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News Archives 9 March 2006

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Archives | News Archives 2006: Page 1| News 9 March 2006

News Archives: | 2006 | 2005 | 2004 | 2003

• Composition of the 2006/07 Influenza Vaccine
• Chikungunya virus in the Indian Ocean – update

Composition of the 2006/07 Influenza Vaccine

WHO has recommended that the 2006/07 trivalent influenza vaccine for the northern hemisphere winter contains:

• an A/New Caledonia/20/99(H1N1)-like virus;
• an A/Wisconsin/67/2005 (H3N2)-like virus*;
• a B/Malaysia/2506/2004-like virus†

Candidate vaccine viruses include:

* A/Wisconsin/67/2005 (H3N2) and A/Hiroshima/52/2005
† B/Malaysia/2506/2004 virus and B/Ohio/1/2005

This annual review of vaccine composition is necessary to match the vaccine with the changing viruses that are predicted to circulate during the 2006/07 season, if the normal pattern of seasonal influenza continues. WHO bases its annual vaccine composition recommendation on those influenza viruses isolated and characterised by WHO/National Influenza Centres, which are located in more than 80 countries. Along with this recommendation, WHO also provides the vaccine manufacturing industry with prototype strains for the seasonal vaccine and materials to ensure that global vaccine standards are met.

Chikungunya virus in the Indian Ocean – update

Outbreaks of chikungunya virus that have been occurring on some islands of the Indian Ocean since March 2005 are ongoing (1). The majority of cases have occurred since the beginning 2006, the largest outbreak of which has occurred in La Réunion; outbreaks have also been occurring in Mauritius, The Seychelles, Mayotte, and more recently, Madagascar.

La Réunion
Between 28 March 2005 and 26 February 2006, 2,849 cases of chikungunya virus have been reported by 31 physicians from a general practitioner (GP) sentinel network in La Réunion, which includes 288 cases reported between 20 and 26 February 2006 (2). A mathematical model has estimated that 186,000 people (20% of the population) may have been infected in total between March 2005 and 26 February 2006, including 19,000 between 20 and 26 February. More than 140,000 of these cases are estimated to have occurred since 1 January 2006. Virtually the whole island has now been affected.

The estimated attack rate by age group based on the GP notifications indicates the rate of infection has been greater in older people compared to younger (3.8% in those aged 65 years and over compared with 1% in those aged under 30 years) (3).There have been 77 deaths recorded with chikungunya as a diagnosis; the mean age of these deceased patients was 78 years, and most had underlying medical conditions. The possible relation between chikungunya and death is still under investigation by a scientific committee with clinicians, epidemiologists and virologists (3).

Other islands
Table 1 shows the number of cases reported from the other islands affected between 1 January and 1 March 2006 (4). There have also been reports in the media of cases occurring in Madagascar, although no case numbers have been released (5, 6).

Table 1 Cases reported from other islands in the Indian Ocean: 1 January to 1 March 2006

The World Health Organization has a team working in the region to assist with vector control and surveillance (4).

Imported cases
Between 9 April 05 and 31 Jan 2006, 160 cases of imported chikungunya virus were imported into metropolitan France (7). Imported cases have also been reported in Germany and Switzerland (8). The responsible vector, Aedes albopictus, has previously been identified in some limited places in southern France, but is extremely uncommon in Germany and Switzerland, so the risk of onward transmission in these countries is low. The risk of autochthonous transmission from imported cases in France is to be evaluated before the summer of 2006 (3).

It is possible that a few cases may be imported into the United Kingdom (UK) as the UK holiday season approaches and the Seychelles and Mauritius are popular tourist destinations with UK travellers (1). The mosquito vector has not, however, been found in the UK (9) and so the risk for ongoing transmission from imported cases is extremely low.

There are currently no restrictions on travel to islands in the Indian Ocean. Travellers to affected areas are advised to take insect bite precautions (fact sheet available from the National Travel Health Network and Centre, www.nathnac.org/pro/factsheets/iba.htm), particularly during daylight hours when the vector mosquitoes are active.

References

1. HPA. Chikungunya virus in the Indian Ocean. Commun Dis Rep CDR Wkly [serial online] 2006 [cited 9 March 2006]; 16(9): News. Available at <http://www.hpa.org.uk/cdr/archives/archive06/News/news0606.htm#chik>.

2. Institute de Veille Sanitaire. Epidemie de chikungunya a La Réunion / Ocean Indien, Point de situation au 3 Mars 2006 [online]. [cited 9 March 2006]. Available at: <http://www.invs.sante.fr/display/?doc=presse/2006/le_point_sur/chikungunya_030306/index.html>.

3. Cordel H. Chikungunya outbreak on Reunion: update. Eurosurveillance Weekly [serial online] 2 March 2006 [cited 9 March 2006]; 11(3). Available at: <http://www.eurosurveillance.org/ew/2006/060302.asp#3>.

4. World Health Organization. Chikungunya in Mauritius, Seychelles, Mayotte (France) and La Réunion island (France) – update [online] 1 March 2006. [accessed 9 March 2006]
Available at: <http://www.who.int/csr/don/2006_03_01/en/index.html>.

5. BBC News. Madagascar hit by mosquito virus [online] 6 March 2006. [accessed 9 March 2006]. Available at <http://news.bbc.co.uk/2/hi/africa/4777530.stm>.

6. Reliefweb. Madagascar: chikungunya virus confirmed [online] 6 March 2006. [accessed 9 March 2006]. Available at <http://www.reliefweb.int/rw/RWB.NSF/db900SID/DPAS-6MNCQW?OpenDocument>.

7. Cas de Chikungunya importés en Métropole avril 2005-janvier 2006. Paris: Institute de Veille Sanitaire, 2006. [accessed 9 March 2006].Available at <http://www.invs.sante.fr/presse/2006/le_point_sur/ chikungunya_cas_importes_090306/chikungunya_cas_importes_090306.pdf>.

8. ProMED-mail. Chikungunya - Indian Ocean update (05): spread to Europe [online] 4 March 2006. Archive no: 20060304.0695. [accessed 9 March 2006]. Available at <http://www.promedmail.org/>.

9. Medlock JM, Snow KR, Leach S. Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors. Med Vet Entomology 2005; 19: 2-21.