Serological evidence of single and mixed infections of Rift Valley fever virus, Brucella spp. and Coxiella burnetii in dromedary camels in Kenya

PLoS Negl Trop Dis. 2021 Mar 26;15(3):e0009275. doi: 10.1371/journal.pntd.0009275. eCollection 2021 Mar.

Abstract

Camels are increasingly becoming the livestock of choice for pastoralists reeling from effects of climate change in semi-arid and arid parts of Kenya. As the population of camels rises, better understanding of their role in the epidemiology of zoonotic diseases in Kenya is a public health priority. Rift Valley fever (RVF), brucellosis and Q fever are three of the top priority diseases in the country but the involvement of camels in the transmission dynamics of these diseases is poorly understood. We analyzed 120 camel serum samples from northern Kenya to establish seropositivity rates of the three pathogens and to characterize the infecting Brucella species using molecular assays. We found seropositivity of 24.2% (95% confidence interval [CI]: 16.5-31.8%) for Brucella, 20.8% (95% CI: 13.6-28.1%) and 14.2% (95% CI: 7.9-20.4%) for Coxiella burnetii and Rift valley fever virus respectively. We found 27.5% (95% CI: 19.5-35.5%) of the animals were seropositive for at least one pathogen and 13.3% (95% CI: 7.2-19.4%) were seropositive for at least two pathogens. B. melitensis was the only Brucella spp. detected. The high sero-positivity rates are indicative of the endemicity of these pathogens among camel populations and the possible role the species has in the epidemiology of zoonotic diseases. Considering the strong association between human infection and contact with livestock for most zoonotic infections in Kenya, there is immediate need to conduct further research to determine the role of camels in transmission of these zoonoses to other livestock species and humans. This information will be useful for designing more effective surveillance systems and intervention measures.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibodies, Bacterial / blood*
  • Antibodies, Viral / blood*
  • Brucella / immunology
  • Brucellosis / epidemiology*
  • Brucellosis / transmission
  • Camelus / microbiology*
  • Coxiella burnetii / immunology
  • Female
  • Humans
  • Kenya / epidemiology
  • Livestock / microbiology
  • Male
  • Q Fever / epidemiology*
  • Q Fever / transmission
  • Rift Valley Fever / epidemiology*
  • Rift Valley Fever / transmission
  • Rift Valley fever virus / immunology
  • Seroepidemiologic Studies

Substances

  • Antibodies, Bacterial
  • Antibodies, Viral

Grants and funding

This study was part of the project: Co-infection with Rift Valley fever virus, Brucella spp and Coxiella burnetii in humans and animals in Kenya: Disease burden and ecological factors that was funded by the United States Defense Threat Reduction Agency (GRANT 12686246_R, to BB). Additional funding for field work was provided by the Food and Agriculture Organization of the United Nations. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.