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.

Over the past ten years, many studies demonstrated the crucial role of the tick microbiome in tick biology. The soft tick Ornithodoros moubata is a hematophagous ectoparasite of Suidae particularly known to transmit the African swine fever virus. Its bacterial microbiota is characterized by a high prevalence of Francisella-like and Rickettsia endosymbionts. The present study aims to better understand the potential influence of the microbiota on the reproductive fitness of O. moubata. A total of 132 adult female ticks were treated using gentamycin or rifampicin added to the blood meal. Half of the ticks also received a supplementation with B vitamins to address the nutritional role of endosymbionts. Over two periods of 50 days, several traits related to the reproductive fitness were monitored to investigate the importance of Francisella and Rickettsia for those traits. It appeared that most of the considered reproductive parameters were not affected. However, antibiotic treatments induced an increase in the tick survival indicating a potential fitness cost of harboring endosymbionts for ticks during the reproduction period. Similarly, 366 first stage nymphs of Ornithodoros moubata were exposed to the same treatments for molecular quantification of both endosymbionts. Results from qPCR suggested that treatments produced a bacteriostatic effect on endosymbionts without fully eliminating Francisella or Rickettsia.