The rates of chronic disease and death from Q fever may be higher than previously thought, according to study results from California.
Q fever — or query fever — is caused by Coxiella burnetii and was first described in Southern California in 1947, Christine M. Akamine, MD, an internist in the department of internal medicine at Loma Linda University Health, and colleagues explained.
“The clinical manifestations of acute and chronic infection are often nonspecic and can be widely variable, which makes establishing the diagnosis challenging,” Akamine and colleagues wrote in The American Journal of Tropical Medicine and Hygiene. “Not many studies on Q fever in Southern California have been conducted recently, and to our knowledge, the most recent study was published in 2006 by Cone et al., who described six cases of Q fever which presented over 32 years in the Southern California desert.”
To contribute to the understanding of Q fever, Akamine and colleagues examined the cases of 20 patients diagnosed with Q fever at a Veterans Affairs hospital in Southern California between 2000 and 2016. According to the study, they reviewed charts to collect demographics, laboratory data, diagnostic imaging, risk factors and treatment regimens, and categorized cases as acute or chronic and confirmed or probable.
They found that 90% of patients presented with an acute febrile illness, and there was an average delay in ordering diagnostic serology from the time of symptom onset of 31.9 days for acute cases and 63 days for chronic cases. According to the study, 15% of patients progressed from acute to chronic infection, compared with past studies that showed less than 5% of cases progressed to chronic infection. Additionally, results showed that 22.2% of patients with chronic Q fever infection had endocarditis, 22.2% had endovascular infection and 11.1% had both endocarditis and endovascular infection.
Two patients died, a mortality rate five times higher than that occurring in Q fever cases reported to the CDC, Akamine and colleagues noted. The researchers added that of the patients who died, death attributed to Q fever was associated with an average diagnostic delay of 65.5 days.
“In conclusion, we recommend obtaining Q fever serology in all patients residing in endemic areas who present with a febrile illness and negative blood cultures. In our experience, involving infectious disease consultation early in the clinical course appears to shorten the time from symptom onset to diagnosis,” they wrote.
“Given the severity of Q fever endocarditis and noncardiac endovascular infections, systematic detection of C. burnetii with PCR and screening for valvular and vascular risk factors has been recommended. Reporting Q fever is reliant on the awareness of the disease and its endemic nature and a high threshold of suspicion by clinicians. Increasing physician awareness and, therefore, reporting of the disease, mandatory reporting of animal infection, and systematic seroprevalence studies in humans and animals would provide important information for the prevention of disease.” – by Caitlyn Stulpin
Disclosures: The authors report no relevant financial disclosures.