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Food Security

J.J. Rodríguez Jerez

Grisc – Grup de Recerca en Gobernança del Risc (UAB)

Control the spread of the Q fever

26 February 2010

Photo: Andres Rueda

The Q Fever was first described in 1935 in some slaughterhouses in Australia. It started off by being called the unknown fever. Later it became known as the fever of Queensland, by origin, and by extrapolation, and finally got the name of Q fever.

The pathogen agent of the disease, the Coxiella burnetii bacterium, was discovered in 1937 by isolating the bacteria from one of the first patients. A year later, ticks from animals carrying the organism were found in Montana (USA). For this reason, it has long been known that it is a zoonosis (a disease transmitted from animals to people), with cows, sheep and goats as most commonly involved animal species.

Increased incidence

In Europe it is considered a rare disease, except in the Netherlands. The evolution in this region has been spectacular, in 2007 between 15 and 30 cases were reported annually. In 2008 it affected around 1,000 and, in 2009, about 2,500. As the increase in cases in Holland was described, in Germany the alert sounded, with 370 cases in 2008. Its spread by these two countries now concerns the European Union (EU), because of the possible extension to other member countries (in 2008 a total of 1,594 cases were collected throughout the Union, of which 116 are described in Spain).

The keys of the spread are related to a high density of goat farms, especially in times of calving (spring and fall). It is precisely there where the disease increase is being detected.

The European Commission has asked the EFSA a report on measures to manage the risk of Q fever Given this data, the European Commission has asked the European Food Safety Authority (EFSA), an urgent report on measures that should be applied on the mainland to manage the risk of this zoonosis. An evaluation of the effectiveness of measures such as vaccination, animal movement restrictions, bio-security measures or pharmaceutical treatments will be done.

From mild to very severe

After the first isolation of C. burnetii in 1937, there have been several studies that prove that the bacteria can be located in a variety of farm animals, domestic and wild, as well as birds and arthropods. Today, the only country that considers itself free from this disease is New Zealand.

People are contaminated by this pathogen mainly by inhalation of airborne dust particles, contaminated with traces of affected animals (milk, urine or faeces).

In the case of infected animals, the risk is transferred to the placenta of cows, sheep and goats and is designated as high risk. This is an occupational hazard for farmers, veterinarians or anyone who comes into contact with infected pregnant animals. Other transmission routes include tick bites and consumption of unpasteurized raw milk or not very mature cheese made with non heated treated milk. The transmission amongst affected people is very rare.

Q fever usually occurs without detectable symptoms in half of those affected. In the other half, most patients develop a syndrome similar to influenza with high fever, muscle pain, headaches, nausea and in some cases, vomiting. After a couple of weeks, it disappears without sequelae.

However, about half of these patients develop pneumonia and even hepatitis. After a few months, these symptoms resolve without further problems. In a small proportion, which can reach 10% of the total, the most serious signs are often complicated by inflammation of the lining of the heart (endocarditis). The inflammation may eventually lead to death within about 3% of patients.

To all these problems, the organism responsible for Q fever is among those involved in bioterrorism, given its spread through the air. Hence, it is understandable that it is seriously being evaluated as a risk for people's health in the short to medium term.

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