Volume 22-04
15 February 1996

[Table of Contents]

Committee to Advise on Travel and Tropical Medicine (CATMAT)*

TRAVEL MEDICINE RECOMMENDATION: DENGUE FEVER AND INTERNATIONAL TRAVEL

The incidence of dengue fever, a mosquito-transmitted disease, is rising in areas frequented by Canadian tourists. A marked increase in cases has been observed over the past decade, especially in tropical and subtropical areas of Central and South America. This increased activity has recently been associated with the re-emergence of one type of the virus that has not been observed in Central America for some time (1).

Dengue fever is an acute febrile illness, associated with myalgias, arthralgias, headache, and skin rash. It is caused by one of four serotypes of the dengue virus. The disease is distributed throughout the tropical and subtropical areas of the globe and has been reported in over 100 countries (1) (see Table 1); worldwide, there may be up to 2 billion people at risk (2) . All four of the dengue virus serotypes are circulating in Asia, Africa, and the Americas. The incidence of dengue has increased markedly in Central and South America and areas of the Caribbean since 1980 (2) .

Dengue fever is commonly spread by urban mosquitoes of the Aedes genus, and one of the most common vectors, Aedes aegypti, lives in close proximity to man. Increases in prevalence are believed to be related to increasing urbanization and other social factors that favour increased mosquito reproduction (3) .

While the disease is often mild and self-limiting, it may present in a severe form associated with hemorrhagic complications, shock, and, in some cases, death. This severe form, called dengue hemorrhagic fever (DHF), may be associated with certain strains of the virus or may be related to the age or immune status of the individual infected. DHF is more common in people less than 15 years of age and in people having their second infection (4) .

Although dengue fever has been reported in some international travellers, in general there is a low risk of DHF in tourists returning to the developed world (5,6) .

Prevention is key, because there is no specific therapy for dengue fever. International travellers to areas endemic for dengue fever should use personal measures to avoid the day-biting Aedes mosquitoes. These precautions should be added to their efforts to avoid the night-biting Anopheles mosquito responsible for malaria.

Personal Measures to Avoid Mosquitoes

All travellers to areas endemic for dengue fever are advised to use personal insect protective measures to reduce the risk of day-biting mosquitoes.

Any measure that reduces exposure to the daytime-feeding female Aedes mosquito will also reduce the risk of acquiring dengue fever: remaining in well-screened or completely enclosed air-conditioned areas, and wearing clothing that reduces the amount of exposed skin. In addition, the use of insect repellent on exposed skin is recommended. Insect repellents containing N,N diethyl-methyltoluamide (DEET) are the most effective. The concentration of DEET varies from product to product, and the higher concentrations protect for longer periods of time. In rare instances, application of insect repellents with high concentrations (> 35%) of DEET has been associated with seizures in young children; therefore, DEET should be applied sparingly to exposed surfaces only and washed off after the person comes indoors. Thirty-five per cent DEET protects for 4 to 6 hours, whereas 95% DEET protects for 10 to 12 hours. New formulations of DEET are available containing a lower concentration but protecting for longer periods.

There are currently no vaccines for preventing the acquisition of dengue fever.

Medical Intervention

Fever that develops within 2 weeks of leaving a dengue-endemic area should be reported to a physician and the returned traveller should advise the physician of recent travel to tropical regions.

Any fever that is associated with skin rash, bleeding, easy bruising, or other hemorrhagic phenomena, particularly in children, should be immediately brought to the attention of a physician.

In Canada, laboratory investigation of suspected dengue fever may be undertaken at Zoonotic Diseases, National Laboratory for Special Pathogens, Bureau of Microbiology, LCDC, Tunney's Pasture, Ottawa, Ontario, K1A 0L2 [Tel: 613-954-0757, Fax: 613-954-0207] and the Vector-Borne and Special Pathogens Unit,F-2 Laboratory Services Branch, Ontario Ministry of Health, 81 Resources Road, Etobicoke, Ontario, M9P 3R1 [Tel: 416-235-5766 (5734), Fax: 416-235-5867].

