Elucidating Hard Ticks – Camels – Pathogens Interaction

Abstract

Infestations of ticks on hosts immensely impact human and animal health. Intrinsic to the capacity of these obligate hematophagous ectoparasites as vectors of animal and human diseases, is their ability to locate vertebrate hosts. Among livestock hosts (cattle, sheep, goat, and camels) of ticks, camel is the most preferred host by Hyalomma spp. Camel nostril is the most preferred predilection site and a very sensitive tissue and unsuitable for treatment with synthetic acaricides. Ticks are major vectors of tick-borne diseases (TBDs) in camels. The increasing prevalence and incidence of TBDs in camels coupled with acaricide resistance necessitates development of a control product that can be used to repel or lure ticks to where they can be exterminated using attract and kill approach. Thus, safer alternative ticks’ management approaches derived from the knowledge of chemo-ecological interactions between camel and ticks are urgently needed. This study researched camel-tick chemical communication to develop attractant formulation targeting all active camel-seeking stages of Hyalomma rufipes Olenev. The study described the diversity of ticks, established the prevalence of tick-borne pathogens (TBPs) in H. rufipes, the predominant ticks on camel, and the camel host in Marsabit and Samburu Counties. The study also identified camel volatile organic compounds (VOCs) associated with H. rufipes attraction and determined the behavioral responses of H. rufipes to selected VOCs. Molecular tools were used to characterize TBPs in the camels and ticks while the camel’s VOCs were analyzed using standard analytical tools and the selected VOCs were tested under laboratory conditions to determine behavioral responses of the ticks. With our ticks-hosts-pathogens interface studies, 14 species of ticks were found feeding on various livestock. Ticks showed a strong preference for one-humped camels (Camelus dromedarius). The camel nostril was the most preferred predilection site. The most prevalent tick species on camels was Hyalomma rufipes. Two novel Amblyomma gemma variants were found and characterized distinct both morphologically and genetically from

previously described Amblyomma gemma. The signature odors from camel breath and body were attractive to H. rufipes; demonstrating ticks utilize camel-derived metabolites to find their host. Our research shows that H. rufipes and camel hosts have unique and shared pathogens showing H. rufipes’ vector and camel’s reservoir host qualities. This study unravels the dynamic interactions between ticks, pathogens, and camels that all influence the likelihood of pathogen adaptation and transmission dynamics