Transmitted to humans by the bite of infected mosquitos, the Chikungunya virus is a flu-like illness whose symptoms include fever, chills, headache and painful joints and muscles. The virus was discovered 50 years ago in Tanzania and has now spread throughout Africa and Asia. It can also cause a pruriginous skin eruption and gastrointestinal symptoms such as nausea and vomiting, in some cases. The illness develops benignly and ends abruptly within a few days, sometimes without the need to treat the symptoms. The joint pains may last for much longer, however.