16 November 2007

Chikungunya virus infection in Italy – update

In August 2007 an outbreak of chikungunya virus infection (CHIKV) was identified in the District of Ravenna, Emilia Romagna region of Italy [1-3]. In September upon invitation of the Ministry of Health of Italy, representatives from the European Centre for Disease Control (ECDC) and the World Health Organization (WHO) visited the area of the outbreak. Their goals were assessing the risk of establishment and spread of CHIKV in the EU; exploring the potential implications for the EU and other European countries and advising Italian authorities on investigation and control issues. The report of this visit has been recently published [3].

As of 21 September 2007, a total of 292 cases of suspected CHIKV infection were identified in Emilia Romagna region of Italy [3]. CHIKV infection was confirmed in 125 of the cases. Epidemiological data indicated that limited indigenous transmission occurred in localities outside of the original two affected villages of Castiglione di Ravenna and Castiglione di Cervia. It was expected that cases would continue to be reported through the month of October until mosquito activity declined. Extensive vector control efforts were implemented.

The main findings from the ECDC and WHO visit included:

• Evidence for indigenous transmission of CHIKV in at least three areas beyond the initial two villages.
• Aedes albopictus mosquitoes, the main vector of CHIKV infection, were well established in the affected areas.
• The presence of Aedes in other areas of continental Europe presents the possibility of introduction and establishment of local transmission foci of CHIKV where the mosquito is present.
• Reappearance of CHIKV in the affected area in the spring of 2008 could occur through persistence of adult mosquitoes through the winter months or theoretically through trans-ovarial passage of virus.
• Continued study for the presence of Aedes in Europe is needed as well as vector monitoring and control activities.
• Early detection of imported or indigenous cases of CHIKV infection is needed.

Advice for travellers

CHIKV is a mosquito borne viral infection and is endemic to large parts of Africa, the Middle East, India, and South East Asia. A large epidemic of CHIKV infection occurred in the islands of the Indian Ocean in 2005 and 2006 [4], and cases have been ongoing in India [5].

Initial symptoms of CHIKV infection include a sudden onset of severe arthralgias and myalgias, accompanied by fever, headache and conjunctivitis, and rash. Illness usually resolves over three to five days. Most patients recover fully over a period of a few weeks.

There is no vaccine available to protect against CHIKV infection. Travellers to affected areas are advised to take insect bite precautions, particularly during daylight hours when Aedes mosquitoes are active.

The mosquito vector for CHIKV infection does not exist in the United Kingdom (UK). Health professionals who see travellers with a compatible illness within 12 days of return from an affected area should consider the diagnosis of CHIKV infection [6,7].

References

1. World Health Organization Regional Office for Europe. Chikungunya in Emilia Romagna Region, Italy. Update: 16 September 2007. [Accessed 16November 2007]. Available at http://www.euro.who.int/surveillance/outbreaks/20070904_1

2. NaTHNaC. Chikungunya virus infection in Italy, Ravenna District. News, 3 September 2007. On-line resource, accessed 16 November 2007. Available at http://www.nathnac.org/travel/news/chikungunya_030907.htm

3. European Centre for Disease Prevention and Control. Mission Report Chikungunya in Italy. Joint ECDC/WHO visit for a European risk assessment 17 – 21 September 2007. [Accessed 16 November 2007]. Available at http://www.ecdc.eu.int/

4. NaTHNaC. Chikungunya virus – update. Clinical Update, 21 July 2006. On-line resource, accessed 16 November 2007. Available at http://www.nathnac.org/pro/clinical_updates/chik_210706.htm

5. International and Tropical Department, Health Surveillance Institute (DIT-InVS), France. India: Chikungunya. Weekly International Bulletin No. 103, 6–12 Sep 2007. On-line resource, accessed 16 November  2007. Available at: http://www.invs.sante.fr/international/bhi/bhi_120907.pdf

6. NaTHNaC. Imported chikungunya virus in the United Kingdom, 2006. News 12 April 2007. On-line resource, accessed 16 November  2007. Available at: http://www.nathnac.org/travel/news/chik_UK120407.htm

7.  Health Protection Agency.  Imported chikungunya virus in the United Kingdom, 2006. Health Protection Report. 1(15) 13 April 2007. On-line resource, accessed 16 November 2007, Available at: http://www.hpa.org.uk/hpr/archives/2007/hpr1507.pdf

Links

Health Protection Agency. Chikungunya. On-line resource. Available at: http://www.hpa.org.uk/infections/topics_az/Chikungunya/ default.htm

United States Centers for Disease Control and Prevention. Chikungunya Virus Fact Sheet: http://www.cdc.gov/ncidod/dvbid/Chikungunya/chickvfact.htm

European Centre for Disease Prevention and Control http://www.ecdc.eu.int/index.html

NaTHNaC Outbreak Surveillance Search

http://www.nathnac.org/countrysearch.aspx