Infectious Diseases A to Z - Q Fever

With this new column, Elite Healthcare will compile an index of various infectious diseases, with occasional highlights of emerging conditions.

Q Fever

General definition and information:

An extremely rare disease with a specific patient population, Q Fever is a condition that is spread to humans by animals and most commonly affects people who work in occupations include farming, veterinary medicine, dairy workers, animal research, ranching and rearing of livestock. Also more likely to be infected are those individuals who live or spend time near ranches and livestock facilities. Caused by inhaling dust particles contaminated by infected animals, which are most often sheep, goats, and cattle, Q fever develops as a result of the bacteria coxiella burnetii that naturally infects the animals that are found in the animals’ birth products (i.e. placenta, amniotic fluid), urine, feces, and milk. Symptoms include fever, cough, nausea, headache, fatigue, chest pain, weight loss, chills, and muscle pain. Characterized as either acute or chronic, Q fever can lead to serious complications and death if not treated correctly.

Causes & Modes of Transmission:

Inhaled infection remains the most common cause of illness among patients, and direct contact with an animal is not required to cause sickness, according to the Centers for Disease Control and Prevention (CDC). The disease may also be spread by eating contaminated, unpasteurized dairy products and, more rarely, through blood transfusion, from a pregnant woman to her fetus, or through sex. Bioterrorism exposure is also a potential source of transmission, according to the CDC, as C. burnetii has been described as a potential bioterroristic agent and has been previously weaponized for use in biological warfare. The CDC offers the Laboratory Response Network for a laboratory infrastructure and capacity to respond to biological and chemical terrorism, and other public health emergencies.1

A highly infectious agent, C. burnetii may be able to make someone sick with fewer than 10 bacteria. The bacteria C. is extremely resistant to heat, drying, and many common disinfectants, which lends to its ease of transmission. According to the CDC, the number of Q Fever cases per million persons varies state by state, with cases most frequently reported from western and plains states where ranching and livestock rearing are common.2 More than one-third of cases (35%) are reported from four states (California, Texas, Colorado, and Illinois).2 As of 2014, the highest incidence rates of Q Fever in the United States, meaning at least 1.0 cases per 1 million persons, were found in Arizona, Arkansas, Colorado, Idaho, Montana, Nebraska, North Dakota, Oregon, South Dakota, Utah, and West Virginia.2 According to the CDC, most cases of reported illnesses begin in the spring and early summer months (peaking in April and May), which coincides with increases in outdoor activity and with the birthing season for a number of domestic animal species.2 Patients with a history of valvular defects, arterial aneurisms, or vascular grafts are also at increased risk of developing chronic Q Fever, as are women infected by C. burnetii during pregnancy and those with immunosuppression, according to the CDC.

Treatment Strategies:

According to the CDC, most people who develop Q Fever will recover without antibiotic treatment, however, for people who develop Q Fever disease, doxycycline is recommended to be prescribed two weeks. Chronic Q Fever is considered to be life-threatening and requires several months of antibiotic treatment, including doxycycline and hydroxychloroquine. Healthcare providers are advised that pregnant women who are infected may be at risk for miscarriage, stillbirth, preterm delivery, or low infant birth weight. The condition can lead to inflammation and infection of many body organs, including endocarditis (infection of heart tissue), encephalitis (inflammation of central nervous system), pneumonia (inflammation of lungs), hepatitis (inflammation of the liver), and splenomegaly (enlargement of spleen). The CDC also warns that diagnosis of Q Fever is challenging due to several aspects, including that symptoms may vary from patient to patient and can be difficult to distinguish from other diseases.2 Furthermore, diagnostic tests based on the detection of antibodies will frequently appear negative in the first 7-15 days of illness.2 Healthcare providers should treat patients based on clinical suspicion alone and not wait for the return of confirmatory tests, CDC officials claim. Detection of C. burnetii DNA by polymerase chain reaction (PCR) can rapidly confirm an acute Q fever infection and samples are ideally taken during the first two weeks of illness and before or soon following doxycycline administration.2 The CDC also recommends the use of serologic tests in combination with PCR testing of whole blood or serum for definitive diagnosis in the early stages of the illness. Treatment should be initiated as soon as Q fever is suspected and should never be withheld pending the receipt of diagnostic test results, CDC officials advise. Laboratory testing plays the largest role in diagnosing patients with Q Fever and other bio-threat agents, according to the CDC.

Prevention Parameters:

Vaccines are not available in the United States for the prevention of Q Fever, according to the CDC. Healthcare providers can communicate to those at risk of the condition that reduced risk can be accomplished by avoiding contact with animals, especially while animals are giving birth. Avoiding the consumption of raw milk or raw milk products is also advised, and those who have been diagnosed and have a history of heart valve disease, blood vessel abnormalities, a weakened immune system, or are pregnant, should be considered at higher risk of developing chronic Q Fever.

References