Study: Bacterium That Causes Q Fever Linked to Non-Hodgkin Lymphoma
Published on: October 13, 2015
(WASHINGTON, October, 13, 2015) –The bacterium that causes Q
fever, an infectious disease that humans contract from animals, is associated
with an increased risk of lymphoma, according to a study
published online today in Blood,
the Journal of the American Society of Hematology
Q fever is caused by infection with Coxiella burnetii,
a bacterium primarily transmitted through the excrements of cattle, sheep, and
goats. Approximately 3 percent of healthy adults in the United States and 10-20
percent of those in high-risk occupations such as veterinarians and farmers have antibodies
for C. burnetii, suggesting previous infection.
Symptoms of Q fever vary from person to person and can be acute and resolve
spontaneously, or chronic and persistent. Because some patients have been
reported to also suffer from lymphoma, researchers believed that this type of
cancer could be a risk factor for Q fever. However, the experience of one
patient prompted doctors to consider the opposite – that the infection might
actually cause the lymphoma.
“During a follow-up scan in a patient we had successfully
treated for Q fever, we observed a tumor close to the location of the previous
infection,” said senior study author Didier Raoult, MD, PhD, of Aix-Marseille
University in Marseille, France. “The discovery that it was a lymphoma tumor containing
C. burnetii encouraged us to consider that the infection might have
contributed to the development of the cancer.”
In order to better understand the association between C.
burnetii and lymphoma, Dr. Raoult and colleagues screened 1,468 patients treated
at the French National Referral Center for Q Fever from 2004 to 2014.
Investigators conducted imaging of patient tissue samples to identify seven people,
including the initial patient, who developed lymphoma after C. burnetii infection
(6 patients were diagnosed with diffuse large B-cell lymphoma and one with follicular
lymphoma). Of all the Q fever patients included in the study, 440 presented a persistent
infection concentrated to one area.
To determine if patients with Q fever have a higher risk of
lymphoma than the general population, researchers compared the incidence of
lymphoma in the Q fever registry to the incidence reported in France’s general
population. Based on this analysis, researchers conclude that patients with Q
fever are 25 times more likely to develop diffuse large B-cell lymphoma than those
without the infection. In addition, the odds of lymphoma in patients with
persistent concentrated infections are higher than those with other forms of Q
Upon further imaging of the patient samples, investigators
observed that Q fever patients with lymphoma demonstrate overproduction of the
critical anti-inflammatory pathway interleukin-10 (IL-10), suggesting that
suppression of the immune system may have allowed the lymphoma cells to evade
immune detection and multiply.
“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,” said Dr. Raoult.
“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 (www.bloodjournal.org), the most cited
peer-reviewed publication in the field of hematology, is available weekly in
print and online. Blood is the
official journal of the American Society of Hematology (ASH) (www.hematology.org), the world’s
largest professional society concerned with the causes and treatment of blood
ASH’s mission is
to further the understanding, diagnosis, treatment, and prevention of disorders
affecting blood, bone marrow, and the immunologic, hemostatic, and vascular
systems by promoting research, clinical care, education, training, and advocacy
blood® is a
registered trademark of the American Society of Hematology.
Centers for Disease Control and Prevention; Accessed from:
http://www.cdc.gov/qfever/symptoms/index.html (Accessed: 10/2015).
Szabo, American Society of Hematology
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