The Chikungunya virus

The Chikungunya virus, an arbovirus, is an alphavirus belonging to the family of Togaviridae. The term chikungunya is Swahili ("that which bends up") referring to the stooped posture of patients with severe joint pain. The disease was first described in 1952-53 during an epidemic in East Africa.

Incubation period:
2-11 days (usually 3-7 days).

Clinical presentation:
3-25% of infections remain asymptomatic.

Self-limiting disease characterized by fever, chills, rash and symmetrical polyarthropathies, typically in the knees, ankles, and small joints of the extremities. Photophobia, conjunctivitis, pharyngitis, headaches, leukopenia, lymphadenopathies. Bleeding is rare. Evolution in two phases is possible. Convalescence is often prolonged.

Epidemiology:
Africa, Indian Ocean islands, Middle East, Asia (India), Australia and SE Asia. A large epidemic which began in late 2005 in various islands in the Indian Ocean, primarily Reunion Island, resulted in a number of cases imported into Europe, including with subsequent local transmission in Italy. Imported cases also continue to be reported in Europe and in the US (52 confirmed cases in 2006-07).

Aedes aegypti and others. Unknown reservoir; probably primates.

Mode of transmission:
Bite by infected mosquito.

Duration of contagiousness:
No human-to-human transmission.

Treatment:
Symptomatic.

Primary prevention:
Protection against insects (mosquitoes).