Distribution and Prevalence of <i>Anaplasmataceae</i>, <i>Rickettsiaceae</i> and <i>Coxiellaceae</i> in African Ticks: A Systematic Review and Meta-Analysis.

Abstract

In Africa, ticks continue to be a major hindrance to the improvement of the livestock industry due to tick-borne pathogens that include <i>Anaplasma</i>, <i>Ehrlichia, Rickettsia</i> and <i>Coxiella</i> species. A systemic review and meta-analysis were conducted here and highlighted the distribution and prevalence of these tick-borne pathogens in African ticks. Relevant publications were searched in five electronic databases and selected using inclusion/exclusion criteria, resulting in 138 and 78 papers included in the qualitative and quantitative analysis, respectively. Most of the studies focused on <i>Rickettsia africae</i> (38 studies), followed by <i>Ehrlichia ruminantium</i> (27 studies), <i>Coxiella burnetii</i> (20 studies) and <i>Anaplasma marginale</i> (17 studies). A meta-analysis of proportions was performed using the random-effects model. The highest prevalence was obtained for <i>Rickettsia</i> spp. (18.39%; 95% CI: 14.23-22.85%), <i>R. africae</i> (13.47%; 95% CI: 2.76-28.69%), <i>R. conorii</i> (11.28%; 95% CI: 1.77-25.89%), <i>A. marginale</i> (12.75%; 95% CI: 4.06-24.35%), <i>E. ruminantium</i> (6.37%; 95% CI: 3.97-9.16%) and <i>E. canis</i> (4.3%; 95% CI: 0.04-12.66%). The prevalence of <i>C. burnetii</i> was low (0%; 95% CI: 0-0.25%), with higher prevalence for <i>Coxiella</i> spp. (27.02%; 95% CI: 10.83-46.03%) and <i>Coxiella</i>-like endosymbionts (70.47%; 95% CI: 27-99.82%). The effect of the tick genera, tick species, country and other variables were identified and highlighted the epidemiology of <i>Rhipicephalus</i> ticks in the heartwater; affinity of each <i>Rickettsia</i> species for different tick genera; dominant distribution of <i>A. marginale</i>, <i>R. africae</i> and <i>Coxiella</i>-like endosymbionts in ticks and a low distribution of <i>C. burnetii</i> in African hard ticks.