The risk of lymphoma is increased by infection with the bacterium that causes Q fever, French researchers report today.
Q fever is caused by infection with Coxiella burnetii, a bacterium that is contracted from animals – mainly cattle, sheep, and goats. It can be either acute or chronic and persistent. Among the general population of the USA, about 3% of individuals have been infected with C. burnetii. The rate is up to 20% for vets and farmers.
Dr Didier Raoult, of Aix-Marseille University in Marseille, France, and colleagues investigated the possible link with lymphoma. They looked at tissue samples from 1,468 patients with Q fever and compared the rate of lymphoma against the general population.
They concluded that patients with Q fever are 25 times more likely to develop diffuse large B-cell lymphoma than those without the infection. The lymphoma risk was highest for those with persistent Q fever infections. This may be due to suppression of the immune system, as Q fever causes overproduction of the important anti-inflammatory protein interleukin-10.
Details are published in the journal Blood.
Dr Raoult said: "During a follow-up scan in a patient we had successfully treated for Q fever, we observed a tumour close to the location of the previous infection. The discovery that it was a lymphoma tumour containing C. burnetii encouraged us to consider that the infection might have contributed to the development of the cancer.
"As we continue to learn more about the association between C. burnetii and lymphoma, these results should encourage clinicians to survey high-risk patients as early as possible for potential cancer.
"Ultimately, this early diagnosis and treatment would improve outcomes for Q fever patients who subsequently develop lymphoma, particularly those with B-cell non-Hodgkin lymphoma."
Blood 14 October 2015
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