Chikungunya
Overview
Chikungunya is a viral infection transmitted by Aedes aegypti and Aedes albopictus mosquitos. It is an RNA virus belonging to the alphavirus genus of the family Togaviridae. The disease shares clinical signs with dengue and can be misdiagnosed in areas which are endemic to both diseases. The virus causes a sudden onset of fever and severe joint pain which can be debilitating. Chikungunya can be translated to ‘to become contorted’ which describes the appearance of individuals bent over with joint pain. Chikungunya is rarely fatal and is usually self-limiting with symptoms fully resolved within 2-12 days. Joint pain can last months in certain individuals. Once infected, an individual is likely to remain immune from future infections.
Chikungunya was previously believed to be a disease of the tropics with reported cases occurring in Africa, Asia and the Caribbean. In recent decades, Chikungunya has also been reported in
the Americas, Croatia, Italy and France. The most recent outbreak which
occurred in the Americas reported 24,682 confirmed cases during
2013-2014.
Signs and symptoms
The incubation period can last 2-12 days but usually averages 3-7 days
before signs and symptoms appear:
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Fever
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Arthralgia
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Myalgia
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Joint swelling
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Rash
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Fatigue
Cause
Chikungunya is spread to humans through the bite of an infected Aedes
aegypti or Aedes albopictus mosquito. These mosquitos feed in the
daytime, particularly around dusk and dawn. In the acute phase, the virus
is usually present in the skeletal muscles and joints. The exact entry of
the chikungunya virus into mammalian cells remains under investigation.
Recent research has suggested the virus can undergo genetic drifts to
acquire alternate entry mechanisms.
Risk factors / at risk groups
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Newborn babies infected around time of birth
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Individuals aged over 65
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Comorbidities of hypertension, diabetes and cardiovascular disease
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Post rainy season where mosquito populations are at their highest
Diagnosis / microbiology testing
Serum/plasma tests detect virus, viral nucleic acid or virus-specific IgM and neutralising antibodies.
Treatment
There is no specific antiviral drug treatment for chikungunya. Treatment is directed primarily at relieving the symptoms. Rest, analgesics, antipyretics and plenty of fluids are recommended.
Corticosteroids are not recommended due to the potential of immunosuppression.
The antiviral, Ribavirin, can be used where arthralgia has persisted longer than 2 weeks.
Vaccine / preventative measures
There is currently no vaccine for Chikungunya.
Preventative measures include:
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Staying in accommodation with air-conditioning/window and door screens
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Sleeping under a mosquito net if outside
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Avoiding stagnant bodies of water
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Wearing insect repellent which contains DEET on exposed skin
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Wearing permethrin-treated clothing
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Wearing long-sleeved tops and long trousers where possible

