An Updated Review of Ornithodoros Ticks as Reservoirs of African Swine Fever in Sub-Saharan Africa and Madagascar

Abstract

This updated review provides an overview of the available information on Ornithodoros ticks as reservoirs and biological vectors of the ASF virus in Africa and Indian Ocean islands in order to update the current knowledge in this field, inclusive of an overview of available methods to investigate the presence of ticks in the natural environment and in domestic pig premises. In addition, it highlights the major areas of research that require attention in order to guide future investigations and fill knowledge gaps. The available information suggests that current knowledge is clearly insufficient to develop risk-based control and prevention strategies, which should be based on a sound understanding of genotype distribution and the potential for spillover from the source population. Studies on tick biology in the natural and domestic cycle, including genetics and systematics, represent another important knowledge gap. Considering the rapidly changing dynamics affecting the African continent (demographic growth, agricultural expansion, habitat transformation), anthropogenic factors influencing tick population distribution and ASF virus (ASFV) evolution in Africa are anticipated and have been recorded in southern Africa. This dynamic context, together with the current global trends of ASFV dissemination, highlights the need to prioritize further investigation on the acarological aspects linked with ASF ecology and evolution.

Blood meal metabarcoding of the argasid tick (Ornithodoros turicata Dugès) reveals extensive vector‐host associations

“…The results of this study provide evidence of soft ticks and swine contact which could be occurring more frequently than previously known (Brown & Bevins, 2018; Herrera‐Ibatá et al., 2017; Wormington et al., 2019), aided in part by molecular methodological advancements. In addition, the simple CO 2 ‐baited sticky trap deployed into the burrows in LANWR represents a technique that is not widely used for collecting soft ticks in endemic or non‐endemic regions for ASFV (Jori et al., 2023). This technique can utilize dry ice, as in the current study, but also CO 2 cylinders or sugar‐yeast fermentation to increase the flexibility in diverse regions when resources are often limited.…”

“…Multiple Ornithodoros ticks, including O. turicata , are also competent vectors of African swine fever virus (ASFV). ASFV causes 100% mortality in domestic swine (Manzano‐Román et al., 2012), and is currently considered the most impactful disease for the pig production industry (Jori et al., 2023). ASFV is a DNA virus (family Asfiviridae) discovered in Africa that has emerged in Europe, Asia, and the Caribbean (Gonzales et al., 2021; Jean‐Pierre et al., 2022; Penrith et al., 2013).…”

“…Understanding the host preferences and blood-feeding habits of O. turicata contributes to informing preventive and control measure. This tool could also help identify soft tick-vertebrate host networks in other regions of the world such as Africa, Europe, and Asia where ASFV is endemic, which was recently highlighted as an important knowledge gap (Jori et al, 2023). vector-host associations and offers a promising perspective for biodiversity monitoring and disease control strategies.…”

Detection of antibodies against Ornithodoros moubata salivary antigens and their association with detection of African swine fever virus in pigs slaughtered in central Uganda

“…This study looked at pigs with antibodies against O. moubata , but O. porcinus porcinus is also present in Uganda ( 46 ) and O. savignyi is also a competent vector and is found in Africa ( 47 ). The salivary protein used to detect antibodies in the ELISA used in this study shows homology between O. moubata and O. savignyi but there was no information regarding its relationship to O. porcinus porcinus ( 28 ).…”

Host immune responses against African swine fever virus: Insights and challenges for vaccine development

“…), potentially serving as reservoirs that sustain infections for over five years, contributing to the endemicity of ASF within regions ( Penrith, 2020 ). Notably, ASFV persistence within ticks for extended periods, such as the documented four-year presence in unoccupied domestic pig premises in Madagascar, highlights the virus’s resilience ( Jori et al , 2023 ). The presence of ASF since its first documentation in Kenya in 1921 has led to its dissemination across African and non-African countries ( Fig.…”