Understanding Q Fever Risk to Humans in Minnesota Through the Analysis of Spatiotemporal Trends

Alvarez Julio, Whitten Tory, Branscum Adam J., Garcia-Seco Teresa, Bender Jeff B., Scheftel Joni, and Perez Andres. Vector-Borne and Zoonotic Diseases. February 2018, 18(2): 89-95.  Published in Volume: 18 Issue 2: February 1, 2018

Understanding Q Fever Risk to Humans in Minnesota Through the Analysis of Spatiotemporal Trends

Q fever is a widely distributed, yet, neglected zoonotic disease, for which domestic ruminants are considered the main reservoirs in some countries. There are still many gaps in our knowledge of its epidemiology, and the source of sporadic cases is often not determined. In this study, we show how Q fever surveillance data in combination with information routinely collected by government agencies in Minnesota during 1997 to 2015 can be used to characterize patterns of occurrence of Q fever illnesses and detect variables potentially associated with increased human illness. Cluster analysis and Bayesian spatial regression modeling revealed the presence of areas in Southern Minnesota at higher risk of Q fever. The number of sheep flocks at the county level helped to explain the observed number of human cases, while no association with the cattle or goat population was observed. Our results provide information about the heterogeneous spatial distribution of risk of Q fever in Minnesota.


1280px-Coxiella_burnetii_01Image credit: en:Rocky Mountain Laboratories, NIAID, NIH


The causative agent of Q Fever, Coxiella burnetii, is a small Gram-negative bacterium morphologically similar to Rickettsia, but with genetic and physiological differences.  It has been isolated from approximately 40 species of ticks with possible tick borne transmission reported.  The most common mode of transmission is inhalation of infectious aerosols from fluids of infected animals.  It can become airborne and travel for miles causing outbreaks.  Person to person transmission is possible as well. It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the phagolysosome.  The CDC reports that 60% of cases are in patients without livestock contact (CDC unpublished data, 2010) and the need for health-care professionals to consider Q fever in the differential diagnosis in patients with a compatible illness, even in the absence of occupational risk or history of direct contact with animal reservoirs.

Supposedly, he United States ended its biological warfare program in 1969. When it did, C. burnetii was one of seven agents it had standardized as biological weapons.

Q Fever can cause acute or chronic illness.
Excellent video by Alicia Anderson, DVM, MPH on new CDC guidelines for Q Fever

Excerpts below:

Summary of Acute Q Fever
Prolonged fever (>10 days) with a normal leukocyte count, thrombocytopenia, and increased liver enzymes is suggestive of acute Q fever infection.
Children with Q fever generally have a milder acute illness than adults.
Children are more likely to have a rash than adults. Rash has been reported in up to 50% of children with acute Q fever.
Women infected with Q fever during pregnancy are at increased risk for miscarriage and preterm delivery.
Women of child-bearing age who receive a diagnosis of Q fever can benefit from pregnancy screening and counseling to guide health-care management decisions

Treatment: Symptomatic patients with confirmed or suspected acute Q fever, including children with severe infections, should be treated with doxycycline, which is most effective if given within the first 3 days of symptoms.  Other antibiotic regimens that can be used if doxycycline is contraindicated because of allergies include moxifloxacin, clarithromycin, trimethoprim/sulfamethoxazole, and rifampin.  Patients with acute Q fever should undergo a careful clinical assessment to determine whether they might be at risk for progression to chronic Q fever because patients at high risk require closer observation during the convalescent period.

Summary of Chronic Q Fever
Persons who are at high risk for development of chronic Q fever include persons with preexisting valvular heart disease, vascular grafts, or arterial aneurysms.
Infection during pregnancy and immunosuppression (e.g., from chemotherapy) are both conditions that have been linked to chronic Q fever development.
Endocarditis and infections of aneurysms or vascular prostheses are the most common forms of chronic Q fever and generally are fatal if untreated.
Chronic Q fever is rarely reported in children.
In contrast with adults, osteomyelitis is one of the most common findings in children with pediatric chronic Q fever.

Treatment:  Adults who receive a diagnosis of chronic Q fever should receive a treatment regimen of doxycycline and hydroxychloroquine (100 mg of doxycycline twice daily with 200 mg of hydroxychloroquine three times daily); duration of treatment might vary by the site of infection. A combination regimen is necessary to eradicate the organism because hydroxychloroquine raises the pH in the acidified phagosomal compartment and, in combination with doxycycline, has been shown to have in vitro bactericidal activity against C. burnetii. Because of potential retinal toxicity from long-term use of hydroxychloroquine, a baseline ophthalmic examination should be performed before treatment and every 6 months thereafter. Both doxycycline and hydroxychloroquine can cause photohypersensitivity, and hypersensitivity to sunlight is a potential complication with acute and chronic treatment regimens. Hydroxychloroquine is contraindicated in persons with glucose-6-phosphate dehydrogenase deficiency and persons with retinal or visual field deficits.

During treatment for chronic Q fever, patients should receive monthly serologic testing for C. burnetii phase I and II IgG and IgM antibodies and monthly clinical evaluations. If an appropriate treatment response is not achieved, monthly monitoring for hydroxychloroquine plasma levels (which should be maintained at 0.8–1.2 µg/mL) and doxycycline plasma levels (which should be maintained at ≥5 µg/mL) should also be performed during the treatment (145,146). Treatment should continue for at least 18 months for native valve infections and at least 24 months for prosthetic valve infections.

Rather than rely on indiscriminate application of predetermined cutoff titers, health-care providers should use serologic testing as a tool to ensure that the phase I IgG is decreasing during treatment in conjunction with recovery from clinical symptoms. A patient who has been treated appropriately for ≥18 months and has recovered from clinical symptoms but whose phase I IgG remains ≥1:1024 might not benefit from continued treatment.

See CDC link for treatment for pregnant women and children.

Q Fever is a notifiable disease in the U.S.