BOVINE TRYPANOSOMOSIS: PARASITOLOGICAL PREVALENCE, VECTORIAL DENSITY AND TRYPANOCIDAL DRUG UTILIZATION PRACTICE IN TSETSE SUPPRESSION AND NON-SUPPRESSION AREAS OF SOUTH OMO ZONE, ETHIOPIA
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2019-06
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Abstract
Questionnaire survey to assess knowledge and attitude of trypanocidal drug utilization practices, entomological survey to know apparent cyclical vector density and other mechanical vectors responsible for trypanosome infection transmission and parasitological study to elucidate the prevalence of bovine trypanosome was conducted in tsetse suppression areas and tsetse non-suppression areas of South Omo Zone, Southern Ethiopia from November 2018- May 2019. SPSS version 20 and R- software packages were used to analyze collected field data. For questionnaire survey, 124 cattle owners from tsetse suppression areas and 60 cattle owners from tsetse non-suppression areas were interviewed about their knowledge, attitude and practice (KAP) of trypanocidal drug utilization and constraints of trypanosome infection in the area. Blood samples from 1284 local breed cattle; 642 samples during dry season (344 from tsetse suppression areas and 298 from tsetse non-suppression areas) and 642 during wet season (344 from tsetse suppression areas and 298 from tsetse non-suppression areas) were parasitologically examined by using buffy coat technique and thin blood smear method. For entomological survey, 96 NGU traps were deployed (64 traps in tsetse suppression areas, 32 traps in tsetse non-suppression areas) in suspected Glossina multiplication habitats. The overall prevalence of bovine trypanosome infection in South Omo zone was found to be 11.05% (142/1284). The overall seasonal prevalence of bovine trypanosome infection in South Omo zone was 14.33% (92/642) and 7.78% (50/642) for dry and wet seasons, respectively. There was a statistically significant difference (P <0.05) in disease prevalence between the two seasons. During dry season, only sex and the grazing system were significantly associated with trypanosome infection occurrence but in wet season none of the risk factors were statistically significant. Multiple logistic regression analysis of trypanosome infection prevalence indicated that sex, body condition score (BCS), grazing system and season were significantly associated (P<0.05) with the prevalence of the disease in tsetse suppression areas. However, only sex and season for tsetse non-suppression areas were significantly associated with the prevalence of trypanosome infection. Trypanosoma congolense (T. congolense) was the dominant trypanosome species; 80% and 71.64% respectively from tsetse suppression areas and for tsetse non-suppression areas followed by Trypanosoma vivax (T. vivax). Overall pooled mean packed cell volume (PCV) indicated parasitaemic animals (23.57±3.13) had significantly lower PCV than aparasitaemic animals (27.80±4.95) and animals examined during dry season (26.22±4.37) had lower mean PCV than animals examined during wet season with significant association. Similarly, parasitaemic animals from tsetse suppression areas (PCV= 23.76± 3.07) and tsetse non-suppression areas (PCV= 23.37±3.21) had significantly lower mean PCV than their aparasitaemic counterpart (tsetse suppression areas, PCV= 27.73±5.07 and tsetse non-suppression areas, PCV= 27.88±4.82). However, mean PCV of animals infected with T. congolense (23.59±3.22) was not statistically different (P > 0.05) from those animals infected with T. vivax (23.26±3.31). It was also indicated that the probability of anaemic animals to be parasitaemic was significantly higher (P < 0.05) than non-anaemic animals in both tsetse suppression areas and tsetse non-suppression areas. Entomological survey result revealed that 2.64 F/T/D and 2.03 F/T/D respectively from tsetse suppression areas and tsetse non-suppression areas during dry season and 0.42 F/T/D and 0.56 F/T/D during the wet season. Glossina pallidipes (G. pallidipes) was the only cyclical vector identified from the area along with numerous mechanical vectors of genus Tabanus, Stomoxys and Haematopota. Higher dependency of cattle owners on trypanocidal drugs to treat their sick animals and limited trypanocidal drug availability in the veterinary pharmaceutical market in conjunction with unsustainable and less participatory vector control activities may intensify the threat of the disease in the area. Furthermore, upsetting current prevalence report of the disease in such area with frequent trypanocidal drug usage and drug injection by unskilled herdsmen and owners report on trypanocidal drug treatment failure may point out the issue of trypanocidal drug resistance in the area. Therefore integrated and safe control and prevention effort should be engaged to uphold cattle production and productivity in the area.
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Trypanosomosis, Bovine, Prevalence