Travel Health Advisory

Outbreak of Chikungunya Virus on the French Island Territory of Réunion

The Public Health Agency of Canada is monitoring a significant ongoing outbreak of chikungunya virus - a mosquito-borne disease - on the French Island territory of Réunion, located in the south western region of the Indian Ocean. Between March 28, 2005 and January 8, 2006 a total of 7138 cases of chikungunya infection were reported through Réunion's surveillance system. Of these cases, 2147 or 30% were confirmed by laboratory analysis.

In early 2005, a large outbreak of chikungyuya occurred in the Comoros islands located off the east coast of Africa. From there, the virus circulated to other islands in the Indian Ocean and cases have been reported in Mayotte, Mauritius, Seychelles and Réunion. Réunion had not recorded a single case of the virus prior to this outbreak.

As of January 2006, transmission activity continues to occur and cases are being reported on the islands of Mauritius, Seychelles, Mayotte and Réunion.

French health authorities are collaborating closely with local authorities and medical practitioners to control the outbreak. Intensive measures to interrupt transmission, including increased surveillance and mosquito-control measures, continue to be implemented.

Source: Eurosurveillance, Institut de veille sanitaire (France)

Chikungunya virus is most commonly transmitted to humans through the bite of an infected mosquito, specifically mosquitoes of the Aedes genus, which usually bite during daylight hours.

Symptoms of infection, which generally last three to seven days, include the sudden onset of fever, chills, headache, nausea, vomiting, severe joint pain (arthralgias) and rash. Although rare, the infection can result in meningoencephalitis (swelling of the brain), especially in newborns and those with pre-existing medical conditions. Pregnant women can pass the virus to their fetus. Residual arthritis, with morning stiffness, swelling, and pain on movement, may persist for weeks or months after recovery. Severe cases of chikungunya can occur in the elderly, in the very young (newborns), and in those who are immunocompromised. Chikungunya outbreaks typically result in several hundreds or thousands of cases but deaths are rarely encountered.

Chikungunya virus is most likely of African origin. Recent outbreaks have occurred in Sub-Saharan Africa, India, South-east Asia, and the Philippines.

There is no vaccine that protects against chikungunya virus. Treatment for chikungunya typically involves treating the symptoms and includes bed-rest and the use of non-aspirin analgesics during the phase of illness where the symptoms are most severe. Using protective measures to prevent being bitten by an infected mosquito remains the only means to reduce the risk of exposure.

Recommendations

The Public Health Agency of Canada reminds travellers to tropical and subtropical areas of the world that they may be at risk for contracting mosquito-borne diseases, such as malaria, dengue, Japanese encephalitis, yellow fever, and other less common diseases like chikungunya. Travellers are strongly encouraged to consult their personal physician or a travel medicine practitioner to discuss their individual risk of exposure to such diseases.

The Public Health Agency of Canada strongly recommends that travellers take the following personal precautions to reduce the risk of exposure to mosquitoes:

• remain in well-screened or completely enclosed, air-conditioned areas;
• wear light-coloured clothing with full-length pant legs and sleeves; and
• use insect repellent on exposed skin.

The use of insect repellent on exposed skin is strongly recommended. Of the insect repellents registered in Canada, those containing 'N, N diethyl-m-toluamide' (DEET) are the most effective. There are specific things you should know about DEET, especially regarding its use on young children.

Although the concentration of DEET varies from product to product, repellency rates are largely equivalent. In general, higher concentrations protect for longer periods of time, but there is little advantage in the duration of repellence with DEET concentrations greater than 50%, and there may be additional risk of toxicity with higher concentrations. New micro-encapsulated products containing 33% DEET are registered in Canada, and they should provide up to eight hours of protection.

Children and DEET

In rare instances, application of insect repellents with DEET has been associated with seizures in young children (only 14 cases over 30 years of DEET use and billions of applications every year). The actual concentration of DEET varies among repellents and can be as high as 95%. However, repellents with DEET concentrations of 10% are very effective and should last three to four hours. Therefore, for children, DEET in a concentration of 10% or less should be applied sparingly to exposed surfaces only and washed off after children come indoors. The likelihood of adverse reactions can be minimized by the following precautions:

• apply repellent sparingly and only to exposed skin;
• avoid applying high concentration products;
• avoid applying repellents to portions of children's hands that are likely to contact the eyes or mouth;
• never use repellents on wounds or irritated skin; and
• wash repellent-treated skin after children come indoors. If a reaction to insect repellent is suspected, wash treated skin and seek medical attention.

In Canada, DEET products are not recommended for use in children less than two years of age. More information on insecticide use in Canada.

The Public Health Agency of Canada's Committee to Advise on Tropical Medicine and Travel (CATMAT) produces evidence based statements and guidelines. For additional information on Arthropod Bite Prevention.

As a reminder...

The Public Health Agency of Canada routinely recommends that Canadian international travellers consult their personal physician or a travel clinic prior to international travel, regardless of destination, for an individual risk assessment to determine their individual health risks and their need for vaccination, preventative medication, and personal protective measures.

The Public Health Agency of Canada recommends, as well, that travellers who become sick or feel unwell on their return to Canada should seek a medical assessment with their personal physician. Travellers should inform their physician, without being asked, that they have been travelling or living outside of Canada, and where they have been.

Additional information from the Public Health Agency of Canada:

• More information about arthropod bite prevention.
• More information about malaria.
• More information about dengue
• For information about yellow fever.

Released: February 10, 2006

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