Given current patterns of dengue transmission, there are no indications to suggest that routine travel to areas where dengue is reported should be avoided, providing that travellers adhere to the insect barrier precautions noted above.

More information on specific countries reporting cases of dengue fever can be obtained from the Laboratory Centre for Disease Control's FAXlink service by dialing 613-941-3900 from a fax phone.

Table 1 Global Distribution of Dengue Fever Risk of Epidemic Dengue

AMERICAS

Anguilla, French Guiana, St. Lucia, Antigua & Barbuda, Grenada, St. Martin, Argentina, Guadeloupe, St. Vincent, Aruba, Jamaica*, Suriname, Bahamas, Martinique, Trinidad & Tobago, Barbados, Montserrat, United States, British Virgin Islands, Netherlands Antilles, Virgin Islands, Dominica, St. Kitts & Nevis

AFRICA

Benin, Ghana, Seychelles, Botswana, Guinea, Sierra Leone, Burundi, Guinea-Bissau, Somalia, Cameroon, Kenya, Sudan, Central African Republic, Liberia, Tanzania, Congo, Madagascar, Togo, Ethiopia, Malawi, Uganda, Equatorial Guinea, Mauritius, Zambia, Gabon, Rwanda, Zimbabwe, Gambia, Senegal

ASIA

China*, Papua New Guinea

OCEANIA

Solomon Islands

Recent Dengue Activity

AMERICAS

Belize, Dominican Republic, Nicaragua, Bolivia, Ecuador*, Panama*, Brazil*, Guatemala*, Paraguay, Colombia*, Guyana, Puerto Rico, Costa Rica*, Haiti*, Venezuela*, Cuba*, Mexico*

AFRICA

Angola, Ivory Coast, Nigeria, Burkina, Faso, Mozambique

ASIA

Bangladesh, Laos*, Singapore*, Brunei, Malaysia*, Sri Lanka*, India*, Maldives*, Taiwan, Indonesia*, Myanmar, Thailand*, Kampuchea*, Philippines*, Vietnam*

MIDDLE EAST

Saudi Arabia

OCEANIA

Australia*, New Caledonia, Tahiti, Cook Islands, Palau, Tonga, Fiji, Samoa, Vanuata, Kiribati* * indicates countries that have experienced DHF outbreaks

Sources

1. WHO. Preventing dengue and dengue haemorrhagic fever. WHO: Geneva, 1994.

2. Gubler DJ, Trent DW. Emergence of epidemic dengue/dengue hemorrhagic fever as a public health problem in the Americas. Infect Agents Dis 1994;2:383-93.

3. Wilson ME. A world guide to infections. New York: Oxford University Press, 1991.

4. PAHO. Press releases. 1995.

References

1. PAHO. Early warning against new diseases needed, experts say. June 15, 1995. Washington, DC. Press release.

2. Lam SK. Dengue haemorrhagic fever. Rev Med Microbiol 1995;6:39-48.

3. CDC. Dengue update. Advisory memorandum no. 109, March 10, 1995. Atlanta, GA: CDC.

4. WHO. Dengue and dengue haemorrhagic fever. Wkly Epidemiol Rec 1994;69:237-39.

5. Lange WR, Beall B, Denney SC. Dengue fever: a resurgent risk for the international traveler. Am Fam Physician 1992;45:1161-68.

6. Cunningham R, Milton K. Dengue haemorrhagic fever. Br Med J 1991;302:1083-84.

* Members: Dr. W. Bowie; Dr. L. S. Gagnon; Dr. S. Houston; Dr. K. Kain; Dr. D. MacPherson (Chairman); Dr. V. Marchessault; Dr. H. Onyett; Dr. R. Saginur; Dr. D. Scheifele (NACI): Dr . F. Stratton; Mrs. R. Wilson (CUSO).

Ex-Officio Members: Dr. D. Carpenter (DND); Dr. E. Gadd (HPB); Dr. B. Gushulak (Secretary); Dr. H. Lobel (CDC); Dr. A. McCarthy (LCDC and DND); Dr. S. Mohanna (MSB); Dr. M. Tipple (CDC).

[Previous] [Table of Contents] [Next]