Small Bite: Big Threat: Chikungunya

who__240x240What is Chikungunya? 
Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash.

The disease shares some clinical signs with dengue, and can be misdiagnosed in areas where dengue is common. There is no cure for the disease. Treatment is focused on relieving the symptoms. The proximity of mosquito breeding sites to human habitation is a significant risk factor for chikungunya.

Since 2004, chikungunya fever has reached epidemic proportions, with considerable morbidity and suffering. The disease occurs in Africa, Asia and the Indian subcontinent. In recent decades mosquito vectors of chikungunya have spread to Europe and the Americas.

Chikungunya is a mosquito-borne viral disease first described during an outbreak in southern Tanzania in 1952. It is an RNA virus that belongs to the alphavirus genus of the family Togaviridae.

The name ‘chikungunya’ derives from a word in the Kimakonde language, meaning “to become contorted” and describes the stooped appearance of sufferers with joint pain (arthralgia).

Signs and symptoms
Chikungunya is characterized by an abrupt onset of fever frequently accompanied by joint pain. Other common signs and symptoms include muscle pain, headache, nausea, fatigue and rash. The joint pain is often very debilitating, but usually lasts for a few days or may be prolonged to weeks.

Most patients recover fully, but in some cases joint pain may persist for several months, or even years. Occasional cases of eye, neurological and heart complications have been reported, as well as gastrointestinal complaints.

Serious complications are not common, but in older people, the disease can contribute to the cause of death. Often symptoms in infected individuals are mild and the infection may go unrecognized, or be misdiagnosed in areas where dengue occurs.

Transmission
The virus is transmitted from human to human by the bites of infected female mosquitoes. Most commonly, the mosquitoes involved are Aedes aegypti and Aedes albopictus, two species which can also transmit other mosquito-borne viruses, including dengue.

These mosquitoes can be found biting throughout daylight hours, though there may be peaks of activity in the early morning and late afternoon. Both species are found biting outdoors, but Ae. aegypti will also readily feed indoors.

After the bite of an infected mosquito, onset of illness occurs usually between four and eight days but can range from two to 12 days.

Diagnosis
Several methods can be used for diagnosis.Serological tests, such as enzyme-linked immunosorbent assays (ELISA), may confirm the presence of IgM and IgG anti-chikungunya antibodies. IgM antibody levels are highest three to five weeks after the onset of illness and persist for about two months.

Samples collected during the first week after the onset of symptoms should be tested by both serological and virological methods (RT-PCR).

The virus may be isolated from the blood during the first few days of infection. Various reverse transcriptase–polymerase chain reaction (RT–PCR) methods are available but are of variable sensitivity. Some are suited to clinical diagnosis.

RT–PCR products from clinical samples may also be used for genotyping of the virus, allowing comparisons with virus samples from various geographical sources.

Is Chikungunya contagious?
Chikungunya is not a contagious disease. If one person is infected by Chikungunya, it does not spread to another person, unless a mosquito, the carrier of the disease, bites the infected person and then subsequently bites a non-infected person.

Treatment
There is no specific antiviral drug treatment for Chikungunya. Treatment is directed primarily at relieving the symptoms, including the joint pain using anti-pyretics, optimal analgesics and fluids. There is no commercial chikungunya vaccine.

Prevention and control
The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for chikungunya as well as for other diseases that these species transmit.

Prevention and control relies heavily on reducing the number of natural and artificial water-filled container habitats that support breeding of the mosquitoes. This requires mobilization of affected communities.

During outbreaks, insecticides may be sprayed to kill flying mosquitoes, applied to surfaces in and around containers where the mosquitoes land, and used to treat water in containers to kill the immature larvae.

For protection during outbreaks of chikungunya, clothing which minimizes skin exposure to the day-biting vectors is advised.

Repellents can be applied to exposed skin or to clothing in strict accordance with product label instructions. Repellents should contain DEET (N, N-diethyl-3-methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or icaridin (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-1-methylpropylester).

For those who sleep during the daytime, particularly young children, or sick or older people, insecticide treated mosquito nets afford good protection. Mosquito coils or other insecticide vaporizers may also reduce indoor biting.

Basic precautions should be taken by people traveling to risk areas and these include use of repellents, wearing long sleeves and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering.

Home Remedies

  1. Drinking coconut water has proven to be the most effective remedy for Chikungunya. It does not cure the disease but aids in recovery since it flushes out the toxins from the liver.
  2. Tulsi (holy basil) can be chewed or consumed in a paste form. This helps bring down fever.
  3. Garlic paste with pepper (in powder form) can be mixed and applied on the painful joints. Alternatively clove oil can be used with powdered pepper. This helps relieve joint pain.
  4. Carrots, rich in Vitamin A, must be consumed raw since it boosts immunity and helps relieve joint pain.
  5. Epsom Salt, known to ease stress and relax the body, relieves pain and muscle cramps. Fill your bath tub with warm water and add Epsom salt and a few neem leaves to relieve joint pain. Neem leaves acts as an anti-repellant and also protects the skin.

Disease outbreaks in India
A large outbreak of chikungunya in India occurred in 2006 and 2007. Several other countries in South-East Asia were also affected. Since 2005, India, Indonesia, Thailand, Maldives and Myanmar have reported over 1.9 million cases.

With Inputs from: World Health Organization
Image: WHO/A. Crump

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