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Chikungunya.
Chikungunya is a viral fever caused by an alphavirus that is spread by bites from Aedes aegypti mosquitoes. Humans are the major reservoir of chikungunya virus. Mosquitoes usually transmit the disease by biting an infected person and then biting someone else. An infected person cannot spread the infection directly to other persons. Aedes aegypti mosquitoes bite during the day time.
In Swahili, chikungunya means "that which bends up" in reference to the stooped posture developed as a result of the arthritic symptoms of the disease.
Chikungunya is generally not fatal.
Incubation period varies from l to 12 days.
Clinical features
The symptoms of Chikungunya include fever, a maculopapular rash usually involving the limbs and trunk, and arthralgia or arthritis affecting multiple joints which can be debilitating.
Other symptoms include headache, conjunctival injection and slight photophobia.
Bleeding from skin (petechiae) and epistaxis may occur in some patients but bleeding from internal organs is unusual. Some patients may develop pedal oedema.
The fever usually lasts for 2-5 days and abruptly comes down. Other symptoms, particularly joint pains, headache and an extreme degree of prostration last for a variable period, usually for about 7-10 days. However, in some patients, joint pains may last for as long as 6 months. This is more common in elderly patients.
Diagnosis
Thrombocytopaenia may occur but is uncommon.
It is based on demonstrating antibodies using ELISA method.
In early stages, viral isolation confirms the diagnosis.
Molecular methods include reverse transcriptase polymerase chain reaction (RT-PCR) to detect structural genes in the blood sample.
Treatment
The treatment is symptomatic as there is no specific treatment for Chikungunya. For arthralgias and arthritis, ibuprofen, diclofenac or naproxen may be used. Rest is also important to reduce morbidity.
Chloroquine (150 base/day) may be tried in patients with prolonged symptoms.
Prevention
It is on similar lines as that for dengue infection.
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