Latest update: 28 November 2007
Infectious agent: The Chikungunya virus is an arbovirus (alphavirus of the family Togaviridae); this is a heat-sensitive RNA virus. The virus was first isolated in Tanzania and Uganda in 1953. The name origins from the posture of the patients: in Makonde language, chikungunya means: « that which bends up ».
Reservoir: The main virus reservoirs are monkeys, but other species can also be affected, including humans.
Transmission modes: In urban areas (where most of the outbreaks have been reported in Asia), the disease is transmitted from human to human by Aedes mosquitoes (Aedes aegypti, Aedes albopictus, Aedes polynesiensis). In La Réunion, where a large outbreak occurred in 2005-2006, the vector was Aedes albopictus, a daytime vector with highest activity at the beginning and end of the day. This was also the vector in the Italian outbreak in 2007. Among monkeys, the disease is transmitted by Aedes furcifer and africanus.
Clinical presentation: Incubation ranges from 1 to 12 days, with an average of 4 to 7 days. The main clinical symptoms in patients are fever, joint pain, muscle pain and headache. Benign haemorrhagic symptoms, such as bleeding from the nose or gums, are possible, in particular in children. While most of the cases recover without consequences, the development of a more chronic phase is possible, with persistent joint pains. Recovery may take several weeks for these patients, coinciding with pronounced lethargy. During the outbreak in La Réunion, severe complications have been described, including respiratory failure, cardio-vascular decompensation, or meningo-encephalitis.
Epidemiology: Chikungunya is endemic in parts of Africa, Southeast Asia and on the Indian sub-continent. In Africa, cases have been described between 1957 and 1974 in Transvaal, Uganda, Congo, Nigeria, Ghana, and South Rhodesia (now Zimbabwe). Serologic studies have also shown the virus in Senegal, Burkina Faso, the Central African Republic, Cameroon, and Guinea-Bissau. More recently, the virus was documented in Asia, in particular in the Philippines, Malaysia, Cambodia, southern India and Pakistan. In 2005-06, a major outbreak affected several islands in the Indian Ocean, moving from the Comoro Islands, to other islands in the Indian Ocean, Mauritius, Mayotte, Madagascar, Seychelles and La Réunion, an overseas department of France. In La Réunion, a total of 266 000 cases were reported, with 254 deaths, mostly occurring in elderly patients with an underlying medical condition. In 2006, other countries reporting outbreaks of chikungunya included India, Sri Lanka, The Maldives, Malaysia and Indonesia. During this period, imported cases of chikungunya among tourists were reported in several European countries.
Areas of Chikungunya virus transmission in 2007: In 2007, apart from an outbreak in Gabon in the beginning of the year, and cases reported from Indonesia and Madagascar, the majority of the chikungunya cases were mostly being reported from India. From August to October 2007, an outbreak occurred in the province of Ravenna in the Emilia-Romagna region in North-Eastern Italy. This was the first reported outbreak of autochthonously transmitted Chikungunya virus in Europe with 214 confirmed cases. Although, due to appropriate control measures and the start of the winter season, this outbreak was limited in space and time, the possibility of new cycles of Chikungunya virus transmission remain next spring.
Treatment: Symptomatic only (non-steroid anti-inflammatories, non-salicylic analgetics).
Information to visitors to areas of transmission: pregnant women, immuno-deprived people and people suffering from a severe chronic illness should consult their physicians prior to the travel in order to assess their risk and get recommendations on personal preventive measures.
All travellers to the countries where chikungunya fever is occurring should take the following preventive measures to minimise the exposure to mosquito bites while in the areas:
Other preventive measures: Measures at the community level include
Acknowledgement: For more information on avoiding mosquito bites, refer to http://www.nathnac.org/pro/factsheets/iba.htm published by the National Travel Health Network and Centre, NaTHNaC, in the UK. This fact sheet is based on information from the Institut de Veille Sanitaire, Saint Maurice, France.
Links:
Consultation on chikungunya risk assessment for Europe:
http://www.ecdc.europa.eu/Health_topics/Chikungunya_Fever/Chikungunya_Fever.html
Chikungunya fact sheet by the European Network for Diagnostics of Imported Viral Diseases (ENIVD):
http://www.enivd.de/VHFDISEASES/fs_vhfdiseases.htm
Chikungunya in north-eastern Italy: a summing up of the outbreak.
http://www.eurosurveillance.org/ew/2007/071122.asp#2
Resurgence of chikungunya virus in India: an emerging threat:
http://www.eurosurveillance.org/ew/2006/060810.asp#2
Chikungunya risk assessment in Europe: recommendations for action:
http://www.eurosurveillance.org/ew/2006/060511.asp#2
Imported cases of chikungunya in metropolitan France – update to June 2006:
http://www.eurosurveillance.org/ew/2006/060824.asp#1
Chikungunya outbreak in Réunion, a French ‘overseas département’:
http://www.eurosurveillance.org/ew/2006/060202.asp
E-alert 27 January: Chikungunya outbreak in Réunion, a French ‘overseas département’:
http://www.eurosurveillance.org/ew/2006/060126.asp
