INTRODUCTION:Chikungunya fever is a mosquito-borne viral disease with symptoms such as fever, joint pain, muscle pain, headache and nose and gum bleeding.
Chikungunya is endemic in parts of Africa, Southeast Asia and on the Indian sub-continent. In the summer of 2007 an outbreak of chikungunya started in the province of Ravenna in the Emilia-Romagna region of North-Eastern Italy. At the moment Ravenna is considered to be an area where transmission of chikungunya is taking place.
Infectious agent: The Chikungunya virus is an arbovirus (alphavirus of the family of 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, albopictus, polynesiensis). In La Réunion, where a large outbreak occurred in 2005-2006, the vecor was Aedes albopictus, a daytime vector with highest activity at the beginning and end of the day. This is also the suspected vector in the current Italian outbreak. 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. As from August 2007, an outbreak is reported in the province of Ravenna in the Emilia-Romagna region in Italy with local mosquito-borne transmission. If the local transmission is confirmed, it is the first time that Chikungunya virus is known to be transmitted by mosquitoes within Europe.
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:
- Use of anti-mosquito devices (insecticide-treated bed nets, spray, repellents) and wearing long sleeve – long leg clothes, especially during the hours of highest mosquito activity.
- 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 and protective clothing should be used.
- 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.
Other preventive measures: Measures at the community level include
- Reduction of mosquito breeding sites (removal of all open containers with stagnant water in and round houses, or, if that is not possible, treatment with larvicides)
- In affected areas, elimination of adult mosquitoes through aerial spraying with insecticides
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