Chikungunya is viral fever caused by an alphavirus. Chikungunya is spread by the bite of Aedes and Culex mosquitoes.
This virus belongs to the genus Alphavirus in the Togaviridae family of viruses. Other Alphaviruses include the Sindbis, eastern and western encephalitis, Semliki Forest and Ross River viruses. The Togaviridae family also includes the genus Rubivirus to which Rubella belongs.
It is an insect-borne virus, of the genus, Alphavirus, that is transmitted to humans by virus-carrying Aedes mosquitoes. There have been recent outbreaks of CHIKV associated with severe morbidity. CHIKV causes an illness with symptoms similar to dengue fever. CHIKV manifests itself with an acute febrile phase of the illness lasts only two to five days. Followed by a prolonged arthralgic disease that affects the joints of the extremities. The pain associated with CHIKV infection of the joints persists for weeks or months.
It is a rare viral infection transmitted by the bite of an infected mosquito. It is characterized by a rash, fever, and severe joint pain (arthralgias) that usually lasts for three to seven days. Because of its effect on the joints, Chikungunya has been classified among the Arthritic Viruses. It primarily occurs in tropical areas of the world.
Chikungunya was first described in 1955, following an outbreak on the Makonde Plateau, along the border between Tanganyika and Mozambique in 1952.
Chikungunya is found in Africa, southern India, Pakistan, South-East Asia and the Philippines and occurs predominantly during the rainy season. The range of hosts includes humans, primates, other mammals, and birds. In October 2006, the World Health Organization (WHO) reported chikungunya fever outbreaks in eight states in India.
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Between March 2005 and February 2006, 1,722 cases of chikungunya were reported in La Reunion, an island in the Indian Ocean east of Madagascar (territory of France). Two-hundred deaths were attributed to chikungunya.
Signs and symptoms:
*joint pain with or without swelling (arthritis or arthralgia), typically in the knee, ankle and small joints of the extremities
*low back pain
*mild hemorrhaging may be present especially in children
Asymptomatic (“silent”) infections are common, and immunity is long lasting.
The incubation period of Chikungunya disease is from two to four days. Symptoms of the disease include a fever up to 39 C (102.2 F), a petechial or maculopapular rash of the trunk and occasionally the limbs, and arthralgia or arthritis affecting multiple joints. Other nonspecific symptoms can include headache, conjunctival injection, and slight photophobia. Typically, the fever lasts for two days and then ends abruptly. However, other symptoms, namely joint pain, intense headache, insomnia and an extreme degree of prostration last for a variable period; usually for about 5 to 7 days. Patients have complained of joint pains for much longer time periods depending on their age.
Common laboratory tests for chikungunya include RT-PCR, virus isolation, and serological tests.
*Virus isolation provides the most definitive diganosis but takes 1-2 weeks for completion and must be carried out in Biosafety level 3 laboratories. The technique involves exposing specific cell lines to samples from whole blood and identifying chikungunya virus-specific responses.
*RT-PCR using nested primer pairs to amplify several Chikungunya-specific genes from whole blood. Results can be determined in 1-2 days.
*Serological diagnosis requires a larger amount of blood than the other methods and uses an ELISA assay to measure Chikungunya-specific IgM levels. Results require 2-3 days and false positives can occur with infection via other related viruses such as O’nyong’nyong virus and Semliki Forest Virus.
Chikungunya virus is indigenous to tropical Africa and Asia, where it is transmitted to humans by the bite of infected mosquitoes, usually of the genus Aedes. CHIK fever epidemics are sustained by human-mosquito-human transmission. The word “chikungunya” is thought to derive from description in local dialect of the contorted posture of patients afflicted with the severe joint pain associated with this disease. The main virus reservoirs are monkeys, but other species can also be affected, including humans.
There are no specific treatments for Chikungunya. There is no vaccine currently available. A Phase II vaccine trial, sponsored by the US Government and published in the American Journal of Tropical Medicine and Hygiene in 2000, used a live, attenuated virus, developing viral resistance in 98% of those tested after 28 days and 85% still showed resistance after one year.
