STUDY ON COMPARATIVE CLINICAL FEATURES AND DRUG RESISTANCE PATTERNS IN EXPERIMENTALLY INFECTEDGOATS WITHTRYPANOSOMA CONGOLENSE ISOLATES FROM TWO TSETSE INFESTED AREAS OF NORTHWEST ETHIOPIA

Abstract

Trypanosomosis ranks first in importance among protozoan infections of animals and man. This disease is a significant problem of livestock production in sub-Saharan Africa including in Ethiopia. Trypanosoma congolense is the most pathogenic trypanosome species infecting livestock. The current study was undertaken from December 2016 to May 2017 with the aim of characterizing and comparing the clinicopathological features, haemathological analysis and drug resistance patterns of T. congolense isolates from two tsetse infested areas of northwest Ethiopia. A total of 35trypanosome free goats were used for the experiment. These goats were randomly assigned in to 7 experimental groups (Group 1 JWI-1= experimental goats infected with T. congolense Jawi isolate, Group 2 JWI-DA= infected with Jawi isolate then treated with diminazine aceturate (DA), Group 3 JWI-ISM = infected with Jawi isolate then treated with isometamidium chloride (ISM), Group 4 JBI-1= experimental goats infected with T. congolense Jabitehenan isolate, Group 5 JBI-DA = infected with Jabitehenan isolate then treated with DA, Group 6 JBI-ISM = infected with Jabitehenan isolate then treated with ISM and Group 7 NIC = none infected controls) of five goats in each group. Each experimental animal except the Group 7 (NIC) was inoculated with 2 ml of infected blood collected from jugular vein of donor animals at a parasitaemia level of 1×106parasites/ml of blood. Experimental animals were observed daily for their clinical signs throughout the study period. Level of parasitaemia, body temperature, body weight, PCV and hemoglobin value were recorded daily until the detection of parasites and then continue twice a week until the end of the experiment. Trypanocidal treatment was given on day 14 post infection when peak parasitaemia was detected. 7mg/kg for Group 2 (JWI-DA) and Group 5 (JBI-DA) and 1mg/kg for Group 3 (JWI-ISM) and Group 6 (JBI-ISM) were the treatment doses for DA and ISM respectively. Trypanosomiasis was detected on day 5 and day 6 of post infection (Pi) in Jabitehenan and Jawi T. congolense isolates infected groups, respectively. All infected goats showed clinical manifestations of depression, weight loss, reduction of feed intake, swelling of superficial lymph node and anaemia. Significant (P < 0.05) reduction of the haematological values (mean PCV, total RBC, Hgb concentration and total WBC value) were observed in the infected groups compared to a none infected control group. The mean PCV, total RBC and Hgb concentration values of Jabitehenan isolate infected groups x were also significantly (P<0.05) lower than Jawi isolate infected groups. All of the infected control groups were get severe clinical signs and recumbence within 27-59 days of post infection. Severe clinical signs in group 4 (JBI-1) were occurred earlier as compared to experime ntal animals under group 1 (JWI-1). Neither of the DA nor ISM treatment groups attained complete recovery from trypanosome infection; rather relapsing was occurred since day 28 of pi. This finding concluded that T. congolense is highly pathogenic causing an acute forms of disease in animals accompanied by severe clinical signs with high percent of mortality; there was a presence of DA and ISM resistance problems for both T. congolense isolates; the presence of difference in clinical signs severity and time of occurrences starting from infection day between Jabitehenan and Jawi T.congolense isolates, indicating the presence of inter isolate difference of T.congolense parasites. Consequently, further molecular based study is essential and implementi ng of integrated control strategies is crucial to limit the problem in tsetse infested areas of northwest Ethiopia.