Epidemiology of Q-fever in domestic ruminants and humans in Africa. A systematic review

Abstract

Q-fever is a zoonotic infectious disease caused by the gram-negative, intracellular, spore-forming bacterium Coxiella burnetii . Infected ruminants (cattle, sheep, and goats) are the reservoirs of the pathogen and thus an important source of infection in humans. This systematic review aims to consolidate the knowledge and awareness of Q-fever in Africa and identify future research opportunities and possible interventions in low-resource settings. We review information on Q-fever epidemiology and the diagnostic challenges in humans and domestic ruminants in Africa from the last 23 years. Six databases including university repositories were searched for relevant articles. A total of 84 studies and 4 theses met the selection criteria and were thus included in the review. They include serological and molecular studies of Q-fever in humans or domestic ruminants in 24/54 African countries. The mean seroprevalence estimates were 16% (95%CI 11–23%) in humans; 14% (95%CI 10–20%) in cattle; 13% (95%CI 9–18%) in sheep; and 21% (95%CI 15–29%) in goats. The mean prevalence for molecular detection of the pathogen were 3% (95%CI 0–16%) in humans; 9% (95%CI 4–19%) in cattle; 16% (95%CI 5–41%) in sheep; and 23% (95%CI 20–80%) in goats. The number of studies that identified risk factors for exposure among domestic ruminants was: sex (n = 6), age (n = 17), contact with other animals (n = 5), lack of quarantine of newly purchased animals (n = 1), extensive grazing system (n = 4), herd size (2), history of abortion (n = 5), absence of vaccination (n = 2), and high temperature (n = 1). The number of studies that reported protective factors was: sanitation (n = 2), burying and/ or burning the aborted foetus (n = 2), and young (age) (n = 2). The studies that identified risk factors for human disease infection included: close contact to animals (n = 7), age (n = 3), and gender (n = 5), while those identifying protective factors included: living in non-irrigated areas (n = 1), awareness/knowledge about zoonosis (n = 1), rodent control (n = 1), sanitation/disinfection of equipment after and before use (n = 1), occasional grazing (n = 1), and do nothing to aborted materials (n = 1). Diagnostic challenges such as poverty, lack of a well-equipped laboratory with biosafety level 3 specific for Q-fever testing, unspecific and self-limiting clinical signs/symptoms, lack of gold standard test, and variation in test specificity and sensitivity were identified. The disease is likely to be widespread in Africa and of public importance and underreported thus ‘One Health’ approaches to future studies are recommended. Further studies should focus on concurrent studies of human and livestock populations. One Health Impact Statement This review applies to One Health stakeholders including, the public, players in the livestock value chain, animal/ human/ environmental health workers, policy makers, and other implementers. This review summarizes the available information regarding Q-fever ( Coxiella burnetii ) in animals and humans in Africa, providing new information on the magnitude of the disease, and risk factors for infection. This information highlights the need for collaboration among One Health stakeholders and multisectoral cooperation towards achieving the One Health goals. The sharing of knowledge generated through research from academic, non-academic, and local/ indigenous knowledge will allow a new foundation for disease control that is applicable and beneficial to all stakeholders under the One Health umbrella rather than academic scientists alone.

Global and regional seroprevalence of coxiellosis in small ruminants: A systematic review and meta‐analysis

“…Seroprevalence of coxiellosis was significantly higher in goats than in sheep in this meta-analysis. The findings of this study are in-line with the findings of other regional meta-analyses (Ahmadinezhad et al, 2022;Bwatota et al, 2022;Nokhodian et al, 2017). There is no con- breaks (Anastácio et al, 2022;Bauer et al, 2021).…”

“…The estimated prevalence of this study is similar to the findings of another meta‐analysis, which is based on data from the Eastern Mediterranean region (parts of Africa and the Middle East), which reported a high prevalence of coxiellosis in sheep (25.1%) and goats (28.1%) (Ahmadinezhad et al., 2022). The pooled estimates found in this study were higher than the reported pooled prevalence (sheep 13.00%, goats 21.00%) of another meta‐analysis that was conducted in Africa between 2000 and 2022 (Bwatota et al., 2022). The discrepancies are possibly due to differences in article inclusion criteria, search repositories and publication range limitation.…”

“…and 2022 (Bwatota et al, 2022). The discrepancies are possibly due to differences in article inclusion criteria, search repositories and publication range limitation.…”

“…The global epidemiology of coxiellosis in sheep and goats is not well known due to the apparent neglect of the disease by farmers and healthcare providers in many parts of the world. Several systematic review and/or meta‐analysis articles are available regarding the seroprevalence of coxiellosis in livestock in particular geographical locations, such as Africa (Bwatota et al., 2022; Vanderburg et al., 2014), the Eastern Mediterranean region (Ahmadinezhad et al., 2022), Iran (Mobarez et al., 2017; Nokhodian et al., 2017), Kenya (Njeru et al., 2016) and the USA (McQuiston & Childs, 2002). Although a pooled global prevalence is available in buffaloes (El‐Alfy et al., 2023) and horses (Marenzoni et al., 2013), it is not available in sheep and goats, to the best of the authors knowledge.…”

Seroprevalence and assessment of risk-factors associated with Coxiellosis in cattle in Toukh, Qalubyia

“…Moreover, a significantly elevated seroprevalence rate of (73.17%) was recorded when cattle shared an environment with small ruminants, this finding is in accordance with (Menadi et al, 2020). This might linked to the increased susceptibility of hosts, especially goats and sheep where they act as the most susceptible farm animals and at high risk, serving as potential carriers capable of transmitting the disease to other ruminants (Bwatota et al, 2022). Significantly, age and breed played crucial roles in impacting C. burnetii seroprevalence, particularly older cattle aged above 4 years, which exhibited a higher seroprevalence rate of (67.44%) followed by (40.63%) in the 2-4 years age category; meanwhile, the lowest seroprevalence rate of (20%) was observed in cattle under 2 years.…”