Signs and symptoms Edit
The incubation period of the chikungunya virus ranges from one to twelve days, and is most typically three to seven.[12] The disease may be asymptomatic, but generally is not, as 72% to 97% of those infected will develop symptoms.[12] Characteristic symptoms include sudden onset with high fever, joint pain, and rash. Other symptoms may occur, including headache, fatigue, digestive complaints, and conjunctivitis.[2]
Information gained during recent epidemics suggests that chikungunya fever may result in a chronic phase as well as the phase of acute illness.[13] Within the acute phase, two stages have been identified: a viral stage during the first five to seven days, during which viremia occurs,[14] followed by a convalescent stage lasting approximately ten days, during which symptoms improve and the virus cannot be detected in the blood.[12] 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. 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.[14] 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.[15]
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.[16] Joint pain is reported in 87–98% of cases, and nearly always occurs in more than one joint, though joint swelling is uncommon.[12] 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.[13] 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.[12][13] Pain may also occur in the muscles or ligaments.
Rash occurs in 40-50% of cases, generally as a maculopapular rash occurring two to five days after onset of symptoms.[12] Digestive symptoms, including abdominal pain, nausea, vomiting or diarrhea, may also occur.[2][12][17] In more than half of cases, normal activity is limited by significant fatigue and pain.[12] Infrequently, inflammation of the eyes may occur in the form of iridocyclitis, or uveitis, and retinal lesions may occur.[18]
Rarely, neurological disorders have been reported in association with chickungunya virus, including Guillain-Barré syndrome, palsies, meningoencephalitis, flaccid paralysis and neuropathy.[2] 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.[14]