Clinical Updates
8 August 2006
Dengue update
Dengue is an arthropod-borne virus of the Flaviviridae family. There are four serotypes of dengue virus classified as dengue 1 to 4. The virus is transmitted to man by the bite of an infected Aedes mosquito; A. aegypti is the principle vector, but A. albopictus is also of importance.
Dengue is recognised in over 100 countries and between 250,000 to 500,000 cases are reported to the World Health Organization annually. The current outbreaks of disease reflect where the major disease burden of dengue occurs: south-east Asia, Central and South America and the Carribean, and the western Pacific.
The majority of cases of dengue are sub-clinical or mild. Following an incubation period of five to eight days, a fever develops which lasts from one to five days. Other symptoms include headache, myalgia, and cough. A maculopapular rash typically spreading from the trunk to the limbs and face develops between three and five days after onset of the illness. Most patients will make a rapid recovery three to four days after onset of the rash.
Dengue can progress to the more serious dengue haemorrhagic fever (DHF). This is more common in children and rarely seen in travellers. It is not certain what precipitates such progression, although previous infection with a different serotype of dengue may predispose to DHF on re-infection. During DHF there is a sudden deterioration with diffuse bleeding and shock, leading to organ failure.
There is no specific treatment for dengue or DHF. Supportive care and management of symptoms are the standard.
This update reports on some of the current outbreaks of dengue, and is not a comprehensive listing of all dengue outbreaks.
Asia
Outbreaks of dengue have been reported across the region during 2006. In Thailand, 1,187 cases of dengue fever have been reported from the provinces of Kamphaeng Phet, Nakhon Sawan, Phichit and Uthai Thani, and the Ministry of Public Health has now declared these areas “alert zones” for dengue fever [1].
As of 25 July 2006, 554 cases of dengue fever have been reported in the Bangladeshi capital of Dhaka. Insecticide spraying is now being carried out in the city [2].
In the southern provinces of Viet Nam, 20,980 cases of dengue fever have been reported during 2006, 62% more than in the same period in 2005 [3]. In the capital, Ho Chi Minh City, around 3,500 cases have been reported with 200 cases per week being hospitalised during July 2006. The Vietnamese Ministry of Health has instructed local government in affected areas to start an anti-mosquito campaign, train health workers, and inform the public on insect avoidance measures [4].
Central and South America
Dengue fever is endemic across South America and during 2006, cases have been reported from the majority of countries [5]. In Venezuela, 23,733 dengue cases were recorded between 1 January and 15 July 2006; 1,296 of which were classified as dengue haemorrhagic fever. During the week of 9 to 15 July 2006, 920 dengue cases were diagnosed [6].
As of 15 June 2006, 1,301 cases of dengue have been reported in El Salvador. The president of El Salvador has declared a state of emergency in the departments of San Salvador, Libertad, Santa Ana, and Cabañas; a control programme involving insecticide spraying and destruction of mosquito larval breeding sites is underway [7].
Advice for travellers
There is no vaccine available to protect against dengue.
Travellers to endemic areas can reduce their risk of dengue by practising mosquito bite avoidance measures. Aedes mosquitoes responsible for transmitting dengue are active during daylight hours. Particular vigilance with bite avoidance should be taken around dawn and dusk.
References
1. Thailand Ministry of Public Health. Dengue alert in 4 Provinces, [Cited 4 August 2006]. Available at: http://eng.moph.go.th/ContentDetails.php?intContentID=13955&
2. Centre of Excellence in Disaster Management and Humanitarian assistance. Asia-Pacific disease outbreak / surveillance report, 28 July 2006. [Cited 4 August 2006]. Available at: http://www.thedailystar.net/2006/07/25/d6072501107.htm
3. Thahn Nien News. Dengue fever plagues Southern Vietnam, 12 July 2006. [Cited 4 August 2006]. Available at: http://www.thanhniennews.com/healthy/?catid=8&newsid=17641
4. Thahn Nien News. Viet Nam metro in the grip of dengue fever, 20 July 2006. [Cited 4 August 2006]. Available at: http://www.thanhniennews.com/healthy/?catid=8&newsid=17935
5. Pan American Health Organization. 2006: Number of reported cases of dengue & dengue hemorrhagic fever (DHF), region of the Americas (by country and subregion, 22 June 2006. [Cited 4 August 2006]. Available at: http://www.paho.org/ENGLISH/AD/DPC/CD/dengue-cases-2006.htm
6. ProMED mail. Dengue / DHF update (28), 30 July 2006, [cited 4 August 2006] Available at: http://www.promedmail.org/pls/promed/f?p=2400:1202:1625236
5295472482033::NO::F2400_P1202_CHECK_DISPLAY,F2400_
7. Pan American Health Organization. Dengue in El Salvador. [Cited 4 August 2006]. Available at: http://www.paho.org/English/DD/PED/dengue_elsalvador.htm
Links and Further reading
NaTHNaC dengue information sheet.
http://www.NaTHNaC.org/pro/factsheets/dengue.htm
Guzmán MG, Kouri G. Dengue: an update. Lancet Inf Dis. 2001; 2: 33-42
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