Credit ECDC – Aedes Albopictus (Red & Yellow regions)
Although it isn’t the first time that local transmission of the Chikungunya virus has been reported in Europe, today’s World Health Organization DON (Disease Outbreak News) report of autochthonous transmission of this mosquito-borne virus Southeastern France is still noteworthy.
Chikungunya – until 2005 – was an obscure virus pretty much limited to causing small outbreaks in east central Africa, but a mutation in the envelope protein gene (E1-A226V) of the virus allowed Aedes Albopictus or `Asian tiger’ mosquito to transmit the virus more efficiently (see A Single Mutation in Chikungunya Virus Affects Vector Specificity and Epidemic Potential).
Armed with this new mutation, Chikungunya made a surprise jump to the Indian Ocean island of Réunion in 2005. There, it infected nearly 1/3rd of the island’s 770,000 residents (see 2006 EID article Chikungunya Disease Outbreak, Reunion Island) in just a matter of months, and from there spread into Asia and the South Pacific.
Chikungunya typically produces a fever, severe muscle and joint pain, and headaches. The symptoms usually go away after a few weeks, but some patients can sustain permanent disability, and some deaths have been reported.
Since the introduction of the virus into the Caribbean last winter it has spread rapidly, infecting hundreds of thousands of people in the tropical regions of The Americas. In June, the ECDC published - Chikungunya outbreak in Caribbean: Possible risk of local transmission in Europe in areas with mosquito species, vectors of the disease – which examined the likelihood of CHKV getting a foothold in Europe.
Today’s WHO report describes 4 locally acquired cases in Montpellier, France - after which, I’ll return with more.
Disease outbreak news
23 October 2014
On 21 October 2014, WHO was notified by the National IHR Focal Point for France of 4 cases of chikungunya locally-acquired infection in Montpellier, France. The cases were confirmed by tests conducted by the French National Reference Laboratory for arboviruses on 20 October 2014. This is the first time that locally-acquired transmission of chikungunya has been detected in France since 2010.
The 4 cases of chikungunya infection occurred within the same family, with symptoms onset between 20 September and 12 October. The cases live in Montpellier in the vicinity of a chikungunya case imported from Cameroon. The cases have no history of travel out of their district of residence in the 15 days prior to the onset of symptoms.
French public health authorities have implemented the following public health measures:
- Vector control aimed at preventing local transmission.
- Provision of information about the awareness of the cluster, the signs and symptoms of the disease, when and where to seek care, and how to prevent infection.
- Advice to health care practitioners on clinical case management.
- Assessment of the risk of infection through blood and tissues donations.
Chikungunya is a viral disease that is rarely fatal and is transmitted to humans by infected mosquitoes. Symptoms of chikungunya include high fever and headache, with significant pains in the joints (ankles, wrists), which can persist for several weeks. The symptoms appear between 4 and 7 days after the patient has been bitten by an infected mosquito. The name, chikungunya derives from a word in Makonde language roughly meaning “that which bends up”, reflecting the physique of a person suffering from the disease.
In 2010 France reported a pair of locally acquired CHKV cases (see EID Journal Chikungunya Virus, Southeastern France) in two children, one of whom had shared mosquito exposure with a child recently returned from India who was subsequently diagnosed as having CHKV.
The third child was presumably shared a mosquito vector with the second child.
Seven years ago a much larger outbreak was reported in Northern Italy. I described this outbreak in greater detail in It's A Smaller World After All, but the short version is that a traveler, returning from India, brought the virus to Italy in 2007 which led to more than 290 cases reported in the province of Ravenna, which is in northeast Italy.
While conditions are far from ideal for Chikungunya to entrench itself in most of Europe, the ECDC produced a map showing regions where – because of climate and the availability of the right mosquito vectors –conditions are `Rather suitable’ for the virus to thrive.
Although the impact of Chikungunya on North America has thus far been limited, this summer Florida has reported 11 locally acquired cases.