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Chikungunya

Category: Illness or disabilities

Type

Involuntary

Introduction and description

Chikungunya fever is a viral disease transmitted to humans by the bite of infected mosquitos. Like malaria and dengue, this infection has almost become endemic in India, especially central and south India.

While the disease typically occurs in Africa and Asia, outbreaks have been reported in Europe and the Americas since the 2000s.

In 2014 more than a million suspected cases occurred. In 2014 it was occurring in Florida in the continental United States. The disease was first identified in 1952 in Tanzania. The term is from the Kimakonde language and means "to become contorted".

Symptoms

Symptoms typically occur two to twelve days after exposure.  The incubation period of the chikungunya virus ranges from one to twelve days, and is most typically three to seven.  The risk of death is around 1 in 1,000.  The very young, old, and those with other health problems are at risk of more severe disease.

Acute phase-  Symptoms include

  • Fever - Typically, the disease begins with a sudden high fever that lasts from a few days to a week, and sometimes up to ten days. The fever is usually above 39 °C (102 °F) and sometimes reaching 40 °C (104 °F) and may be biphasic—lasting several days, breaking, and then returning.
  • Inflammation of the eyes - may occur in the form of iridocyclitis, or uveitis, and retinal lesions
  • Chills
  • Headache
  • Insomnia
  • Liver damage - Temporary damage to the liver may occur.
  • Digestive symptoms -  including abdominal pain, nausea, vomiting or diarrhea
  • Joint pain with or without swelling, including low back pain
  • Rash - Rash occurs in 40–50% of cases, generally as a maculopapular rash occurring two to five days after onset of symptoms
  • Neurological disorders - have been reported in association with chikungunya virus, including Guillain–Barré syndrome, palsies, meningoencephalitis, flaccid paralysis and neuropathy

Symptoms are very similar to those of dengue but, unlike dengue, there is no haemorrhagic or shock syndrome form.

The level of virus in the blood correlates with the intensity of symptoms in the acute phase. When IgM, an antibody that is a response to the initial exposure to an antigen, appears in the blood, viremia begins to diminish. However, headache, insomnia and an extreme degree of exhaustion remain, usually about five to seven days.

Chronic phase - Following the fever, strong joint pain or stiffness occurs; it usually lasts weeks or months, but may last for years. The joint pain can be debilitating, often resulting in near immobility of the affected joints.  Joint pain is reported in 87–98% of cases, and nearly always occurs in more than one joint, though joint swelling is uncommon.

Typically the affected joints are located in both arms and legs, and are affected symmetrically. Joints are more likely to be affected if they have previously been damaged by disorders such as arthritis. Pain most commonly occurs in peripheral joints, such as the wrists, ankles, and joints of the hands and feet as well as some of the larger joints, typically the shoulders, elbows and knees

Cause

Chikungunya is an infection caused by the chikungunya virus (CHIKV).  Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus belonging to the Togaviridae family, first isolated in Tanzania in 1952. The main vectors are mosquitoes from the Aedes species - Aedes albopictus and Aedes aegypti. They mainly bite during the day. 

CHIKV has recently re-emerged causing millions of infections in countries around the Indian Ocean characterized by climate conditions favourable to high vector density. The virus may circulate within a number of animals including birds and rodents.

There is every indication that the virus exhibits latency.

During the La Reunion outbreak in 2006, more than 50% of subjects over the age of 45 reported long-term musculoskeletal pain with up to 60% of people reporting prolonged painful joints three years following initial infection. A study of imported cases in France reported that 59% of people still suffered from arthralgia two years after acute infection. Following a local epidemic of chikungunya in Italy, 66% of people reported muscle pains, joint pains, or asthenia at one year after acute infection

Viral antigen was detected in a muscle biopsy of a person suffering a recurrent episode of disease three months after initial onset. Additionally, viral antigen and viral RNA were found in macrophages in the synovial joint of a person experiencing a relapse of musculoskeletal disease 18 months after initial infection. Several animal models have also suggested chikungunya virus may establish persistent infections. In a mouse model, viral RNA was detected specifically in joint-associated tissue for at least 16 weeks after inoculation, and was associated with chronic synovitis

Treatment

Diagnosis is by either testing the blood for the virus's RNA or antibodies to the virus.  Chikungunya is a self-limiting illness with no specific treatment. Travellers visiting endemic areas should be careful and take precautions to see that they are not bitten by mosquitoes.


There is no specific therapy, and prevention is the main countermeasure. Prevention is based on insect control and in avoiding mosquito bites in endemic countries. Diagnosis is based on the detection of virus by molecular methods or by virus culture on the first days of infection, and by detection of an immune response in later stages. CHIKV infection must be suspected in patients with compatible clinical symptoms returning from epidemic/endemic areas. Differential diagnosis should take into account the cross-reactivity with other viruses from the same antigenic complex (i.e. O'nyong-nyong virus).  PMID:  23912863





References and further reading

  • J Assoc Physicians India. 2006 Sep;54:725-6. Chikungunya.  Kamath S1, Das AK, Parikh FS. - PMID:  17212022
  • Ozden S, Huerre M, Riviere JP, Coffey LL, Afonso PV, Mouly V, de Monredon J, Roger JC, El Amrani M, Yvin JL, Jaffar MC, Frenkiel MP, Sourisseau M, Schwartz O, Butler-Browne G, Desprès P, Gessain A, Ceccaldi PE (13 June 2007). "Human muscle satellite cells as targets of Chikungunya virus infection". PLoS ONE. 2 (6): e527. doi:10.1371/journal.pone.0000527. PMC 1885285. PMID 17565380
  • Hoarau JJ, Jaffar Bandjee MC, Krejbich Trotot P, Das T, Li-Pat-Yuen G, Dassa B, Denizot M, Guichard E, Ribera A, Henni T, Tallet F, Moiton MP, Gauzère BA, Bruniquet S, Jaffar Bandjee Z, Morbidelli P, Martigny G, Jolivet M, Gay F, Grandadam M, Tolou H, Vieillard V, Debré P, Autran B, Gasque P (15 May 2010). "Persistent chronic inflammation and infection by Chikungunya arthritogenic alphavirus in spite of a robust host immune response". Journal of Immunology. 184 (10): 5914–27. doi:10.4049/jimmunol.0900255. PMID 20404278
  • Labadie K, Larcher T, Joubert C, Mannioui A, Delache B, Brochard P, Guigand L, Dubreil L, Lebon P, Verrier B, de Lamballerie X, Suhrbier A, Cherel Y, Le Grand R, Roques P (March 2010). "Chikungunya disease in nonhuman primates involves long-term viral persistence in macrophages". The Journal of Clinical Investigation. 120 (3): 894–906. doi:10.1172/JCI40104. PMC 2827953. PMID 20179353

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