CHIKUNGUNYA VIRUS IN INDIA
Dr. Ashwani Agrawal*
Consultant Pediatrician, Raipur General Secretary, IAP CG State.*
Chikungunya Virus (CHIKV) is a mosquito-transmitted alphavirus belonging to family Togaviridae. It was isolated for the first from a Tanzanian outbreak in 1952. CHIKV is an enveloped, positive-strand RNA virus. To date, two CHIKV complete nucleotide sequences have determined, for the strains Ross and S27. It is responsible for an acute infection of abrupt of onset, characterized by high fever, arthralgia, myalgia, headache, and rash. Poly-arthralgia, the typical clinical sign of the disease, is very painful, symptoms are generally self limiting and last 1-10 days. However, arthralgia may persist for months or years. In some patients, minor hemorrhagic signs such as epistaxis or gingivorrhagia have also been described.
EPIDEMIOLOGY
CHIKV is geographically distributed in Africa, India, and South-East Asia. In Asia, CHIKV is transmitted from human mainly by A. aegypti and, to a lesser extent, by A. albopictus through an urban transmission cycle.

The last outbreak of chikungunya virus infection occurred in India in 1971. Subsequently, there has been no active or passive surveillance carried out in the country and therefore, it 'seemed' that the virus had 'disappeared' from the subcontinent. However, recent reports of large-scale outbreaks of fever caused by chikungunya virus infection in several parts of Southern India have confirmed the re-emergence of this virus. It has been estimated that over 1,80,000 cases have occurred in India since December 2005. Over 2000 cases of chikungunya fever have also been reported from Malegaon town in Nasik district, Maharashtra state, India between February-March 2006. During the same period, 4904 cases of fever associated with myalgia and headache have been reported from Orissa as well. According to the National Institute of Virology, Pune, out 362 samples collected from different places in AP, 139 were found positive for chikungunya, antibodies, six for dengue fever and 15 related to both the fevers.

The precise reasons for re-emergence of chikungunya in the Indian subcontinent are due to a variety of social, environmental, behavioral and biological changes, which of these contributed to the re-emergence of CHIKV would be interesting to unravel. A serosurvey conducted at Calcutta a decade ago did reveal that there is indeed lack of herd immunity to CHIVK. Yet another challenge faced during this large outbreak in the country has been the lack of rapid diagnostic facilities.
Clinical manifestations
CHIKV infection can cause a debilitating illness, most often characterized by fever, headache, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. The term 'chikungunya' is Swahili for 'that which bends up.'

The incubation period (time from illness) can be 2-12 days, but is usually 3-7 days. "Silent" CHIKV infections (infections without illness) do occur, but how commonly this happens is not yet known.

CHIKV is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on a person infected with CHIKV. Monkeys and possibly other wild animals, may also serve as reservoirs of the virus.Aedes aegypti, a household container breeder and aggressive daytime biter which is attracted to humans, is the primary vector of CHIKV to humans.

Acute chikungunya fever typically lasts a few to a couple of weeks, but as with dengue. West Nile fever, o'nyong-nyong fever and other arboviral fever, some patients have prolonged fatigue lasting several weeks. Additionally, some patients have reported incapacitating joint pain, or arthritis which may last for weeks or months. The prolonged joint pain associated with CHIVK is not typical of dengue. Co-circulation of dengue fever in many areas mean that chikungunya fever cases are sometimes clinically misdiagnosed as dengue infections, therefore the chikungunya fever could higher than what has been previously reported.

No deaths neuroinvasive cases, or hemorrhagic cases related to CHIVK infection have been conclusively documented in the scientific literature. However, neurological complications such as meningoencephalitis have been reported in a small proportion of patients during the first Indian outbreak as well as the recent French Reunion islands outbreaks.

CHIVK infection (whether clinical or silent) is thought to confer life-long immunity.
Treatment
No vaccine or specific antiviral treatment for chikungunya fever is available. Treatment is symptomatic; rest, fluids and ibuprofen, naproxen, acetaminophen, or paracetamol may relive symptoms of fever and aching. Aspirin should be avoided during the acute stages of the illness.

Infected persons should be protected from further mosquito exposure (staying indoors and/or under a mosquito net during the first few days of illness) so that they can't contribute to the transmission cycle.
Prevent
The best way to avoid CHIVK infection is to prevent mosquito bites. There is no vaccine or preventive drug. Prevention tips are similar to those for dengue or West Nile virus:
  • Use insect repellent containing a DEET or another EPA-registered active ingredient on exposed skin. Always follow the directions on the package.
  • Wear long sleeves and pants (ideally treat clothes with permethrin or another repellent).
  • Have secure screens on windows and doors to keep mosquitoes out.
  • Get rid of mosquito [A.aegypti] breeding sites by emptying standing water from flowerpots, buckets and barriers. If water storage is mandatory, a tight lid or thin layer of oil may prevent egg laying or hating.
  • Additionally, a person with chikungunya fever or dengue should limit their expose to mosquito bites in order to avoid further spreading the infection. The person should stay indoors or under mosquito net.
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