C. burnetii Prevalence and Vaccination | CDC EID

EID Journal Home > Volume 17, Number 3–March 2011

Volume 17, Number 3–March 2011
Research
Reduction of Coxiella burnetii Prevalence by Vaccination of Goats and Sheep, the Netherlands
Lenny Hogerwerf, René van den Brom, Hendrik I.J. Roest, Annemarie Bouma, Piet Vellema, Maarten Pieterse, Daan Dercksen, and Mirjam Nielen

Author affiliations: Utrecht University, Utrecht, the Netherlands (L. Hogerwerf, A. Bouma, M. Pieterse, M. Nielen); Animal Health Service, Deventer, the Netherlands (R. van den Brom, P. Vellema, D. Dercksen); and Central Veterinary Institute of Wageningen UR, Lelystad, the Netherlands (H.I.J. Roest)

Suggested citation for this article

Abstract
Recently, the number of human Q fever cases in the Netherlands increased dramatically. In response to this increase, dairy goats and dairy sheep were vaccinated against Coxiella burnetii. All pregnant dairy goats and dairy sheep in herds positive for Q fever were culled. We identified the effect of vaccination on bacterial shedding by small ruminants. On the day of culling, samples of uterine fluid, vaginal mucus, and milk were obtained from 957 pregnant animals in 13 herds. Prevalence and bacterial load were reduced in vaccinated animals compared with unvaccinated animals. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and human exposure to C. burnetii.

Q fever, which is caused by Coxiella burnetii, is a worldwide zoonotic infectious disease, and ruminants are the main reservoir for human infections (1–3). Ruminant infections may occasionally result in abortions, which are associated with shedding of large amounts of bacteria in placentas and birth fluids (4). Human infections have been reported mainly in persons handling infected animals and their products (5–8). However, this disease has not been perceived as a major public health risk for the general population. In 2007, a major epidemic occurred in the general population in the Netherlands (9), which resulted in >2,300 reported cases in 2009. An explanation for the emergence of human Q fever was abortion clusters in goat herds beginning in 2005 within an intensified dairy goat production system (10–15). This hypothesis was substantiated by epidemiologic studies, which indicated a possible spatial link between dairy goat farms and human cases (16).

Reduction of the number of human cases was considered essential by public health authorities in the Netherlands. One of the intervention measures taken was vaccination of dairy goats against C. burnetii (17). This measure assumed that vaccination would reduce abortions and bacterial shedding to levels that would reduce the number of human cases in the following year. Vaccination began in 2008 and intensified in 2009. As the number of cases of C. burnetii infection in patients doubled in 2009, policymakers applied a precautionary principle and decided to cull all pregnant dairy goats or sheep on infected farms before the 2010 kidding season. This measure was implemented at the end of 2009 and thereby precluded any field analysis of vaccine efficacy in the spring of 2010. However, there was an opportunity to sample animals shortly after they were humanely killed. The purpose of this study was to quantify the effect of vaccination on bacterial load in excreta of pregnant animals.

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C. burnetii Prevalence and Vaccination | CDC EID


Suggested Citation for this Article
Hogerwerf L, van den Brom R, Roest HIJ, Bouma A, Vellema P, Pieterse M, et al. Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, the Netherlands. Emerg Infect Dis [serial on the Internet]. 2011 Mar [date cited].
http://www.cdc.gov/EID/content/17/3/379.htm

DOI: 10.3201/eid1703.101157


Comments to the Authors
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Lenny Hogerwerf, Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, the Netherlands; email: l.hogerwerf@uu.nl