Variation of sensitivity of Trypanosoma evansi isolates from Isiolo and Marsabit counties of Kenya to locally available trypanocidal drugs

Abstract

Trypanocidal resistance is a major cause of treatment failure. This study evaluated the sensitivity of Trypanosoma evansi field isolates collected from Marsabit and Isiolo counties, Kenya. A total of 2,750 camels were screened using parasitological tests for trypanosomes. Of the screened camels, 113 tested positive from which 40 T. evansi isolates were tested using the single dose mice sensitivity test. Five treatment groups each comprising of 6 mice were inoculated intraperitoneally with 1x105 trypanosomes of each isolate and treated 24 hours later with isometamidium chloride at 1 mg/kg, homidium chloride at 1mg/kg, diminazene aceturate at 20 mg/kg and quinapyramine sulphate & chloride at 1 mg/kg. The fifth group was left untreated (positive control). The mice were monitored daily for 60 days. A survey on camel owners’ practices that influence development of resistance to trypanocidal drugs was then conducted. Results indicated presence of drug resistance in all the 7 study sites that had infected camels. Seven of the isolates tested were resistant to diminazene aceturate whereas, 28, 33 and 34 were resistant to isometamidium chloride, quinapyramine sulphate & chloride and homidium chloride, respectively. Seven (17.5%) isolates of the 40 tested were sensitive to all 4 drugs, whereas, 7.5%, 10%,55% and 10% were resistant to 1,2,3 and 4 drugs, respectively. The prevalence of multiple drug resistance was 75%. Survey data indicated that camel management practices influenced the prevalence and degree of drug resistance. In conclusion, the multiple drug resistance observed in the two counties may not be an indication of total trypanocidal drug failure. Judicious treatment of confirmed trypanosomiasis cases with correct dosage would still be effective in controlling the disease since the observed resistance was at the population and not clonal level. However, integrated control of the disease and the vectors using available alternative methods is recommended to reduce drug use.

Spatial–Temporal Variations in Parasitological Prevalence and Host-Related Risk Factors of Camel Trypanosomiasis and Its Vectors in North Eastern Kenya: A Repeated Cross-Sectional Study

“…Herd prevalence variations were observed in the present study with the highest herd prevalence recorded in Loglogo (inhabited by the majority Rendille ethnic community) at the beginning of the dry season, followed by Kula Mawe (inhabited by the majority Borana ethnic community) during the rainy season, and finally Turbi (inhabited by the majority Gabbra ethnic community) at the peak of the dry season, which may be attributed to different Surra management practices by the communities as previously established [34]. Previous studies conducted in different localities in Somaliland and Ethiopia, both located in the Horn of Africa camel-keeping belt, reported comparable geographic [2,26] and herd [22] variations in trypanosomiasis prevalence.…”

“…This may be an indication that either the LMD area and/or the grazing areas of LMD camel keepers may not have biting flies or circulating trypanosome isolates or may point to better management practices and grazing patterns by the Somali ethnic community residing in the region. Indeed, our earlier survey on knowledge and trypanocidal use by the ethnic communities in the study area revealed that the Somali ethnic group residing in the LMD area were the most knowledgeable on camel Surra and recorded the highest prophylactic use of quinapyramine sulphate and chloride [34]. Nonetheless, the vector survey captured a few biting flies known to transmit trypanosome infection in the LMD region, although an assessment of fly infectivity was not carried out.…”

“…The high prevalence of trypanosomiasis infection recorded in some herds in the present study may be attributed to either a high population of biting flies or concentrated infections in places where the herds are grazed. Camel husbandry practices vary across the ethnic communities inhabiting different locations in the present study with some known to manage their camels better than others [13,34], which may also account to variations in Surra prevalence.…”

“…It is naturally expected that camel keepers would avoid grazing their camels in areas with a high population of biting flies to avoid infection and nuisance caused by the flies. Indeed, this is one of the coping mechanisms employed by camel keepers in the study setting to prevent Surra [34].…”

Putative bloodmeal sources in Glossina austeni tsetse fly of Arabuko Sokoke National Reserve in Kenya

“…The disease impacts impoverished livestock farmers and threatens food security and livelihoods. There are no effective vaccines against the trypanosome parasites [ 7 ] and most field trypanosome isolates have developed resistance against available antitrypanosomal drugs [ 8 , 9 ]. Prospects of using trypanotolerant cattle remain, but viability for wide scale adoption is not clear [ 10 ].…”