7 February 2006

 

Chikungunya virus - Reunion, Mauritius and Seychelles

 

Reunion

An epidemic of chikungunya virus (CHIKV) began on Reunion in late March 2005, with over 3,000 cases reported between 28 March 2005 and 10 July 2005 [1]. It is likely that the first cases were imported from the Comoros archipelago.

From mid-July, 2005, the number of cases in Reunion declined, but in mid-December cases numbers began to rise [2]. By 18 January 2006 there were an estimated 1,200 new cases occurring each week [3]. Cases have been reported in all of the districts on Reunion, with the district of Saint-Pierre being most heavily affected, particularly in the city of Saint-Louis [4]. Between 28 March 2005 and 3 February 2006, 2,636 cases of have been laboratory confirmed [1]. Mathematical models have suggested that since the beginning of the epidemic around 30,000 [4] to 50,000 [1] people may have exhibited symptoms compatible with CHIKV infection.

On the 5 February 2006 the first ever death attributable to CHIKV was reported on Reunion [5].

Since the end of the 2005 winter season, in October, vector control measures have been stepped up [1]. Military personnel have been deployed to aid in the vector eradication campaign [7] and the need for the community to practice bite avoidance measures and rid their properties of mosquito breeding sites has been emphasized [1]. 

 

Mauritius

During January 2006, 15 cases of chikungunya infection were reported in Mauritius. Although the majority of these cases had a history of recent travel to Reunion, since the 23 January 2006 cases without any travel history have been reported. The government has set up an advisory committee to decide what preventative measures should be taken and are purchasing equipment for mosquito eradication [6].  

Seychelles

CHIKV infection was reported in November 2005. Since then the number of new cases have been increasing with 2,000 cases reported during January 2006. The national armed forces have been deployed to aid in mosquito eradication efforts [7].

Chikungunya virus infection [8, 9]

Chikungunya virus is a member of the Alphavirus genus, and was first identified in humans during an epidemic in Tanzania in 1952 - 1953. The virus is endemic to large parts of Africa, the Middle East, India and south-east Asia.

The main vector to humans is Aedes aegypti mosquitoes. Infection may be transmitted between humans in urban areas and between primates in a sylvatic cycle. Introduction of CHIKV into populated areas often results in large epidemics.

The incubation period of CHIKV is between two and 10 days, with an average of two to four days. Initial symptoms include a sudden onset of severe arthralgias and myalgias, accompanied by fever, headache and conjunctivitis. Joint involvement is usually symmetrical, affects the extremities and can result in periarticular swelling, pain, redness and limitation of movement. A maculopapular rash involving primarily the trunk can occur concurrently with defervescence. Illness usually resolves over three to five days, but may be biphasic.

Most patients recover fully over a period of a few weeks, although 5 - 10% of patients will experience chronic joint pain, stiffness and swelling that can persist for a year or more.

Advice to travellers

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 Aedes aegypti mosquitoes are active.

 

References

1. Institute de veille sanitaire, Epidémie de Chikungunya à La Réunion / Océan Indien. 3 February 2006, Available on line at: http://www.invs.sante.fr/display/?doc=presse/2006/

le_point_sur/chikungunya_030206/index.html

2. ProMED-mail, Chikungunya - Mauritius and Reunion island (04): Reunion, 31 December 2005; 20051231.3716. Available on line at: http://www.promedmail.org/pls/promed/f?p=2400:10

01:12364583969454175288::::F2400_P1001_BACK_P

AGE,F2400_P1001_ARCHIVE_NUMBER,F2400_P1001_

USE_ARCHIVE:1001,20051231.3716,Y

3. ProMED-mail, Chikungunya - Mauritius and Reunion island (02): Reunion, 21 January 2006; 20060121.0202. Available on line at:

http://www.promedmail.org/pls/promed/f?p=2400:10

01:7354607149207892102::NO::F2400_P1001_BACK

_PAGE,F2400_P1001_PUB_MAIL_ID:1010,31713

4. Chikungunya outbreak in Réunion, a French ‘overseas département’, Eurosurveillance, 26 January 2006, Vol 11, Issue 1. Available on line at: http://www.eurosurveillance.org/ew/2006/060126.asp

5. ProMED-mail, Chikungunya - Mauritius and Reunion island (08): Reunion, 5 February 2006; 20060205.0378. Available on line at:

http://www.promedmail.org/pls/promed/f?p=2400:10

01:71123875547331111::NO::F2400_P1001_BACK_P

AGE,F2400_P1001_PUB_MAIL_ID:1000,31895

6. ProMED-mail, Chikungunya - Mauritius and Reunion island (07): Reunion, 4 February 2006; 20060204.0358. Available on line at:

http://www.promedmail.org/pls/promed/f?p=2400:10

01:7914237415148705279::NO::F2400_P1001_BACK

_PAGE,F2400_P1001_PUB_MAIL_ID:1010,31875

7. ProMED-mail, Chikungunya - Seychelles, 3 February 2006. Available on line at:

http://www.promedmail.org/pls/promed/f?p=2400:12

02:4895229872098395377::NO::F2400_P1202_CHEC

K_DISPLAY,F2400_P1202_PUB_MAIL_ID:X,31868

8. Tsai T. Chikungunya Fever. In: Strickland GT, ed. Hunter’s Tropical Medicine and Emerging Infectious Diseases. 8th Ed. WB Saunders Co., Philadelphia. 2000: 246-248.

9. Weaver SC, Tesh RB, Shope RE. Alphavirus infections. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical Infectious Disease. Principles, Pathogens, & Practice. 2nd ed. Churchill Livingston, Philadelphia. 2006:831-838.