Prevalence and pathology associated with caprine arthritis encephalitis disease in Kiambu, Nairobi and Machakos counties in Kenya

Abstract

Caprine arthritis encephalitis (CAE) is a disease complex that affects domestic goats of all ages and breeds. It is characterized clinically by paresis that progresses rapidly to paralysis in new born and young animals and high prevalence of chronic and persistent arthritis and mastitis in adults. A study was carried out to determine the prevalence and the lesions associated with clinical and sub-clinical cases of CAE in goats and sheep, in selected farms in Thika West district, Kiambu County and Langata district, Nairobi county. Goats and sheep from Matungulu district, Machakos county were used as controls. A total of 134, of 477 goats; and 90 of 280 sheep were randomly selected in these farms and blood samples collected for preparation of sera. The sera were tested for CAE using agar gel immunodiffusion _Ji}GID) and- competitive enzyme-linked immunosorbent assay (cELISA) tests. Seropositive animals were examined for gross and histopathology lesions of CAE. During the study period, no clinical CAE cases were encountered. All the 90 sheep tested, none was positive for CAEV antibodies on AGID or cELIS A tests. However, 8 of 134 goat samples were positive for CAEV antibodies on competitive ELISA resulting in prevalence of 5.97% in all farms. Five (5/77) of these were female goats and three (3/57) were male goats. All the positive goats were over 6 months in age. The positive cases were from Sophia Roses 1135 (2.86%), Kuraiha Estate 2/36 (5.56 %) both in Thika west district; Greenfield Estate 2/36 (5.56%) in Matungulu district; and Sunvalley Estate 3/27 (11.1 %) in Langata district.Five goats, 3 sero-positive and 2 sero-negative, aged 6 month and above were selected and purchased for pathological examinations. Two goats on gross examination, and all five goats on histopathology had lesions that were consistent with CAE. Statistically, using Mann-Witney non parametric method, there was no significant difference between sero-positive and sero-negative as far as histological lesions were concerned (p>O.05). Significant gross lesions were areas of collapse in the lungs, thickened intestinal mucosa; and enlarged mesenteric lymph nodes. On histopathology, lesions observed in the brain were lymphocytic infiltrations m periventricular, menmges and parenchyma; and hypertrophy and detachment of ependymal layer and perivascular cuffing. In the lungs, there was-.congestion, atelectasis, emphysema, thickened alveolar walls, aij:tl;J~phocytic infiltrations. Intestines showed thickened mucosa due to lymphocytic infiltrations and mesenteric lymph nodes showed lymphoid hyperplasia. Most of these lesions are consistent with cas~s of CAE, hence conclusion that CAE exists in goats in Nairobi, Kiambu and Machakos counties at a low prevalence rate causing subclinical disease with histopathological lesions but not in sheep. Extensive studies needs to be done in different areas and seasons for comprehensive measures and strategies to be put in place to control the spread of the disease within the country and prevent the importation of this disease from countries with high prevalence rates.