[Exotic viral arthritis: role of alphavirus]

Only six of the many alphavirus known to affect humans can cause articular manifestations. They are the Ross River and Barmah Forest viruses from the South Pacific, the Chikungunya, O'Nyong Nyong and Sindbis viruses from tropical Africa, and the Mayaro virus from South America. In most cases, articular manifestations involve arthralgia or transient arthritis and are usually minor. However in some cases especially involving Ross River virus acute polyarthritis may be the most prominent clinical feature and even develop before fever. Although these joint symptoms may be severe and persist for weeks or months in a subacute mode with slightly inflammatory episodes that can be relieved using analgesics, they never cause permanent damage. Differential diagnosis of alphavirsus-related polyarthritis is simple to diagnosis especially in epidemic outbreaks as is frequently the case for Ross River virus epidemics in Australia. Imported cases should be suspected in patients presenting acute or subacute polyarthritis after a recent stay of any length of time in a tropical country and can be confirmed by ordering serology from a specialized reference laboratory.