Chikungunya

The chikungunya virus is indigenous to Asia and Africa. It is transmitted to humans by the mosquitoe Aedes aegypti. Epidemics of chikungunya are continued by transmission of virus from human to mosquito and again to human. Aedes aegypti bites during day time and hence day time mosquito bite is the main reason for transmission. The virus is a heat sensitive RNA virus (family is Togaviridae and genus is alphavirus - Group IV+). There are three major groups of these viruses namely West African, central African and Asian.

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Signs and symptoms

The symptoms are similar to that of dengue fever. The disease takes places two to four days after the infection. The specific symptoms include fever up to 104 F (40 C). Fever is accompanied by petechial or maculopapular rash on the chest and sometimes on the limbs. Other symptoms may be slight photophobia, headache and infections of eye. Fever is for two days and ends unexpectedly but the other symptoms last for about a week. This period is variable.

The febrile part of the illness lasts for two to five days but there is an extended arthralgic phase. In this there is pain in joints of extremities and an extreme degree of prostration which persists for few weeks to months depending on the age. Inflammation of the feet may be seen in many patients but it is not related to renal, cardiovascular or hepatic disease. The reason behind this is not known.

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Tests and tools

Virus can be detected by RT-PCR, isolation of the virus and serological tests. RT- PCR requires one to two days, isolation also requires one to two weeks and it is the most specific test and serology requires two to three days, but is not specific.

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Treatment and prevention

At present any specific treatment is not available for Chikungunya. Medications are given for fever and arthritic pain. Prevention of mosquito bite by adopting precautionary measures though may help:

a) Precautions to reduce the risk of mosquito bite:-

Use mosquito net when sleeping during daytime.
Use curtains or window nets which prevent entry of mosquitos to the house.
Wear dress which covers most of the body. Also there are repellents available which can be applied on dress materials.
Use of cream or spray that can be applied on skin. This masks body odor and effectively you are invisible to mosquitoes. Very handy if you are visiting an area where Chikungunya is reported.
Use mosquito coils or repellents. But you should be aware that prolonged use of these is not recommended. Also ensure adequate ventilation when these are used.

b) Precautions to reduce mosquito breeding:-

Drain all the water collected around your house (for example in a pot or water cooler).
Ensure that drainages etc. are either closed or chemicals are applied which kill mosquito larvae (larvicides).
Another technique is to collect water in a container and once mosquitos lay eggs in it destroy them. This technique can be quite effective if multiple people apply it at their area.
If there is a pond which contains stagnant water, biological method is best. Fish varieties such as guppy can be introduced in the pond which will eat all the mosquito larvae.

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Expectations (Prognosis)

Prognosis depends on age of the patient. Younger patients recover fast than the aged. The recovery period for younger patients is five to fifteen days. For middle aged patients it is 1-2.5 months and for aged people the recovery period is still longer. The disease is less severe in young patients and pregnant women.

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Complications

The arthritic symptoms caused due to Chikungunya remain for longer time in older patients and affect daily activities. Ocular inflammation from Chikungunya may present as iridocyclitis, and have retinal lesions as well.

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Calling your health care provider

If any of the above mentioned symptoms are seen then it is better to seek medical advice.

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Prevention

Disease can be prevented by controlling mosquitoes. Therefore effective measures to control mosquitoes help in prevention of chikungunya. Vaccine for prevention of chikungunya is under research.

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