Warning on Chikungunya virus

Fever, arthritis, and other symptoms occurring in people to who have recently traveled to islands in the Indian Ocean may signal infection with an imported virus called "chikungunya," reports a study in the May/June issue of the journal Medicine, published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

A group of French researchers report on the symptoms and outcomes of chikungunya virus infection in 47 patients seen at the Leveran Hospital in Marseilles. The lead author was Dr Fabrice Simon, a specialist in infectious and tropical diseases at the hospital.

All of the patients became ill during or shortly after travel to an island in the Indian Ocean. Most were French tourists who had recently visited Reunion or other Indian Ocean islands, while others were residents of the islands who became ill while traveling in France. Several cases occurred in people originally from the island of Comoros—there is a significant community of migrants from Comoros in Marseilles.

During the acute phase of the infection, which lasted seven to ten days, the main symptoms were fever and arthritis, most common in the fingers, wrists, toes, and ankles. About half of the patients also had a rash. Eight patients had to be hospitalized during the acute phase, including two with life-threatening disease.

In 38 of the 47 patients, symptoms continued beyond the first 10 days. This chronic phase of the infection was characterized by severe joint pain and inflammation, which severely limited the patients' ability to walk and perform everyday tasks. Some patients were so disabled that hospitalization was required.

The chronic phase of the disease resolved very slowly—over several months. Treatment was solely symptomatic: pain-relievers and anti-inflammatory drugs. Some patients improved with short-term steroid treatment. Even after six months, nearly half of patients continued to have symptoms. The infection was particularly painful and disabling for some elderly patients.

Chikungunya virus is one of a group of viruses called arboviruses, which includes West Nile virus. It comes from eastern Africa, where it is spread by mosquitoes. (In the Makonde language of Tanzania and Mozambique, "chikungunya" means "that which bends up"—describing the contorted posture caused by painful arthritis.)

Recently, Chikungunya virus has spread to Asia and India. In the past two years there has been an "explosive outbreak" of Chikungunya virus infection in the Indian Ocean islands—particularly on Reunion Island, where 35 percent of a population of 770,000 became infected over a 6-month period. In 2006, the U.S. Centers for Disease Control issued a warning about Chikungunya virus for people traveling to the Indian Ocean islands, as well as to India and Sri Lanka. (Travelers looking for the most recent updates can check the CDC's website: http://www.cdc.gov/travel/other/2006/chikungunya_india.htm.)

The new report from France shows that this potentially serious infection can easily be imported to Western countries by people who travel to areas where outbreaks of Chikungunya virus—sometimes called "CHIKV"—have occurred. As with other tropical diseases, Western physicians may be unfamiliar with the symptoms and course of the infection, which can lead to delays in making the correct diagnosis. "Physicians should consider CHIKV when presented with a patient with an unusual rheumatic syndrome after traveling to the tropics," Dr. Simon and colleagues conclude.