Chikungunya

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Annotated Information

Classification and Resources

ID 5
ICD-10
ICD-9-CM
OMIM
SNOMED-CT
Orphanet
MeSH
DO

Defination

Chikungunya (/ˌtʃɪkənˈɡʌnjə/ CHI-kən-GUUN-yə; Makonde for that which bends up) is an infection caused by the chikungunya virus The disease features the sudden onset of fever two to four days after exposure The fever usually lasts two to seven days, while accompanying joint pains typically last weeks or months but sometimes years The mortality rate is a little less than in , with the elderly or those with underlying chronic medical problems most likely having severe complications~The virus is passed to humans by two species of mosquito of the genus Aedes: A albopictus and A aegypti Animal reservoirs of the virus include monkeys, birds, cattle, and rodents This is in contrast to dengue, for which primates are the only hosts Since , the disease has occurred in outbreaks in Asia, Europe and the Americas~The best means of prevention is overall mosquito control and the avoidance of bites by mosquitoes in areas where the disease is common This may be partly achieved with the use of mosquito nets No specific treatment is known, but supportive care is recommended, including rest, fluids, and medications to reduce fever and joint pain~

Synonyms

Chikungunya fever  ;

Etiology

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Diagnosis

Chikungunya is diagnosed on the basis of clinical, epidemiological, and laboratory criteria Clinically, acute onset of high fever and severe joint pain would lead to suspicion of chikungunya Epidemiological criteria consist of whether the individual has traveled to or spent time in an area in which chikungunya is present within the last twelve days (ie the potential incubation period) Laboratory criteria include a decreased lymphocyte count consistent with viremia However a definitive laboratory diagnosis can be accomplished through viral isolation, RT-PCR, or serological diagnosis~The differential diagnosis may include infection with other mosquito-borne viruses, such as dengue or malaria, and infection with influenza Chronic recurrent polyarthralgia occurs in at least % of chikungunya patients one year after infection, whereas such symptoms are uncommon in dengue~Virus isolation provides the most definitive diagnosis, but takes one to two weeks for completion and must be carried out in biosafety level III 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 is used to amplify several chikungunya-specific genes from whole blood, generating thousands to millions of copies of the genes in order to identify them RT-PCR can also be used to quantify the viral load in the blood Using RT-PCR, diagnostic results can be available in one to two days Serological diagnosis requires a larger amount of blood than the other methods, and uses an ELISA assay to measure chikungunya-specific IgM levels in the blood serum One advantage offered by serological diagnosis is that serum IgM is detectable from days to months after the onset of symptoms, but drawbacks are that results may require two to three days, and false positives can occur with infection due to other related viruses, such as o'nyong'nyong virus and Semliki Forest virus~Presently, there is no specific way to test for chronic signs and symptoms associated with Chikungunya fever although nonspecific laboratory findings such as C reactive protein and elevated cytokines can correlate with disease activity~

Symptoms

Chikungunya is diagnosed on the basis of clinical, epidemiological, and laboratory criteria Clinically, acute onset of high fever and severe joint pain would lead to suspicion of chikungunya Epidemiological criteria consist of whether the individual has traveled to or spent time in an area in which chikungunya is present within the last twelve days (ie the potential incubation period) Laboratory criteria include a decreased lymphocyte count consistent with viremia However a definitive laboratory diagnosis can be accomplished through viral isolation, RT-PCR, or serological diagnosis~The differential diagnosis may include infection with other mosquito-borne viruses, such as dengue or malaria, and infection with influenza Chronic recurrent polyarthralgia occurs in at least % of chikungunya patients one year after infection, whereas such symptoms are uncommon in dengue~Virus isolation provides the most definitive diagnosis, but takes one to two weeks for completion and must be carried out in biosafety level III 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 is used to amplify several chikungunya-specific genes from whole blood, generating thousands to millions of copies of the genes in order to identify them RT-PCR can also be used to quantify the viral load in the blood Using RT-PCR, diagnostic results can be available in one to two days Serological diagnosis requires a larger amount of blood than the other methods, and uses an ELISA assay to measure chikungunya-specific IgM levels in the blood serum One advantage offered by serological diagnosis is that serum IgM is detectable from days to months after the onset of symptoms, but drawbacks are that results may require two to three days, and false positives can occur with infection due to other related viruses, such as o'nyong'nyong virus and Semliki Forest virus~Presently, there is no specific way to test for chronic signs and symptoms associated with Chikungunya fever although nonspecific laboratory findings such as C reactive protein and elevated cytokines can correlate with disease activity~

Treatment

The incubation period of the chikungunya virus ranges from one to twelve days, and is most typically three to seven The disease may be asymptomatic, but generally is not, as % to % of those infected will develop symptoms Characteristic symptoms include sudden onset with high fever, joint pain, and rash Other symptoms may occur, including headache, fatigue, digestive complaints, and conjunctivitis~Information gained during recent epidemics suggests that chikungunya fever may result in a chronic phase as well as the phase of acute illness Within the acute phase, two stages have been identified: a viral stage during the first five to seven days, during which viremia occurs, followed by a convalescent stage lasting approximately ten days, during which symptoms improve and the virus cannot be detected in the blood 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 ?°C (?°F) and sometimes reaching ?°C (?°F) and may be biphasic—lasting several days, breaking, and then returning Fever occurs with the onset of viremia, and 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~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 –% 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 been 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 Pain may also occur in the muscles or ligaments~Rash occurs in -% of cases, generally as a maculopapular rash occurring two to five days after onset of symptoms Digestive symptoms, including abdominal pain, nausea, vomiting or diarrhea, may also occur In more than half of cases, normal activity is limited by significant fatigue and pain Infrequently, inflammation of the eyes may occur in the form of iridocyclitis, or uveitis, and retinal lesions may occur~Rarely, neurological disorders have been reported in association with chickungunya virus, including Guillain-Barré syndrome, palsies, meningoencephalitis, flaccid paralysis and neuropathy In contrast to dengue fever, Chikungunya fever very rarely causes hemorrhagic complications Symptoms of bleeding should lead to consideration of alternative diagnoses or co-infection with dengue fever or coexisting congestive hepatopathy~Chronic disease[edit]~Observations during recent epidemics have suggested chikungunya may cause long-term symptoms following acute infection This condition has been termed chronic chikungunya virus-induced arthralgia Long-term symptoms are not an entirely new observation; long-term arthritis was observed following an outbreak in Common predictors of prolonged symptoms are increased age and prior rheumatological disease~During the La Reunion outbreak in , more than % of subjects over the age of reported long-term musculoskeletal pain with up to % of people reporting prolonged painful joints three years following initial infection A study of imported cases in France reported that % of people still suffered from arthralgia two years after acute infection Following a local epidemic of chikungunya in Italy, % of people reported muscle pains, joint pains, or asthenia at one year after acute infection~Currently, the cause of these chronic symptoms is not fully known Markers of autoimmune or rheumatoid disease have not been found in people reporting chronic symptoms However, some evidence from humans and animal models suggests chikungunya may be able to establish chronic infections within the host 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 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 weeks after inoculation, and was associated with chronic synovitis Similarly, another study reported detection of a viral reporter gene in joint tissue of mice for weeks after inoculation In a nonhuman primate model, chikungunya virus was found to persist in the spleen for at least six weeks~

Labs working on this disease

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References

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