Seroprevalence and associated risk factors of brucellosis, Rift Valley fever and Q fever among settled and mobile agro-pastoralist communities and their livestock in Chad

PLoS Negl Trop Dis. 2023 Jun 23;17(6):e0011395. doi: 10.1371/journal.pntd.0011395. eCollection 2023 Jun.

Abstract

Brucellosis, Rift Valley fever (RVF) and Q fever are zoonoses prevalent in many developing countries, causing a high burden on human and animal health. Only a few studies are available on these among agro-pastoralist communities and their livestock in Chad. The objective of our study was to estimate brucellosis, RVF and Q fever seroprevalence among Chadian agro-pastoralist communities and their livestock, and to investigate risk factors for seropositivity. We conducted a multi-stage cross-sectional serological survey in two rural health districts, Yao and Danamadji (966 human and 1041 livestock (cattle, sheep, goat and equine) samples)). The true seroprevalence were calculated applying a Bayesian framework to adjust for imperfect diagnostic test characteristics and accounting for clustering in the study design. Risk factors for each of the zoonotic diseases were estimated using mixed effects logistic regression models. The overall prevalence for brucellosis, Q fever and RVF combined for both regions was estimated at 0.2% [95% credibility Interval: 0-1.1], 49.1% [%CI: 38.9-58.8] and 28.1% [%CI: 23.4-33.3] in humans, and 0.3% [%CI: 0-1.5], 12.8% [%CI: 9.7-16.4] and 10.2% [%CI: 7.6-13.4] in animals. Risk factors correlating significantly with the respective disease seropositivity were sex for human brucellosis, sex and Q fever co-infection for animal brucellosis, age for human Q fever, species and brucellosis co-infection for animal Q fever, age and herd-level animal RVF seroprevalence within the same cluster for human RVF, and cluster-level human RVF seroprevalence within the same cluster for animal RVF. In Danamadji and Yao, Q fever and RVF are notably seroprevalent among agro-pastoralist human and animal communities, while brucellosis appears to have a low prevalence. Correlation between the seroprevalence between humans and animals living in the same communities was detected for RVF, highlighting the interlinkage of human and animal transmissible diseases and of their health, highlighting the importance of a One Health approach.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bayes Theorem
  • Brucellosis* / epidemiology
  • Brucellosis* / veterinary
  • Cattle
  • Chad / epidemiology
  • Coinfection*
  • Cross-Sectional Studies
  • Goat Diseases* / epidemiology
  • Goats
  • Horses
  • Humans
  • Livestock
  • Q Fever* / epidemiology
  • Q Fever* / veterinary
  • Rift Valley Fever* / epidemiology
  • Rift Valley fever virus*
  • Risk Factors
  • Seroepidemiologic Studies
  • Sheep
  • Sheep Diseases* / epidemiology
  • Zoonoses / epidemiology

Grants and funding

This study was funded by the Swiss Federal Food Safety and Veterinary Office (https://www.blv.admin.ch/blv/en/home.html) by the grant number 1.17.o accquired by the authors SD and MFA and the Wolfermann-Nägeli Foundation (https://www.fundraiso.ch/en/sponsor/wolfermann-naegeli-stiftung) grant number 2016/19 accquired by the authors SD and MFA. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.