Dengue Fever

Released: February 6, 2008

The Public Health Agency of Canada (PHAC) recommends that travellers use personal protective measures against mosquito bites to prevent getting dengue disease while travelling to countries where dengue disease may occur. There is no vaccine or medication that protects against dengue.

Dengue disease is the most common mosquito-borne viral disease of humans; the burden of dengue disease continues to escalate globally. While people recover from most dengue infections, some can be more severe and potentially deadly.  Travellers need to know if there is a risk of dengue disease occurring in the country where they will be travelling.

What is Dengue Fever and Dengue Haemorrhagic Fever?

The disease can present itself in two forms, although the distinction between the two forms is not always clear:

• Dengue fever (DF) begins with the sudden onset of fever, headache, muscle aches and joint pain, pain behind the eyes and a faint rash. The fever usually lasts from three to five days, and rarely more than seven days.
• Dengue haemorrhagic fever (DHF), a more severe and potentially deadly form of the disease is characterized by loss of appetite, vomiting, intense abdominal pain, shock and bleeding from the nose or under the skin. DHF is more common in people who have been infected by dengue before, have weakened immune systems, or are under the age of 15.

Transmission

Dengue virus is transmitted to humans by infected day-time biting mosquitoes (Aedes aegypti). This mosquito species is most often found in or near human dwellings in urban and surrounding areas. Risk of dengue disease increases when environmental conditions promote increases in the mosquito populations (e.g. during and immediately following rainy seasons, flooding). However outbreaks can occur at any time. 

Geographic Distribution

Dengue disease occurs in tropical and subtropical areas and has been reported in over 100 countries in the Caribbean, South, Central and North America, Africa, the Pacific Islands, Hawaii, Asia and Australia. For a map outlining where there is a risk of dengue transmission due to presence of the mosquito vector, please see Figure 1 :  Dengue Transmission Risk reproduced from the World Health Organization's: International and Travel Health Publication.
For additional information on dengue please see PHAC's Disease Information Backgrounder on Dengue Fever

Figure 1:  Dengue Transmission Risk
Please note that the term “vector” in this map means the type of mosquito that can transmit the dengue virus.

Recommendations

The Public Health Agency of Canada (PHAC) recommends that travellers use personal protective measures to reduce the risk of being bitten by day-time biting mosquitoes when travelling to destinations where dengue disease may occur.

Personal Protective Measures:

• Apply insect repellent to exposed skin. Use DEET-based products only on exposed areas of skin. Remove the repellent with soap and water when it is no longer required.
• Cover up! The less exposed skin you have, the less likely you are to be bitten. Wear light-coloured, long-sleeved shirts and long pants.
• Sleep under a mosquito net when napping during the day. Mosquito nets protect you when you're sleeping. Permethrin-treated nets are much more effective than untreated nets and are safe for children and pregnant women. 
• Consider your accommodations. When possible, remain in well-screened or completely enclosed, air-conditioned areas.

More detailed information on preventing mosquito bites can be found at: http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/05vol31/asc-dcc-4/index.html

Monitor your health

Travellers who, on their return to Canada, develop any fever that is associated with skin rash, bleeding or easy bruising should seek immediate medical attention and inform their physician, without being asked, that they have been travelling or living in an area where dengue disease may occur and what, if any, treatment they have received.

As a reminder…

PHAC strongly recommends that Canadian travellers consult their personal physician or a travel clinic at least six weeks prior to international travel, regardless of destination, for an individual risk assessment to determine their individual health risks and their need for vaccination, preventative medication, and personal protective measures.
PHAC recommends, as well, that travellers who become sick or feel unwell on their return to Canada should seek a medical assessment with their personal physician. Travellers should inform their physician, without being asked, that they have been travelling or living outside of Canada, and where they have been.

Additional information:

• Information on Dengue from the Public Health Agency of Canada
  Disease Information Backgrounder on Dengue Fever
  Committee to Advise on Tropical Medicine and Travel's “Statement on Personal Protective Measures to Prevent Arthropod Bites”

• External Sources of Information
  World Health Organization: Dengue Page
  Centers for Disease Control and Prevention: Dengue Fever Fact Sheet