Chikungunya virus threatens to spread worldwide

[DB]

http://www.zeenews.com/znnew/articles.asp?rep=2&aid=297365&ssid=28&sid=ENV
New York, May 23: Scientists have found clues as to why a little-known virus is disabling hundreds of thousands of Indian ocean island dwellers, in an outbreak that threatens to spread further around the world, including in India.

It seems the virus has adopted a genetic change that may make it more efficient at invading the mosquitoes that carry it from person to person, 'Nature' magazine reported today.

The Chikungunya virus has infected around one-third of the population on the French Island of Riunion since early 2005. It has also hit the neighbouring islands of Mauritius, Seychelles, Madagascar and Mayotte, and reared its head in India, the report said.

The outbreak seems to be more severe than the sporadic occurrences of Chikungunya that have hit Africa and Asia in the past: It has spread like wildfire, infecting some people's nervous systems and even killing a fraction of its victims.

The fever strikes so fast that "You're driving your car and suddenly you have to stop", Sylvain Brisse of the Institute Pasteur in Paris, France, was quoted as saying.

Brisse and his colleagues have revealed some key aspects of the virus' genetic makeup that might explain its newfound ferocity.

The team worked out the genetic sequence of six samples of Chikungunya virus taken from patients throughout the current outbreak, and scrutinized one key coat protein from another 121 patients.

Bureau Report

 

[Snowy Owl]

Re: Chikungunya virus threatens to spread worldwide

Des chercheurs de l'Institut Pasteur ont pu retracer l'origine et l'?volution du virus chikungunya dans l'Oc?an indien gr?ce au s?quen?age complet du g?nome de six souches virales isol?es chez des malades ? La R?union et aux Seychelles, selon des travaux publi?s mardi.
Ils ont ?galement d?couvert une mutation sur un g?ne du virus ayant pu faciliter son adaptation au moustique Aedes albopictus qui n'?tait pas connu jusque l? pour ?tre un vecteur du virus chikungunya.
L'?tude montre que les souches virales de l'Oc?an indien sont proches entre elles et apparent?es aux souches de l'Afrique de l'Est, centrale et du Sud isol?es entre 1952 et 2000: "les virus ayant ?merg? dans les ?les de l'Oc?an indien ont donc vraisemblablement ?t? import?es depuis le continent africain", pr?cise l'Institut Pasteur dans un communiqu?.
"M?me si, ? notre connaissance, aucune ?pid?mie n'a ?t? signal?e r?cemment en Afrique de l'Est, ce sc?nario est compatible avec les ?changes de population entre l'Afrique de l'Est et les Comores, o? l'?pid?mie aurait commenc?", rel?vent Sylvain Brisse et Isabelle Schuffenecker qui ont coordonn? cette ?tude.
Outre le s?quen?age complet de six souches virales (dont trois pr?lev?es sur des malades d?but 2005 et les trois autres plus tard dans l'ann?e), les chercheurs ont effectu? celui d'un g?ne de virus provenant de 121 autres patients de La R?union, Madagascar et des ?les voisines (Seychelles, Maurice, Mayotte).
Ces travaux publi?s dans la revue scientifique d'acc?s gratuit PLoS Medicine ont notamment permis de mettre en ?vidence plusieurs mutations dans une souche virale pr?lev?e chez un R?unionnais atteint de m?ningo-enc?phalite. Des ?tudes sont en cours pour d?terminer si elles sont associ?es ? une plus grande virulence neurologique du virus.
Le s?quen?age du g?ne E1 correspondant ? une prot?ine impliqu?e dans l'attachement du virus aux membranes cellulaires du moustique a montr? l'apparition d'un nouveau g?notype (forme g?n?tique), en septembre 2005, devenu rapidement dominant.
Une des mutations du g?ne, survenue trois mois avant "l'augmentation spctaculaire" de l'?pid?mie en d?cembre 2005, pourrait, selon les chercheurs, avoir permis une adaptation du virus au moustique Aedes albopictus.
Depuis le d?but de l'?pid?mie en f?vrier-mars 2005, 258.000 cas de chikungunya ont ?t? recens?s ? La R?union, entra?nant 219 d?c?s directs et indirects en 2006, selon le dernier bilan hebdomadaire officiel datant du 18 mai.
Depuis janvier 2006, plus de 6.000 cas ont par ailleurs ?t? recens?s ? Mayotte, ainsi que, selon l'Institut de veille sanitaire, "plusieurs milliers de cas entre janvier et mars" aux Seychelles et ? l'?le Maurice et quelques cas aux Comores et ? Madagascar.

