Chikungunya Fever on the Island of Réunion

An outbreak of Chikungunya fever, a viral infection carried by mosquitoes, Aedes aegypti affected many countries of the Indian Ocean Basin from Spring 2005 onwards.  The most profoundly affected area has been the French island of Réunion; French Authorities estimated that in excess of a quarter of a million of the islands 750,000 inhabitants had been affected within 12 months of the onset of the outbreak. In addition, more than 300 cases had been imported to Metropolitan France and as many as 100,000 people were affected in India. 

Chikungunya fever is commonly found in East Africa, Southeast Asia and in the Indian sub-continent.  Illness generally follows 4-7 days after the bite of an infected mosquito and presents with sudden onset of fever with joint and muscle pain (that can at times be very severe) with headache and conjunctivitis. The joints of the wrists, ankles, hands and feet are most commonly affected. Rashes on the chest and abdomen are common and in the current outbreak on Réunion almost a quarter of patients had bleeding from the nose or gums. Fortunately, it tends to be a mild illness with most patients recovering fully, although there have been as many as 300 deaths reported in all affected countries, many in elderly patients with co-existing medical conditions. 

Additionally, there has been a laboratory confirmed case of Chikungunya fever in a nurse in France who became infected after taking a blood sample from an acutely ill patient. Despite this, the European Centre for Disease Prevention and Control (ECDC) considers the likelihood of introduction of the virus to Europe through the importation of infected vectors, or contamination through breach of universal precautions when handling blood samples or through blood transfusions, to be low.

There is currently no vaccine against the virus responsible for causing Chikungunya. Travellers to affected areas are advised to take sensible precautions against mosquito bites (advice on protecting yourself from mosquito can be found on HPSC's website http://www.hpsc.ie/hpsc/A-Z/Vectorborne/TravelAdviceforInternationalTravellers). In addition, the particular mosquito responsible for this outbreak had a tendency to appear during daylight hours so precautions should be used throughout daylight hours as well.

Although the risk of serious disease is low, certain groups are at higher risk, including:

• Pregnant women
• People with weakened immune systems (such as patients living with cancer or HIV/AIDS) and
• People suffering from severe chronic illness (such as heart, lung or kidney disease and diabetes).

Prevention: Given the high transmission pattern at this time of the year, it is advised that pregnant women, patients with weakened immune systems and people suffering from severe chronic illness should consult their physicians prior to the travel in order to assess their risk and obtain advice on personal preventive measures.

All travellers to these countries should take the following preventive measures to minimise the exposure to mosquito bites while in the areas:

• Use of anti-mosquito devices (insecticide-treated bed nets, coils, smudge pots, spray, repellents) and wearing long sleeve - long leg clothes, especially during the hours of highest mosquito activity (morning and late afternoon). Mosquito repellent based on a 30% DEET concentration is recommended.
• Before using repellents, pregnant women and children under the age of 12 years should consult a physician or pharmacist
• For newborn children under three months, repellents are not recommended; instead, insecticide-treated bed nets should be used.

Further up to date information for travellers can be found on the website of the European Centre for Disease Prevention and Control at http://www.ecdc.eu.int/outbreaks/Chikungunya_reunion.php.