosomosis characterized by peri-orbital oedema and a transient period of scrotal oedema, this was followed by progressive decrease in scrotal size. At postmortem, the organs from infected rams were pale and emaciated but no observable lesion was seen in the uninfected control group. At histology, the testes showed areas of necrosis on the interstitial tissue characterized by destruction of cellular structures within the tissues and seminiferous tubules. There was moderate to severe testicular degeneration manifested by loss of tissue architecture and infiltration with macrophages, neutrophils, lymphocytes and plasma cells. Fibrous connective tissues were also seen in the testes of the infected rams indicative of replacement of normal cells by fibrous connective tissue. The epididymis of the infected rams had collection of some spermatocytes and desquamated epithelial cells in the epithelial ducts although others were devoid of spermatocytes in their ducts leading to loss of epididymal sperm reserves. However, these were not seen in the uninfected control rams. Conclusions: T. congolense causes testicular and epididymal damage which may render the rams infertile or sterile.

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