Q Fever

Unique identifier / Notation

BI0081

Synonyms

Query Fever

Coxiellosis

Abattoir fever

Q fever is a widespread zoonosis caused by the bacterium Coxiella burnetii. The respiratory tract is the most common route of infection, which occurs by inhalation of contaminated dust and spray shed from infected animals. Livestock, more specifically dairy goats and cows are considered as the major ‘source’ for human infections; dairy products from infected goats or cows are also an important source of infection (FAO, no date).

Primary reference(s)

FAO, no date. The AGRIS Database. Food and Agriculture Organization of the United Nations (FAO). Accessed 4 October 2020.

Additional scientific description

Q fever was first recognised as a human disease in Australia in 1935 and in the USA in the early 1940s. The ‘Q’ stands for ‘query’ and was applied at a time when the cause was unknown (CDC, 2019).

Q fever is a zoonotic disease caused by infection with Coxiella burnetii that affects humans and other animals. C. burnetii is uncommon, but may be found in cattle, sheep, goats, and other domestic mammals, including cats and dogs. Clinical cases seem to be most significant in sheep and goats, with sporadic losses and occasional outbreaks that may affect up to 50–90% of the herd. The infection results from inhalation of a spore-like small-cell variant, and from contact with the milk, urine, faeces, vaginal mucus, or semen of infected animals. Rarely, the disease is tick-borne (Spickler, 2017).

Humans are vulnerable to Q fever, and infection can result from even a few organisms. Some people never get sick; however, those who do usually develop flu-like symptoms including fever, chills, fatigue, and muscle pain (CDC, 2019). The main way of reducing the risk of being infected with Q fever is by avoiding contact with infected animals, especially while animals are giving birth. Be aware that animals can be infected with C. burnetii and appear healthy. People in direct contact with animals during birthing, such as veterinarians and farmers, may be at higher risk for infection. Abattoir workers are also at risk while being in contact with infected carcasses (Spickler, 2017).

Coxiella burnetii can survive for long periods in the environment and may be carried long distances by wind. Windborne outbreaks can affect dozens to hundreds of people who have no direct exposure to animals. In one exceptional incident, more than 4000 clinical cases were recognised in the Netherlands between 2007 and 2010. Efforts to end this outbreak resulted in temporary breeding bans and the culling of more than 50,000 small ruminants. The current state of knowledge about C. burnetii is incomplete, and some aspects of infections in humans and animals are still debated or not well understood (Spickler, 2017).

In humans, the incubation period for acute Q fever ranges from two days to six weeks, with most patients becoming ill within two to three weeks of exposure. Chronic Q fever is reported to develop months to years after infection, although some of the latter cases could result from delayed diagnosis. Studies from recent outbreaks in the Netherlands suggest that most cases of endocarditis can be detected within a few months to a year of infection (Spickler, 2017).

Coxiella burnetii has been found in most countries that have conducted surveillance. However, a few countries or areas, such as New Zealand, Norway, Iceland and French Polynesia, report that they have not found any evidence of this organism in surveys to date (Spickler, 2017).

Animal vaccination has been used in areas where infections are common. More generally, sanitary measures to remove afterbirth and birth fluids, and to clean and disinfect areas where animals have given birth can prevent the disease from spreading (OIE, no date).

Metrics and numeric limits

Not available.

Key relevant UN convention / multilateral treaty

Convention on the prohibition of the development, production and stockpiling of bacteriological (biological) and toxin weapons and on their Destruction (UNODA, no date).

International Health Regulations (2005), 3rd ed. (WHO, 2016).

WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (WTO, 1994).

UN Recommendations on the Transport of Dangerous Goods - UN Model Regulations Model Regulations Nature, Purpose and Significance of the Recommendations (UNECE, no date).