Reliability of Some Clinical Parameters for Field Diagnosis of African Animal Trypanosomosis in Cattle

Abstract

Presumptive and inaccurate diagnosis of cattle trypanosomosis among field veterinarians has led to misuse of trypanocides, development of drug resistance, toxicities and huge economic losses. This study assessed the reliability, specificity and sensitivity of some identified trypanosomosis associated signalments (anaemia using FAMACHA® guide, body condition score (BCS), superficial lymph nodes enlargement and jugular pulsation) as field diagnostic parameters. Blood and faecal samples were collected from 273 subjectively selected cattle for the determination of packed cell volume (PCV) and screening for trypanosome, and for helminth egg using McMaster technique, respectively. Data obtained from assessment of packed cell volume based on BCS, FAMANCHA score, superficial lymph nodes enlargement and jugular pulsation were analyzed using descriptive statistics and Chi square, while comparison of data using independent student ttest and one-way ANOVA was similarly conducted. Of the screened cattle, 16.5% (45/273) were positive for trypanosome. Single infection due to Trypanosoma spp. was found in 13.5% (37/273) cattle, while 2.9% (8/273) had trypanosome concurrently with Babesia spp. or helminth infections. The prevalence of Trypanosoma infection was higher in animals with mild or moderately pale mucous membrane, slight emaciation, palpable superficial lymph nodes and pulsating jugular vein. The mean PCV of Trypanosoma infected cattle (27.65±0.056) was lower than in non-infected cattle (31.30±0.36) (p<0.05). Based on the jugular pulsation status, enlargement of the superficial lymph nodes, trypanosomosis state and Famancha category, there was no significant (p<0.05) variation in the PCV of the examined cattle. A negative and low correlation (r = -0.054) existed between BCS and FAMACHA® anaemia score. Each of the clinical diagnostic parameters showed poor sensitivity when employed separately, but the sensitivity improved when applied together and showed 80% specificity to Trypanosoma infection. The results of the present study showed that Trypanosoma infected cattle were associated with anaemia, emaciation, weight loss, jugular pulsation and lymphadenophathy.

Key Words: Trypanosomosis, Diagnosis, Cattle, Anaemia, Treatment