http://actu.voila.fr/Article/mmd--francais--journal_internet--medecine/060523080249.wfa3vti4.html

 

[Snowy Owl]

Re: Chikungunya virus threatens to spread worldwide

Babelfish translation

Researchers of Institut Pasteur could recall the origin and the evolution of the virus chikungunya in the Indian Ocean thanks to the complete sequencing of the genome of six viral strains isolated among patients with the Meeting and Seychelles, according to public works' Tuesday. They also discovered a change on a gene of the virus which has been able to facilitate its adaptation to the mosquito Aedes albopictus which was not known until being a vector of the virus chikungunya there. The study shows that the viral strains of the Indian Ocean are close between them and related with the stocks of the East Africa, power station and of the South insulated between 1952 and 2000: "the viruses having emerged in the islands of the Indian Ocean were thus probably imported from the African continent", specifies the Pasteur Institute in an official statement. "Even if, to our knowledge, no epidemic were announced recently in East Africa, this scenario is compatible with the exchanges of population between the East Africa and the Comoros, where the epidemic would have started", raise Sylvain Brisse and Isabelle Schuffenecker who coordinated this study. In addition to the complete sequencing of six viral strains (of which three taken on patients at the beginning of 2005 and the three others later in the year), the researchers carried out that of a gene of virus coming from 121 other patients of the Meeting, Madagascar and of the close islands (Seychelles, Maurice, Mayotte). These public works in the scientific review of free access PLoS Medicine in particular made it possible to highlight several changes in a viral strain taken at R?unionnais reached of meningoencephalitis. Studies are in hand to determine if they are associated a greater neurological virulence of the virus. The sequencing of the E1 gene corresponding to a protein implied in the attachment of the virus to the cellular membranes of the mosquito showed the appearance of a new genotype (genetic form), in September 2005, became quickly dominating. One of the changes of gene, occurred three months before "the increase spctaculaire" of the epidemic in December 2005, could, according to researchers', to have allowed an adaptation of the virus the mosquito Aedes albopictus. Since the beginning of the epidemic in February-March 2005, 258.000 cases of chikungunya were listed with the Meeting, involving 219 direct and indirect deaths in 2006, according to the last official weekly assessment dating from May 18. Since January 2006, more than 6.000 cases were in addition listed in Mayotte, like, according to the Institute of medical day before, "several thousands of case between January and March" in Seychelles and Mauritius and some cases in the Comoros and Madagascar.

 

[DB]

Re: Chikungunya virus threatens to spread worldwide

http://www.todayonline.com/articles/120065print.asp

French researchers said an epidemic of the disease known as chikungunya, which ravaged the Indian Ocean island of Reunion, 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 Reunion, Madagascar, Seychelles, Mayotte and Mauritius.

The outbreak of chikungunya began in Reunion 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 Reunion 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 90 million euros (110 million dollars) to help Reunion, 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. ? AFP

 

[DB]

Re: Chikungunya virus threatens to spread worldwide

This may explain some of what is going on in the French Islands.

What about India?

How did India explode at exactly the same time as La Reunion?

There are currently over 1 million cases in India, probably somewhere around 5-10 million cases as of this writing.

Is the situation in India also due to the Asian tiger mosquito, or could there be another vector or could the virus mutated once again to provide it the ability to spread via water or air?

It is not very comforting that it took 6 months for them to figure out that one gene E1 had changed.

If this is any indication of how long it takes for scientists to recongnize a change in a viruses genome then we will not have the ability to create a vaccine for first responders to a H5N1 pandemic.

Six months is not acceptable.