Coxiella burnetii infection (Q fever) in humans and animals: a generaloverview. -

Coxiella burnetii (C. burnetii), the causative agent of Q fever in humans and animals, is an obligate gram-negative intracellular bacterium of the family Coxiellaecae (Angelakis and Raoult, 2010). This bacterium can infect a wide range of hosts, but cattle, sheep and goats are the principal reservoirs (Angelakis and Raoult, 2010). Q fever is a zoonosis, and domestic ruminants such as cattle, sheep, and goats are considered the primary source of human infections (Maurin and Raoult, 1999; Angelakis and Raoult, 2010). C. burnetii infection can produce both acute and chronic forms of the disease in humans. A self-limiting febrile condition is the most frequent manifestation in most cases (Tissot-Dupont and Raoult, 2007). Spontaneous abortion, intrauterine foetal death, premature delivery or retarded intrauterine growth may occur in pregnant women (Carcopino et al., 2007). Mortality is a rare outcome of the acute form of the disease. The major clinical manifestation of chronic form of Q fever is endocarditis (Tissot-Dupont and Raoult, 2007) with case fatality in untreated cases exceeding 10% (Maurin and Raoult, 1999). Beside zoonotic importance, C. burnetii also produce health and production problems in domestic ruminants including cattle. Infection in cattle usually remains unrecognized (Rodolakis, 2009), but it causes sporadic reproductive problems such as abortion, infertility and mastitis (Barlow et al., 2008). These illustrate that C. burnetii infection does induce economic losses in dairy herds. Q fever was first reported amongst abattoir workers in Brisbane, Australia in 1935 as an outbreak of febrile illness and was codenamed ‘‘Q’’ for query fever (Derrick, 1937). However, McDade (1990) stated that Queensland was the state in which the ABSTRACT Coxiella burnetii, a ubiquitous intracellular bacterial pathogen, is the causative agent of zoonotic disease known as Q fever; with acute and chronic clinical manifestations. This bacterium is able to infect a wide range of animals, but cattle, sheep and goats are the principal reservoirs. It has been reported in many countries including Asian subcontinent like Bangladesh and India. Inhalation of contaminated aerosols is the main transmission route for humans. The spectrum of clinical manifestations in humans and animals are diverse, ranging from seroconvesion without any clinical symptoms to fatal consequences. The acute infection in humans manifests as self-limiting febrile illness, pneumonia, or hepatitis, whereas endocarditis is the major manifestation in chronic cases. Infection in domestic animal is usually asymptomatic and remains unrecognized, but it may cause abortion, especially in sheep and goat. Detection of high serum antibody titer or bacterial DNA from the aborted material or from milk and urine are the basis of confirmatory diagnosis of C. burnetii infection. Doxycycline and tetracyclines are the recommended antibiotic for humans. Cotrimoxazole and rifampin are the drugs of choice for the patients allergic or contradicted to tetracyclines. Oxytetracycline in the last trimester of pregnancy is usually recommended for animals. Control of Q fever in humans is largely dependent upon the control of infection in animals. Several preventive measures were suggested and have shown effective to prevent and reduce the animal and environmental contamination. Vaccination of animals against C. burnetii found to be effective for preventing abortion.