One Health approach to vector biology and epidemiology of arboviruses, Rickettsia,and protozoain smallholder livestock systems in western Kenya

Abstract

Background:Vector-borne pathogens (VBP) present a seriousthreat to both animal and humanhealth globally due to their zoonotic potential.‘One Health’ epidemio-surveillance systems that integrate human, animal, and arthropod vector facetsof VBP transmission enhance detection and can give rise to informed effective multi-sectoral vector-borne disease control options. The most important vectors are ticks and mosquitoes, which have a cosmopolitan distribution due to their ecological plasticity. Collectively,they transmit viral, bacterial,and protozoal pathogensin sub-Saharan Africa. The distributional ranges ofVBP areexpected to expand due to increased globaltravel and trade in goods and livestock. Arboviruses, such as Rift Valley fever (RVF), chikungunya, dengue, and Crimean-Congo haemorrhagic fever (CCHF), are endemic in East Africa with regular occurrence of outbreaks, whileRickettsia africaecauses African tick bite fever in travellerswith few clinical cases reported in local populations.Furthermore, the co-occurrence of these causes of febrile illness and malariacomplicates the diagnosis of feversin hospitals.Correspondingly, Theileria parvaand Anaplasma marginaleare serious constraints to cattle production in the region. The Lake Victoria basin that encompasses the East African community countriesof Kenya, Uganda, and Tanzaniahas,an ecology that is conducive for the endemic proliferation of mosquitoes and ticks, high livestock density under subsistence production system and is an important trade corridor for the East African community. These factors are likely to enhance circulation of zoonotic VBPs in the area. Therefore, this surveillance project in western Kenya sought to establishthe most important species of ticks and mosquitoes transmitting zoonotic pathogens among local livestock and human populations. It also sought to determine if livestock harbour thesepathogens as asymptomatic carriers for human infection, in which they may cause zoonotic febrile illness.