27 October 2006

 

Chikungunya virus - India

In March 2006 the World Health Organization (WHO) reported an outbreak of chikungunya virus (CHIKV) infection and sporadic cases of dengue fever in the state of Andhra Pradesh and an outbreak of CHIKV in Maharashtra [1]. 

As of 25 October 2006, the Ministry of Health and Welfare of India have reported CHIKV outbreaks in 12 states [2]. More than 1.36 million suspected cases have been reported, with the most affected states, Karnataka and Maharashtra, reporting 758,531 and 263,268 suspected cases respectively. Cases have also been reported from the states of Andhra Pradesh, Delhi, Goa, Gujarat, Kerala, Madhya Pradesh, Pondicherry, Rajasthan, Tamil Nadu and the Andaman and Nicobar Islands.

Laboratory analysis has confirmed CHIKV infection in 12% of the 14,418 samples from suspected cases that have been tested. Although 4,469 suspected cases of CHIKV have been reported on the Andaman and Nicobar Islands, as yet none of these cases have been laboratory confirmed [2]. Deaths associated with CHIKV infection were reported in Alappuzha district in Kerala, however when these were investigated it was concluded that the deaths were likely to be due to other causes [3]. No deaths due to CHIKV have been reported during these outbreaks [2].

The Indian Government have reported a decrease in suspected cases of chikungunya between June and October 2006 [4], although between 28 August and 1 October 2006 the number of suspected cases of CHIKV reported weekly has increased in Kerala [5] and new foci of disease have been reported in other states.

At present, there is also an on-going dengue fever epidemic in India. As of 25 October 2006, 7,764 cases of dengue have been reported from the states of Andhra Pradesh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Maharashtra, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh and West Bengal [6]. CHIKV infection and dengue fever are clinically similar. However, unlike dengue fever, there is no haemorrhagic form of CHIKV and infection is usually self-limiting and very rarely fatal [7]. In areas with both CHIKV and dengue fever outbreaks it may be difficult to distinguish between these two infections on a clinical basis.

Advice for travellers

Information about CHIKV infection can be found in the NaTHNaC clinical update of 7 February 2006 [8]. For information about dengue fever, please see the NaTHNaC dengue health information sheet.

Both dengue fever and CHIKV are transmitted by mosquitoes and at present, there is no vaccine available to protect against these diseases. Travellers to affected areas are advised to take insect bite precautions, particularly during daylight hours when Aedes aegypti mosquitoes are active.

References

1. World Health Organization. Chikungunya and dengue in the south west Indian Ocean, 17 March 2006. Accessed 25 October 2006, available on line at:

http://www.who.int/csr/don/2006_03_17/en/index.html 

2. Ministry of Health and Welfare. Chikungunya fever situation in the country during 2006, 25 October 2006. Accessed 25 October 2006, available online at: http://www.namp.gov.in/Chikun-cases.html  

3. Ministry of Health and Welfare. Investigation of an outbreak of Chikungunya in district Alappuzha, Kerala, October 2006. Accessed 25 October 2006, available online at:http://www.namp.gov.in/Chikun-Invest.html

4. Ministry of Health and Welfare. Update on Chikungunya, 13 October 2006. Accessed 25 October 2006, available online at: http://www.namp.gov.in/Doc/Chikungunya%20-%20Update.pdf

5. Ministry of Health and Welfare. Chikungunya Trend, October 2006. Accessed 25 October 2006, available online at: http://www.namp.gov.in/Chikun-trend.html

6. Ministry of Health and Welfare. Press Release - Dengue, 25 October 2006. Accessed 25 October 2006, available online at: http://www.namp.gov.in/PressRelease.html  

7. Centre for Disease Control and Prevention. Outbreak Notice: Update: Chikungunya Fever India and the Indian Ocean Islands, 25 October 2006. Accessed 25 October 2006, available online at: http://www.cdc.gov/travel/other/2006/chikungunya_india.htm

7. NaTHNaC. Chikungunya virus - Réunion, Mauritius and Seychelles. 7 February 2006. Accessed 20 July 2006, available online at: http://www.NaTHNaC.org/pro/clinical_updates/chik_070206.htm

Links

Centre for Disease Control and Prevention. Chikungunya Virus Fact Sheet: http://www.cdc.gov/ncidod/dvbid/Chikungunya/CH_FactSheet.html