Seasonal prevalence of trypanosomosis, Glossina density and infection along the escarpment of Omo River, Loma district, southern Ethiopia

Abstract

Background The temporal information of trypanosomosis and tsetse apparent density is very limited in the southern part of the country. So, the study was conducted to estimate the temporal, dry and wet seasons, prevalence of cattle trypanosomosis, and tsetse fly apparent density and its infection by trypanosome along the escarpment of Omo River, Loma district, Southern Ethiopia. Methods A total of 964 cattle (482 in each seasons) were examined for trypanosomosis using buffy coat technique. For Glossina and biting flies study a total of 80 odor-baited, acetone and aged cow urine, NGU traps were deployed around the watering and grazing areas. Results The overall prevalence of cattle trypanosomosis was 4.98% of which 3.1% and 6.8% accounted to dry and wet seasons, respectively. The prevalence of trypanosomosis was significantly higher during wet season (OR = 1.93, P < 0.05), in poor body condition (OR = 3.71, P < 0.05) and in black coat colour (OR = 13.18, P < 0.05) animals. Two species of Trypanosome, T . congolense and T . vivax , were circulating in the area both in dry and wet seasons. A total of 327 Glossina (126 G . pallidipes and 201 G . fuscipes ) were traped by using odour baited 80 NGU traps. The overall apparent density of Glossina was 4.1 Flies/Trap/Day. Relatively higher Glossina/Trap/Day caught in wet season (4.9 Flies/Trap/Day) than dry season (3.3 Flies/Trap/Day). Two species of Glossina namely G . pallidipes and G . fuscipes were distributed in the study areas. From the flies caught 127 Glossina were randomly selected and dissected. The overall proportion of Glossina infection was 15% with higher proportion of infection in wet season (19.6%) than the dry season (11.3%). Higher infection proportion was observed in G . pallidipes . Conclusion Trypansomosis is the major challenge for cattle productivity in the district. So to reduce the impact trypanosomosis and Glossina active community participation can play a key role.

Seasonal Patterns: Bovine Trypanosomosis, Glossina pallidipes Density, and Infection in Rift Valleys of Gamo Zone, Southern Ethiopia

“…Two species of trypanosomes were identified in the current study areas, namely, T. congolense (68.85%) and T. vivax (31.15%). This study has confirmed the observation of ( 8 , 13 , 16 , 17 , 49 ) in different parts of Ethiopia. The relatively higher predominance of T. congolense infection in cattle suggests the increased contact of cattle with the savanna tsetse flies, particularly G. pallidipes , which are more efficient transmitters of T. congolense than T. vivax in East Africa ( 12 , 50 ).…”

“…Trypanosome parasites detected in the mouthpart only were considered in the group of Duttonella ( T. vivax ), those detected both in the mouthparts and midguts were Nanomonas ( T. congolense ), and those found in the midgut, salivary glands, and mouthparts were considered as Trypanozoon ( T. brucei ) ( 17 , 23 , 38 ). Immature infections considered when the trypanosome parasites were detected only in the midgut of the tsetse flies.…”

“…Immature infections considered when the trypanosome parasites were detected only in the midgut of the tsetse flies. Finally, Giemsa-stained smears were examined under oil immersion compound microscope ( × 100 magnification) for trypanosome species identification based on morphological appearances ( 17 , 38 , 39 ). The infection rate (IR) in each season was calculated using the following formula ( 37 ):…”

“…It is estimated that 10 to 14 million cattle heads in Ethiopia are exposed to the risk of trypanosomosis ( 14 ). Cattle production plays a key role in the livelihood of southern regions of Ethiopia, but their production potential is not fully utilized and challenged due to trypanosomosis ( 15 , 17 ).…”

“…The control interventions commonly used in Ethiopia include insecticidal pour-on, insecticide-impregnated traps and targets, and use of different trypanocidal drugs ( 8 , 16 ). However, information related to temporal and spatial dynamics of tsetse and trypanosomes remain very limited and may be a reason that control strategies are less effective and fail in endemic areas ( 17 , 23 ). Hence, the epidemiological knowledge on seasonal prevalence of bovine trypanosomosis and distribution of the tsetse fly are paramount in formulating appropriate strategies for the control of these problems ( 24 ).…”