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Q Fever:
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Rickettsial agent acting on humans and livestock |
Synopsis, Diagnosis, Symptoms,
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Safety Precautions for Q fever Casualties |
Standard Precautions defined by the 1996 CDC guidelines should be adopted for handling patients.Airborne precautions may also be adopted.Biosafety level 2 or 3 practices should be adopted for handling of samples. |
| Causative organism: (Systematic name in 1997) |
Coxiella burnetii |
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| Older names: | Rickettsia burnetii |
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| Properties: | Small, non-motile lanceolate bacillus, often found as a diplobacillus.
(A small rod-shaped bacterium with pointed ends, do not move by their own power, often found in pairs) |
| Antibiotic treatments: |
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| Vector involvement: | The disease is spread in part by hard-bodied or ixodid ticks. |
| Epidemiology of natural outbreaks: | The disease can become established in wild animal hosts and livestock. People working with animal products, such as livestock farmers and slaughterhouse or leather workers are at greatest risk in natural outbreaks. Transmission has also been through contaminated milk. |
Q fever can be brought by the inhalation of a single organism, although it has a long incubation period of 14-26 days under such circumstances.
The symptoms of the disease are vague. Typically the patient has headache and fever (38.3-40°C (101-104°F)) and an atypical pneumonia (lungs look patchy on X-ray), fever, myalgia, sore throat and a cough that begins as unproductive and becomes paroxysmal. Rales is the most common physical finding.In some cases, the victim may present with acute hepatitis. In about 10% of cases, the heart is affected with destruction of the valves occurring several months after the initial infection.
Differential DiagnosisOther disease or conditions that need to be eliminated | |
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| Other infectious diseases | Other problems |
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Medical and Physical Countermeasures.
Vaccination (Immunoprophylaxis)
A vaccine, the IND610 inactivated whole cell vaccine, is available.
Vaccination with a single dose of this vaccine, a suspension of killed C. burnetii provides >90% protection against an aerosol exposure in human volunteers that last for at least five years. This vaccine can cause severe skin reactions including necrosis in some individuals, so a skin test is necessary before vaccination.
A second vaccine (Q-Vax) is available in Australia.
Antibiotics
The disease responds well to antibiotics. Tetracycline (500 mg every 6 hours) or doxycycline (100 mg every 12 hours) for 5-7 days is the treatment of choice. Erythromycin (500 mg every six hours) in combination with rifampin (600 mg per day) is also effective.
Supportive care
Neurological symptoms, malaise and fatigue may last for months in up to a third of patients. Chronic infection may lead to endocarditis.
Decontamination
The agent is very hardy and is resistant to some disinfectants. Sodium hypochlorite, formalin, ethanol, glutaraldehyde and gaseous formaldehyde may be used. Heat at 130°C for 60 min may be used and gamma irradiation is effective.
Agent Properties and Potential Uses
The agent is highly infective, with a single bacterium capable of giving rise to the disease. It occurs naturally in livestock (sheep, cattle, goats) that could form reservoirs in the wake of an attack. It can be grown to very high densities in chick embryo culture. It is also very hardy for a non-sporulating organism and can be easily stored and distributed as an aerosol over a wide range of temperatures (-52° to +40°C, -60° to +104°F) and is not affected by hot dry conditions.
The organism can enter a spore-like condition that allows significant distribution of the agent by the wind. It could be distributed as a dry powder rather than an aerosol.
The disease is incapacitating and rarely lethal with < 1% fatalities.
Ken Alibek (formerly Kanatjan Alibekov) a former senior scientist in the Soviet BW program reports that the Soviet Union was working on the use of the organism before World War II and he believes that an outbreak of Q fever in German forces in Russia during the war had the properties expected of deliberate use of the agent.
Terrorist Acquisition and Attempted Use.
| Disease | ICD-9-CM | ICD-10 |
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| Q fever | 083.0 | A78 |
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