Chikungunya fever is not a life threatening infection. Symptomatic treatment for mitigating pain and fever using anti-inflammatory drugs along with rest usually suffices. While recovery from chikungunya is the expected outcome, convalescence can be prolonged (up to a year or more), and persistent joint pain may require analgesic (pain medication) and long-term anti-inflammatory therapy.
A serological test for Chikungunya is available from the University of Malaya in Kuala Lumpur, Malaysia.
Chloroquine is gaining ground as a possible treatment for the symptoms associated with chikungunya, and as an anti-inflammatory agent to combat the arthritis associated with Chikungunya virus. A University of Malaya study found that for arthritis-like symptoms that are not relieved by aspirin and non-steroidal anti-inflammatory drugs (NSAID), chloroquine phosphate (250 mg/day) has given promising results. Research by an Italian scientist, Andrea Savarino, and his colleagues together with a French government press release in March 2006 have added more credence to the claim that chloroquine might be effective in treating chikungunya. Unpublished studies in cell culture and monkeys show no effect of chloroquine treatment on reduction of chikungunya disease. The fact sheet on Chikungunya advises against using aspirin, ibuprofen, naproxen and other NSAIDs that are recommended for arthritic pain and fever.
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DNA vaccination is a technique for protecting an organism against disease by injecting it with genetically engineered DNA to produce an immunological response. Nucleic acid vaccines are still experimental, and have been applied to a number of viral, bacterial and parasitic models of disease, as well as to several tumour models. DNA vaccines have a number of advantages over conventional vaccines, including the ability to induce a wider range of immune response types.A recent study report that a novel consensus-based approach to vaccine design for Chikungunya virus, employing a DNA vaccine strategy. The vaccine cassette was designed based on CHIKV Capsid and Envelope specific consensus sequences with several modifications, including codon optimization, RNA optimization, the addition of a Kozak sequence, and a substituted immunoglobulin E leader sequence. Analysis of cellular immune responses, including epitope mapping, demonstrates that these constructs induces both potent and broad cellular immunity in mice. In addition, antibody ELISAs demonstrate that these synthetic immunogens are capable of inducing high titer antibodies capable of recognizing native antigen. Taken together, these results support further study of the use of consensus CHIKV antigens in a potential vaccine cocktail.
Recovery from the disease varies by age. Younger patients recover within 5 to 15 days; middle-aged patients recover in 1 to 2.5 months. Recovery is longer for the elderly. The severity of the disease as well as its duration is less in younger patients and pregnant women. In pregnant women, no untoward effects are noticed after the infection.
Ocular inflammation from Chikungunya may present as iridocyclitis, and have retinal lesions as well.
Pedal oedema (swelling of legs) is observed in many patients, the cause of which remains obscure as it is not related to any cardiovascular, renal or hepatic abnormalities.
The most effective means of prevention are those that protect against any contact with the disease-carrying mosquitoes. These include using insect repellents with substances like DEET (N,N-Diethyl-meta-toluamide; also known as N,N’-Diethyl-3-methylbenzamide or NNDB), icaridin (also known as picaridin and KBR3023), PMD (p-menthane-3,8-diol, a substance derived from the lemon eucalyptus tree), or IR3535. Wearing bite-proof long sleeves and trousers (pants) also offers protection. In addition, garments can be treated with pyrethroids, a class of insecticides that often has repellent properties. Vaporized pyrethroids (for example in mosquito coils) are also insect repellents. Securing screens on windows and doors will help to keep mosquitoes out of the house. In the case of the day active Aedes aegypti and Aedes albopictus, however, this will only have a limited effect, since many contacts between the vector and the host occur outside. Thus, mosquito control is especially important.
Preventive measures include the same as those for other mosquito-associated diseases (e.g. malaria, malaria, yellow fever, west nile virus).
