Q fever outbreaks in small ruminants and people in the Netherlands

Abstract

Q fever is an almost ubiquitous zoonosis caused by the highly resistant aerobic Gram-negative bacterium Coxiella burnetii. Cattle, sheep and goats are the primary animal reservoirs, but infection with this organism may occur in several animal species. Infected sheep and goats may abort, mainly in late pregnancy. The causative agent is shed in urine, vaginal fluids, faeces, milk and, in high concentrations, in birth fluids and placentas of infected small ruminants. Transmission to humans mainly occurs through the aerosol route. In the Netherlands, Q fever is not a newly recognized human disease; between 1978 and 2006, the average number of notifications per annum was 17. In 2007, 182 human cases were confirmed, mainly in the southern part of the country, in an area with a high density of large dairy goat farms. Q fever recurred in 2008, mainly in the same area and at the end of the year exactly 1000 human cases had been registered, making it the largest human outbreak ever recorded. In 2005, Q fever was diagnosed for the first time as a cause of abortion at two dairy goat farms. In 2006, 2007 and 2008, six, seven and seven new cases at dairy goat farms were confirmed, respectively. The infected dairy goat farms were mainly located in the same area where human cases occurred and they are considered the most plausible source of human infection although evidence is still inconclusive. In the same period, two cases of abortion caused by C. burnetii were confirmed at two dairy sheep farms, one in the southern and one in the northern part of the country however these two cases do not appear to be related to human cases. This article aims to describe the Q fever situation in the Netherlands in 2007 and 2008. It starts with an overview of the causal agent, the disease and its history and focuses on the sheep and goat industry in the Netherlands and the Q fever problems. Research has started and measures have been taken aimed at reducing the shedding of C. burnetii and thus environmental contamination, trying to reduce human exposure in 2010.