The Occurrence of Cystic Echinococcosis and Molecular Characterization From Livestock in Isiolo, Garissa and Wajir Counties, Kenya

Abstract

Cystic Echinococcosis (CE) is a zoonotic disease, spread worldwide and caused by the larvae of wild and domestic canids tapeworm, Echinococcus granulosus. Its prevalence in livestock has been reported in the wider African continent and in Kenya notably in the endemic regions of Maasailand and Turkana. Recent studies demonstrate its occurrence in non-endemic regions including Laikipia, Migori and Isiolo counties. CE‘s prevalence is high among rural pastoralist communities where socioeconomic and cultural conditions facilitate its transmission. Isiolo, Garissa and Wajir counties are regions with large numbers of pastoralist communities whose livelihood depends on livestock keeping. The current study aimed to estimate the prevalence of CE in livestock in the north-eastern counties of Kenya including Isiolo, Garissa and Wajir and characterize the species of E. granulosus sensu lato present. Slaughter house surveys was used. Data collected included the total number of animals slaughtered, species, number infected and location of the cyst. The data was analyzed using Stata 15 with risk factors associated with the disease occurrence analyzed at both univariable and multivariable levels using chi-square and logistic regression. The overall prevalence rates for CE included 29.1% in camels (68/234), 14.4% in bovines (17/118), 9.9% (68/689) in caprine and 8.2% in ovine (27/329). A total of 295 cysts were recovered from the 180 infected animals including 153(51.86%) from camels, 80(27.12%) from caprine, 35(11.36%) from ovine and 27(9.15%) from bovines. Isiolo County had the highest number of recovered cysts at 61.4% (181/295), Garissa County at 20.3% (60/295) and Wajir County at 18.3% (54/295). The liver was the most frequently infected organ with 72.88%(215/295) and 26.44%(78/295) from the lungs, the heart and masseter muscle each

had one cyst. Cysts termed fertile were only recovered from the lungs of camels in Isiolo county. There was a significant association between the county of animal origin and animal species with the occurrence of CE. Livestock in Isiolo county were more likely to be infected than those in Garissa and Wajir counties. Under similar environmental conditions, camels were more likely to be infected compared to the other livestock species. PCR-RFLP combined with the sequencing of the nad-1 gene was carried out to characterize the genotypes of Echinococcus granulosus as the pathogen is associated with extensive genetic variations. Echinococcus species identified were Echinococcus granulosus G1 and Echinococcus canadensis, G6 which are both zoonotic. G6 was the most dominant species recovered in the livestock species. In the sheep, G6 was the only recovered species as most cysts analyzed from sheep were from Isiolo county where camels were seen to be actively infected with G6. Mixed infections with Taeniid species was also noted. The findings here-in demonstrate the epidemiological situation in Isiolo, Garissa and Wajir counties which are emerging foci due to the huge slaughter volume with camels seen to play a key role in disease transmission. The G6 and G1 species were dominant in the study counties. Hence, similar studies that include molecular characterization of Echinococcus granulosus in livestock, humans and dogs should be carried out in the non-endemic areas to estimate the prevalence of the disease. In addition, dog population control coupled with community health education should be carried out.