20 December 2006

Imported chikungunya virus in the United Kingdom - update

As of 31 October 2006, the Health Protection Agency’s Special Pathogens Reference Unit (HPA SPRU) has reported 106 cases of chikungunya infection [1]. Of these, 29 have been laboratory confirmed (by polymerase chain reaction [PCR] and/or virus isolation), 29 are probable cases (clinical symptoms and serologically positive [both IgG and IgM]), 33 are classified as suspected cases (clinical symptoms, relevant travel history and IgG positive), and 15 have had a past exposure (IgG positive with no clinical details or travel history, or IgG positive with history of past exposure).

Of the total, 67 cases reported travel to the Indian Ocean islands (57 to Mauritius, six to the Seychelles, and four to Madagascar), where a large outbreak was reported earlier in the year [2]. These cases were reported by the SPRU between 2 March and 31 August 2006, and the outbreak has since declined.

Twenty cases (received at SPRU between 30 May and 26 October 2006) reported recent travel to India, where an outbreak began in February 2006 [3]. Over a million suspected cases have been reported in India since the outbreak began, with 1867 cases confirmed. As of 19 December 2006, thirteen of the country's 31 states have been affected of which, Karnataka (298 confirmed, 762,026 suspected cases) and Maharashtra (774 confirmed, 268,321 suspected cases) have been most affected. Other states affected have been Andhra Pradesh, Tamil Nadu, Madhya Pradesh, Gujarat, Kerala, Orissa, Government of National Capital Territory of Delhi, Rajasthan, Pondicherry, Goa, and the Andaman and Nicobar Islands [4]. Further to this, an outbreak of suspected chikungunya has also been reported in Sri Lanka [5], although as of 31 October, no cases of chikungunya, related to travel to Sri Lanka, have been reported by the SPRU.

Advice for travellers

Nearly 800,000 United Kingdom residents travelled to India in 2005, a 21% increase compared to 2004 [6]. Although the chikungunya outbreak in India appears to be in decline [7], travellers to India and Sri Lanka should be aware of the risk of infection, which is transmitted by Aedes sp. mosquitoes (the same mosquito that transmits dengue fever, a disease which is also prevalent in India). Aedes mosquitoes are active during daylight hours (particularly around dusk and dawn) and prevention relies on insect bite avoidance.

Further information about chikungunya can be found in the NaTHNaC clinical update of 7 February or on the HPA website at: http://www.hpa.org.uk/infections/topics_az/Chikungunya/

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This update has been adapted from reference 1.

References

1. HPA. Imported chikungunya in the United Kingdom. Commun Dis Rep CDR Wkly 2006 [online]. [Accessed 19 December 2006]; 16 (50): news. Available at http://www.hpa.org.uk/cdr/archives/2006/cdr5006.pdf.

2. NaTHNaC. Chikungunya virus - update. 21 July 2006 [online]. [Accessed 19 December 2006]. Available at: http://www.NaTHNaC.org/pro/clinical_updates/chik_210706.htm

3. World Health Organization Epidemic and Pandemic Alert and Response (EPR) [online]. Chikungunya in India, 17 October 2006. [Accessed 19 December 2006]. Available at http://www.who.int/csr/don/2006_10_17/en/index.html.

4. National Vector Borne Disease Control Programme. Chikungunya fever situation in the country during 2006 (as on 19.12.2006) [online] [Accessed 19 December 2006]. Government of India Ministry of Health and Family Welfare. Available at http://www.namp.gov.in/Chikun-cases.html.

5. NaTHNaC. Suspected Chikungunya virus - Sri Lanka. Clinical update: 28 November 2006 [online]. [Accessed 19 December 2006]. Available at http://www.NaTHNaC.org/pro/clinical_updates/chik_281106.htm.

6. Office for National Statistics. The International Passenger Survey, Travelpac dataset 2005 [online]. London: ONS, 2006. Available at http://www.statistics.gov.uk/statbase/Product.asp?vlnk=14013.

7. Government of India, Ministry of Health and Family Welfare. Update on Chikungunya. 13 October 2006. [Accessed 19 December 2006]. Available at http://www.namp.gov.in/Doc/Chikungunya%20-%20Update.pdf.