24 March 2006

 

Chikungunya update

 

La Réunion

As of the 17 March 2006, the sentinel network of 31 physicians based on La Réunion have reported 3,237 cases of chikungunya (CHIKV) since the outbreak began in March 2005. During the week of 6 to 12 March 2006, 84 cases of CHIKV were reported, less than in the previous week. The numbers of new cases reported per week has been declining since the peak during the week of 30 January to 5 February 2006 [1].

The number of people showing clinical symptoms of CHIKV infection on La Réunion since the epidemic began has been estimated as 212,000, with 5,600 of these infections occurring between 6 and 12 March 2006 [1].

An excess mortality of 35% was noted on La Réunion between 23 January and 26 February 2006 when compared with mortality rates in the same period of 2002, 2003 and 2004. In addition, 148 deaths on La Réunion have been recorded as associated with CHIKV infection since the outbreak began. Most of the deaths were in the elderly (median age 78) and further investigation is needed to determine the exact role of CHIKV infection in these deaths [1].

Other countries

Since the beginning of 2006 other countries in the south west Indian Ocean have reported cases of CHIKV. As of 5 March 2006 there have been around 6000 cases reported in Mauritius, of which 1200 have been laboratory confirmed. There have been 2,833 suspected cases on Mayotte between 9 January and 10 March 2006 and 8,818 suspected cases in the Seychelles as of 26 February 2006. Sporadic cases of CHIKV have also been reported in Madagascar in the city of Toamasina [2].

Several outbreaks of CHIKV have been reported in India since January 2006. In Andhra Pradesh 5671 cases of fever and arthralgia have been reported in an outbreak of CHIKV with sporadic cases of dengue fever. In Maharashtra state over 2000 cases of CHIKV have been reported between 1 and 15 March 2006 [2].

In February 2006 a WHO team were deployed to the islands of the south west Indian Ocean to assess the control measures that have been implemented on each island. The focus of the control measures is to reduce the mosquito breeding grounds together with an extensive public health education campaign. In India, as of 13 February 2006, a national team has been deployed to strengthen arbovirus surveillance and to improve clinical management of cases, vector control and social mobilization [2].

 

Imported cases

As of 31 January 2006 France has reported 160 cases of imported CHIKV infection in travellers returning from La Reunion and other islands in the south west Indian Ocean [3]. Germany, Switzerland, Italy and Norway have also reported imported cases [4]. There has also been an unofficial report of one imported case in French Guiana, in a woman who had travelled to Madagascar [5].

Four imported cases have been identified in England; two originating from the Seychelles and two from Mauritius [6].

Health professionals who evaluate returned travellers for suspected chikungunya virus infection can find information about submitting samples from potential cases at the HPA Special Pathogens Reference Unit website: http://www.hpa.org.uk/srmd/other_ref_labs/spru.htm 

Advice to travellers

Information about CHIKV infection can be found in the NaTHNaC clinical update of 7 February 2006 [7].

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

References

1. Institute de Veille Sanitaire. Epidemie de Chikungunya a La Reunion / Ocean Indien, Point de situation au 17 Mars 2006.

[cited 22 March 2006] Available at: http://www.invs.sante.fr/presse/2006/le_point_sur/chikungunya_

170306/index.html 2. World Health Organization. Chikungunya in La Reunion (France), Mayotte Maurice, Seychelles, and India, 17 March 2006 [cited 22 March 2006] Available at: http://www.who.int/csr/don/2006_03_17/en/index.html

3. Cases de Chikungunya importe en Metropole, Avril 2005 - Janvier 2006. 9 March 2006. [cited 22 March 2006] Available at: http://www.invs.sante.fr/presse/2006/le_point_sur/chikungunya_

cas_importes_090306/chikungunya_cas_importes_090306.pdf 4. Editorial Team, Pfeffer M, Löscher T. Cases of Chikungunya imported into Europe. Eurosurveillance Weekly, 2006; 11 (3). Available at: http://www.eurosurveillance.org/ew/2006/060316.asp#2

5. ProMED mail. Chikungunya - French Guiana EX Madagascar, 16 March 2006, [cited 22 March 2006] Available at: http://www.promedmail.org/pls/promed/f?p=2400:1001:1 1297629023117869368::NO::F2400_P1001_BACK_PAG E,F2400_P1001_PUB_MAIL_ID:1000,32352

6. Chikungunya outbreak in the Indian Ocean islands (and imported cases) - update. CDR Weekly. 16 (12), 23 March 2006. Serial online. Accessed 24 March 2006. Available at: http://www.hpa.org.uk/cdr/default.htm   

7. NaTHNaC. Chikungunya virus - Reunion, Mauritius and Seychelles. 7 February 2006. [Cited 22 March 2006] Available at: http://www.NaTHNaC.org/travel/news/chik1_070206.htm