Fascioliasis in Kenya: a review

Fascioliasis is a disease of major public health, veterinary health and socio-economic importance in Kenya. The disease is classified as a Neglected Tropical Disease by the World Health Organisation with Fasciola hepatica and Fasciola gigantica being the leading causative agents of fascioliasis in the world. The primary definitive hosts of Fasciola parasites are domestic ruminants with humans being accidentally infected and mud snails of genera Radix spp. and Galba spp. serving as the intermediate hosts. However, information regarding fascioliasis in Kenya is sparse and scattered. A structured narrative review of fascioliasis in Kenya was conducted with an aim of addressing socio-economic factors associated with fascioliasis, the economic impact of fascioliasis, snail intermediate hosts that support the transmission of the disease, high risk areas/high endemic areas, wildlife ruminant hosts, control efforts used in curtailing transmission of fascioliasis, diagnosis and finally treatment of fascioliasis in Kenya. Relevant literature was identified through searches of PubMed/MEDLINE ( n = 5,003), Web of Science ( n = 9,014), Scopus ( n = 6,530) and Google scholar/WHO/other sources ( n = 7,510) using specific search terms and Boolean operators. Quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools matched to each study design, with SANRA guidelines being used to improve transparency and reproducibility. Studies were considered eligible when they reported findings directly relevant to fascioliasis in Kenya with particular emphasis being placed on primary studies that provided quantitative evidence on fascioliasis in Kenya. The final review included 72 studies. It was ascertained that poverty and rural communities are the two major socio-economic factors associated with fascioliasis in Kenya with the disease being shown to disproportionately affect impoverished and rural communities that have limited access to clean water and healthcare services. Water projects such as dams and irrigation schemes were also found to influence the occurrence and prevalence of fascioliasis in Kenya. Fasciola gigantica was found to be the most predominant Fasciola parasite that causes fascioliasis in Kenya with Fasciola hepatica being found to be less prevalent. Important snail intermediate hosts that were found as being vital for the transmission of fascioliasis in Kenya were Radix natalensis and Galba spp. snails. Financial losses instigated by liver condemnation due to Fasciola (liver fluke) infections was found to be one of the major negative economic impacts of fascioliasis in Kenya, followed by inflated agricultural operating costs, treatment costs, veterinary fees and increased labour costs spurred by the disease. Reduced productivity of livestock due to chronic fascioliasis also translates to economic losses. In regard to high risk areas, the former Western province was found to be the province with the highest risk of fascioliasis in Kenya. In terms of wild-ruminant hosts, elephants, African buffaloes and camels are the only ones to have been reported infected with fascioliasis. It was also ascertained that diagnosis of fascioliasis in Kenya primarily relies on coprological sedimentation techniques to detect Fasciola eggs in faeces, with less use of immunological and molecular techniques. Control efforts used to interrupt transmission of fascioliasis in Kenya involves improved animal husbandry practices such as feeding livestock clean pasture, home watering of livestock, routine deworming and snail control. Finally, it was ascertained that treatment of fascioliasis in Kenya primarily utilises Triclabendazole, the drug recommended by the World Health Organisation with plant anthelmintics slowly being adopted as an alternative because of costs associated with Triclabendazole, potential development of anthelmintic resistance and availability of easy to use plant resources. Based on the results herein, an integrated “One-Health” approach in the fight against fascioliasis in Kenya is highly recommended.