Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Q fever is a disease caused by infection with Coxiella burnetii,[1] a bacterium that affects both humans and animals. This organism is uncommon but may be found in cattle, sheep, goats and other domestic mammals, including cats and dogs. The infection results from inhalation of contaminated particles in the air, and from contact with the vaginal mucus, milk, feces, urine or semen of infected animals. The incubation period is 9-40 days. It is considered possibly the most infectious disease in the world, as a human being can be infected by a single bacterium.[2]
It was first described by Edward Holbrook Derrick[3] in abattoir workers in Brisbane, Queensland, Australia. The “Q” stands for “query” and was applied at a time when the causative agent was unknown; it was chosen over suggestions of “abattoir fever” and “Queensland rickettsial fever”, to avoid directing negative connotations at either the cattle industry or the state of Queensland.[4]
The pathogen of Q fever was discovered in 1937, when Frank Macfarlane Burnet and Mavis Freeman isolated the bacterium from one of Derrick’s patients.[5] It was originally identified as a species of Rickettsia. H.R. Cox and Davis isolated it from ticks in Montana, USA in 1938,[6] and called it Rickettsia diasporica.[citation needed] R. diasporica was considered non-pathogenic until laboratory investigators were infected;[citation needed] it was officially renamed Coxiella burnetii the same year. It is a zoonotic disease whose most common animal reservoirs are cattle, sheep and goats. Coxiella burnetii is no longer regarded as closely related to Rickettsiae.
Incubation period is usually 2 to 3 weeks. The most common manifestation is flu-like symptoms with abrupt onset of fever, malaise, profuse perspiration, severe headache, myalgia (muscle pain), joint pain, loss of appetite, upper respiratory problems, dry cough, pleuritic pain, chills, confusion and gastro-intestinal symptoms such as nausea, vomiting and diarrhea. The fever lasts approximately 7 to 14 days.
During the course, the disease can progress to an atypical pneumonia, which can result in a life threatening acute respiratory distress syndrome (ARDS), whereby such symptoms usually occur during the first 4 to 5 days of infection.
Less often the Q fever causes (granulomatous) hepatitis which becomes symptomatic with malaise, fever, liver enlargement (hepatomegaly), pain in the right upper quadrant of the abdomen and jaundice (icterus). Retinal vasculitis is a rare manifestation of Q fever.[7]
The chronic form of Q fever is virtually identical to inflammation of the inner lining of the heart (endocarditis),[8] which can occur months or decades following the infection. It is usually deadly if untreated. However, with appropriate treatment the mortality falls to around 10%.
[tubepress mode=’tag’, tagValue=’Q fever’]