No vaccine is available against this virus infection. Prevention is entirely dependent upon taking steps to avoid mosquito bites and elimination of mosquito breeding sites.
To avoid mosquito bites:
* Wear full sleeve clothes and long dresses to cover the limbs;
* Use mosquito coils, repellents and electric vapour mats during the daytime;
* Use mosquito nets – to protect babies, old people and others, who may rest during the day. The effectiveness of such nets can be improved by treating them with permethrin (pyrethroid insecticide). Curtains (cloth or bamboo) can also be treated with insecticide and hung at windows or doorways, to repel or kill mosquitoes.
Mosquitoes become infected when they bite people who are sick with chikungunya. Mosquito nets and mosquito nets and mosquito coils will effectively prevent mosquitoes from biting sick people.
To prevent mosquito breeding
The Aedes mosquitoes that transmit chikungunya breed in a wide variety of manmade containers which are common around human dwellings. These containers collect rainwater, and include discarded tires, flowerpots, old oil drums, animal water troughs, water storage vessels, and plastic food containers. These breeding sites can be eliminated by
*Draining water from coolers, tanks, barrels, drums and buckets, etc.;*Emptying coolers when not in use;
* Removing from the house all objects, e.g. plant saucers, etc. which have water collected in them
* Cooperating with the public health authorities in anti-mosquito measures.
Role of public health authorities
* National programme for prevention and control of vector borne diseases should be strengthened and efficiently implemented with multisectoral coordination
* Legislations for elimination of domestic/peridomestic mosquitogenic sites should be effectively enforced
*Communities must be made aware of the disease and their active cooperation in prevention and control measures elicited .
Read about other arboviral infections:
*Yellow Fever: The Disease and Symptoms
*Yellow Fever Infection: Historical Perspective
*Yellow Fever Vaccine: Disease Prevention
Chikungunya virus is an alphavirus closely related to the O’nyong’nyong virus, the Ross River virus in Australia, and the viruses that cause eastern equine encephalitis and western equine encephalitis
Chikungunya is generally spread through bites from Aedes aegypti mosquitoes, but recent research by the Pasteur Institute in Paris has suggested that chikungunya virus strains in the 2005-2006 Reunion Island outbreak incurred a mutation that facilitated transmission by Aedes albopictus (Tiger mosquito). Concurrent studies by arbovirologists at the University of Texas Medical Branch in Galveston Texas confirmed definitively that enhanced chikungunya virus infection of Aedes albopictus was caused by a point mutation in one of the viral envelope genes (E1). Enhanced transmission of chikungunya virus by Aedes albopictus could mean an increased risk for chikungunya outbreaks in other areas where the Asian tiger mosquito is present. A recent epidemic in Italy was likely perpetuated by Aedes albopictus.
In Africa, chikungunya is spread via a sylvatic cycle in which the virus largely resides in other primates in between human outbreaks.
The name is derived from the Makonde word meaning “that which bends up” in reference to the stooped posture developed as a result of the arthritic symptoms of the disease. The disease was first described by Marion Robinson and W.H.R. Lumsden in 1955, following an outbreak in 1952 on the Makonde Plateau, along the border between Mozambique and Tanganyika (the mainland part of modern day Tanzania).
According to the initial 1955 report about the epidemiology of the disease, the term chikungunya is derived from the Makonde root verb kungunyala, meaning to dry up or become contorted. In concurrent research, Robinson glossed the Makonde term more specifically as “that which bends up.” Subsequent authors apparently overlooked the references to the Makonde language and assumed that the term derived from Swahili, the lingua franca of the region. The erroneous attribution of the term as a Swahili word has been repeated in numerous print sources. Many other erroneous spellings and forms of the term are in common use including “Chicken guinea”, “Chicken gunaya,” and “Chickengunya”.
Since its discovery in Tanganyika, Africa in 1952, chikungunya virus outbreaks have occurred occasionally in Africa, South Asia, and Southeast Asia, but recent outbreaks have spread the disease over a wider range.
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Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.