Reproductive disorders caused by animal trypanosomiases: a review.

Pathogenic animal trypanosomes are causative agents of the most common livestock diseases which have an important economic impact on many African countries. These diseases usually cause debilitating symptoms manifested by anemia and cachexia which may result in death. Recent studies show that they cause a wide range of reproductive disorders in animals, including degeneration of the hypothalamus, pituitary glands and gonads with consequent disruptions in the secretions and plasma concentrations of the hormones necessary for normal reproductive processes in both sexes. Reproductive disorders caused in male animals include delayed puberty, loss of libido, severe degenerative changes of the genitalia manifested by the production of very poor quality semen or the cessation of semen production. In female animals trypanosomiases cause severe genital lesions, temporary or permanent anestrus, and abnormal estrous cycles. Additionally, trypanosomal-induced death during pregnancy, abnormal pregnancy, dystocia, abortion, premature birth, low birth weight, stillbirth, transplacental fetal infection, neonatal death and other pathogenic effects on fetuses and offspring have been reported. Early treatment with trypanocides may prevent some of the trypanosomal-induced reproductive disorders and the resolution of mild genital lesions. Trypanosomal-induced reproductive disorders in animals are of significant economic importance, especially in sub-Saharan Africa, where tsetse transmitted trypanosomiases are endemic.