Thursday, 25 June 2015

Chikungunya - don't be scared, but do know about it

Chikungunya virus and it's beautiful symmetry
In my previous blog post I discussed advancements towards a vaccine against Dengue virus. I’ve decided to keep with the topic of viral infections that, along with global warming, are now spreading out of the tropics and causing concern. The topic this time is Chikungunya virus. My hope for this post is to tell you a little about a virus you’ve probably never hear of, but if you take nothing else from it, you’ll at least be able to pronounce the name - chihk-uhn-guhn-yuh.

The habitable zone in which mosquitoes can survive is spreading because of global warming, and this is starting to pose some serious public health issues. Chikungunya was first described in 1952, and until recently, has been predominantly confined to Africa and parts of Asia. Yet as Aedes mosquitoes, the vector for the virus, spread, so too does the disease, which has now been found in the Americas and even parts of Southern Europe. Estimates suggest there have been over 3 million cases globally.

The virus is typically carried by the Aedes aegypti mosquito whose geographical range is restricted to the tropics. However, in 2005, a new strain of Chikungunya was found with a single mutation to one of the proteins exposed on the surface of the virus that allowed it to replicate efficiently in the closely related Aedes albopictus mosquito species. This mutation, and change of vector, was responsible for an outbreak on the island of RĂ©union, in the Indian Ocean, that caused around 266,000 cases (in a population of 800,000). A. albopictus can survive in more temperate conditions that A. aegypti, meaning this stain of the virus poses a real thread of widespread transmission. Indeed, this mutation is likely responsible for the emergence of cases in Southern Europe.

Global outbreaks of Chikungunya (

More recently Chikungunya has made its way to the Caribbean and the Americas, causing nearly 800,000 cases of disease across Caribbean islands last year. Fortunately, the virus that was transmitted across the Atlantic was not capable of spread in A. albopictus, which probably played a big part in limiting spread of infections to Florida and no further into the USA. However, the fact the virus is circulating causes concern; should mutations occur allowing spread in A. albopictus, much of North and South America will be at huge risk from endemic Chikungunya spread.

Chikungunya rarely causes fatal disease (probably explaining why not many people have heard of it), however, there are no current treatment options, nor a vaccine. While the infection may not be life threatening, that isn’t to say it’s pleasant. The disease begins like may viral diseases, causing the “flu-like” symptoms of fever, headache, chills etc. However, Chikungunya can also cause severe, even debilitating join pain, which can persist for months to years. Indeed, the name derives from a word in the Kimakonde language of East Africa meaning “to be contorted,” in reference to the appearance of infected individuals. Such symptoms can put real strain on working communities, and there are reports of whole towns coming to a stand-still because of bed-ridden Chikungunya sufferers.

Chikungunya is a virus that is currently sat on the brink of major global spread, yet I’m guessing most people have never heard of it. Should the virus currently found in central parts of the Americas mutate to spread in A. albopictus, a huge number of people will be at risk of a severely debilitating disease. It does seem that infection with Chikungunya can provide protection from re-infection, making the prospects of a vaccine promising. However, as was highlighted with the recent outbreak of Ebola, without proper forward planning, and funding, science is largely reactive; should Chikungunya spread really take off, I suspect we will not be ready for it. Even though it may not make the headlines as much as other viruses, research into understanding Chikungunya is necessary. Hopefully this blog has helped illustrate why it’s important to work on viruses other than those that always hit the headlines.

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