Scientists start to unravel chikungungya mystery

23rd May 2006, Comments 0 comments

PARIS, May 23, 2006 (AFP) - French researchers said Tuesday an epidemic of the disease known as chikungunya, which ravaged the Indian Ocean island of Réunion, was spurred by a mutated form of a mosquito-borne virus.

PARIS, May 23, 2006 (AFP) - French researchers said Tuesday an epidemic of the disease known as chikungunya, which ravaged the Indian Ocean island of Réunion, was spurred by a mutated form of a mosquito-borne virus.

The chikungunya virus is typically spread by the yellow fever mosquito (Aedes aegypti).

But sequencing of a gene, E1, which allows the virus to attach to mosquito cellular membranes, suggests the pathogen may also be carried by another species, the Asian tiger mosquito (Aedes albopictus), they report in the journal PLoS Medicine.

The Pasteur Institute team analysed samples of the virus taken from 121 patients in Réunion, Madagascar, Seychelles, Mayotte and Mauritius.

The outbreak of chikungunya began in Réunion in early 2005 but dramatically accelerated in December, leaving health workers mystified as to how this happened.

Eventually, around 258,000 people — a third of the island's population of 777,000 — fell sick with the disease, which also claimed 219 lives directly or indirectly, according to the latest official toll.

The French scientists say the mutated form appears to have emerged in September 2005 and within a few months swiftly became the dominant viral strain in the epidemic.

Work is now underway to see whether another mutation, found in a sample taken from a Réunion woman with meningitis, also made the virus more destructive.

They add that DNA sequencing of six viral strains shows its historic link to viruses detected in eastern, central and southern Africa between 1952 and 2000.

"The viruses that emerged in the Indian Ocean islands have thus probably been imported from the African continent" by the movement of people, the researchers said in a statement.

The disease gets its name from a Swahili word meaning "that which bends up" because of its arthritic-type symptoms that leave victims stooped. Most patients eventually recover.

The French government has committed emergency health and economic aid worth over EUR 90 million to help Réunion, administered as an overseas department of France.

Around 6,000 other cases of illness have been recorded in Madagascar, Seychelles, Mauritius and Mayotte, which is a French dependency.

Copyright AFP

Subject: French news

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