Researcher probes growing threat of Q fever

November 4, 2010

A researcher has questioned how many supposed cases of the flu might be attributable to another disease that can replicate in almost any animal, including horses, before infecting humans.


Coxiella burnetii, the bacteria that causes Q fever. © Rocky Mountain Laboratories/National Institute of Allergy and Infectious Diseases (NIAID)
Q fever is one of the most infectious diseases in the world, because it only takes one bacterium of Coxiella burnetii to infect the host.

It is found worldwide, except for New Zealand.

Sheep, goats and cattle are most likely to get Q fever. Other animals that can get the disease include dogs, cats, rabbits, horses, pigs, camels, buffalo, rodents, and some birds.

The Netherlands is the latest country to experience an outbreak. It reported 168 cases in 2007 and 2357 cases in 2009, according to the US Centers for Disease Control (CDC).

Because the Netherlands has determined the outbreak came from goats, officials slaughtered more than 50,000 dairy goats and vaccinated about 250,000 other animals.

Guoquan Zhang, an assistant professor in the Department of Veterinary Pathobiology in the College of Veterinary Medicine, has been working in the regional biocontainment laboratory on a vaccine safe for use in the US.

The US Food and Drug Administration has not approved the vaccine currently in use around the world, because if the Q fever bacteria is already present, a severe skin reaction could occur in those vaccinated.

Zhang's work focuses on finding a vaccine that doesn't cause that skin reaction.

The prevalence of Q fever is unknown because the symptoms - including fever, severe headache, cough, bodily pain and gastro-intestinal symptoms - mimic the flu so closely.

Symptoms typically do not surface for two to three weeks after exposure and it is possible for physicians to misdiagnose due to the prevalence of flu cases.

An antibiotic treatment makes it easy to recover, but Q fever can be confirmed only by a blood test.

Q fever is mostly transmitted through the air, but it can be acquired by drinking unpasteurized milk or from being bitten by a tick.

"While livestock like cows, sheep and goats are the common carriers of Coxiella burnetti, it has been found in pet animals such as cats, dogs, and birds," Zhang said.

"Once you have Q fever, it's very hard to get rid of it, especially if your immune system is already compromised from another health condition."

The CDC confirms that because Q fever can become airborne and is resistant to heat and drying, it has the potential to be a biological weapon.

US bio-weapon engineers developed Q fever as a weapon in the 1960s. Its ability to "incapacitate" without being lethal made it a preferable weapon.

Officials are concerned that soldiers returning from the Middle East may carry the bacteria.

Zhang has been receiving grants from the National Institute of Health to study Q fever.