Q fever in pregnant goats: pathogenesis and excretion of Coxiella burnetii

PLoS One. 2012;7(11):e48949. doi: 10.1371/journal.pone.0048949. Epub 2012 Nov 9.

Abstract

Coxiella burnetii is an intracellular bacterial pathogen that causes Q fever. Infected pregnant goats are a major source of human infection. However, the tissue dissemination and excretion pathway of the pathogen in goats are still poorly understood. To better understand Q fever pathogenesis, we inoculated groups of pregnant goats via the intranasal route with a recent Dutch outbreak C. burnetii isolate. Tissue dissemination and excretion of the pathogen were followed for up to 95 days after parturition. Goats were successfully infected via the intranasal route. PCR and immunohistochemistry showed strong tropism of C. burnetii towards the placenta at two to four weeks after inoculation. Bacterial replication seemed to occur predominantly in the trophoblasts of the placenta and not in other organs of goats and kids. The amount of C. burnetii DNA in the organs of goats and kids increased towards parturition. After parturition it decreased to undetectable levels: after 81 days post-parturition in goats and after 28 days post-parturition in kids. Infected goats gave birth to live or dead kids. High numbers of C. burnetii were excreted during abortion, but also during parturition of liveborn kids. C. burnetii was not detected in faeces or vaginal mucus before parturition. Our results are the first to demonstrate that pregnant goats can be infected via the intranasal route. C. burnetii has a strong tropism for the trophoblasts of the placenta and is not excreted before parturition; pathogen excretion occurs during birth of dead as well as healthy animals. Besides abortions, normal deliveries in C. burnetii-infected goats should be considered as a major zoonotic risk for Q fever in humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Coxiella burnetii / genetics
  • Coxiella burnetii / isolation & purification
  • Coxiella burnetii / metabolism*
  • DNA, Bacterial
  • Feces / microbiology
  • Female
  • Goat Diseases / microbiology*
  • Goats
  • Milk / microbiology
  • Mucus / microbiology
  • Placenta / anatomy & histology
  • Placenta / pathology
  • Pregnancy
  • Pregnancy Complications, Infectious / microbiology
  • Pregnancy Complications, Infectious / veterinary*
  • Pregnancy Outcome
  • Q Fever / microbiology
  • Q Fever / veterinary*
  • Vagina

Substances

  • DNA, Bacterial

Grants and funding

This study was financially supported by the Dutch Ministry of Economic Affairs, Agriculture and Innovation (project number 1640020100) and by DG Sanco of the European Commission, European Union (decision 2011/89/EU). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.