A guide for health professionals working with
immigrant and refugee children and youth

Dengue

Key points

  • The number of cases of dengue is increasing worldwide, as are the number of countries with endemic infection.
  • Dengue should be suspected in patients with a history of arrival within 2 weeks from an endemic country, who have: sudden onset of high fever and signs or symptoms of a rash, nausea or vomiting, incapacitating myalgia or arthralgia, headache and leukopenia.
  • There is no specific treatment for dengue. Aggressive supportive care is required.
  • There is no vaccine. Prevention requires vector control and personal protection to decrease mosquito bites.

Epidemiology

Dengue is the most common viral disease transmitted by mosquitoes worldwide.1 It is caused by one of four Flavivirus serotypes (DEN-1, 2, 3 and 4), which are transmitted by Aedes mosquitoes, a daytime biting mosquito present more often in urban than in rural areas (Figure 1).1 These mosquitos bite especially in the early morning and in the evening before dusk (the opposite of the Anopheles mosquito that transmits malaria). About 40% of the global population live in areas where dengue is endemic.2

Figure 1. Female Aedes aegypti mosquito

Figure 1. Female Aedes aegypti mosquito

Source: Centers for Disease Control and Prevention/Prof. Frank Hadley Collins, Dir., Cntr. for Global Health and Infectious Diseases, University of Notre Dame. Photo credit James Gathany.

Each year, an estimated 50 to 100 million dengue infections and 24,000 deaths due to dengue occur worldwide.1 The mortality rate for severe infection can be up to 15%, but is less than 1% with appropriate medical intervention.1 The rate of infection in young visitors or immigrants to Canada and in those returning from travel is not known, but anecdotal reports suggest that it is increasing as the range of countries where dengue expands. Dengue is now the second-most common diagnosis in the returning traveller, after malaria.3

Risk factors

Recent newcomers to Canada from a high-risk area may be at risk of infection, as are recent travellers to a high-risk area. Dengue develops within 2 weeks of exposure. Thus, if the onset of illness occurs <2 weeks after possible exposure, dengue must be considered. If onset takes longer than 2 weeks, dengue infection is improbable.

High-risk regions generally include tropical and subtropical regions, as shown in Figure 2.4 However, there have also been recent reports of endemic cases in the US and Europe.6 An interactive map that shows global epidemiological data on dengue is available from the Centers for Disease Control and Prevention (CDC).

Figure 2: Distribution of global dengue risk, WHO 20124

Figure 2: Distribution of global dengue risk, WHO 2012

Source:  Reproduced, with the permission of the publisher, from Global Strategy for Dengue Prevention and Control, 2012-2020 (Fig. 2, Page 2 http://apps.who.int/iris/bitstream/10665/75303/1/9789241504034_eng.pdf, accessed 07 November 2013).

Clinical clues

Coming from or history of travel to an endemic country is key.

Signs of dengue fever generally develop 4 to 7 days post-infection but can occur as late as 14 days after the mosquito bite and may include:1

  • High fever with sudden onset- sometimes bi-phasic
  • Severe headache
  • Opthalmoplegia- retro-orbital pain
  • Incapacitating myalgias and arthralgias (“Break bone” fever)
  • Nausea
  • Vomiting
  • Rash appearing between fever spikes
  • Occasional bleeding manifestations
  • Leukopenia

Severity of infection

Illness can range from non-apparent infection to classic dengue fever, severe dengue (previously known as dengue haemorrhagic fever), and dengue shock syndrome.1 Severe dengue causes more serious illness and deaths in children than malaria in some Asian and Latin American countries. The WHO has developed case definitions for dengue5, but the differences among these definitions are often blurred.

Figure 3. Suggested dengue case classification and levels of severity

Source: Reproduced, with the permission of the publisher, from Dengue guidelines for diagnosis, treatment, prevention and control (Fig. 1.4, Page 11 http://www.who.int/csr/resources/publications/dengue_9789241547871/en/, accessed 07 November 2013).

Tourniquet test: A test of capillary fragility, caused by an abnormality in the capillary wall or thrombocytopenia, in which a blood pressure cuff is applied for 5 minutes to a person’s arm and inflated to a pressure halfway between the diastolic and systolic blood pressure. The number of petechiae within a circumscribed area of the skin may be counted, or the results may be reported in a range from negative (no petechiae) to +4 positive (confluent petechiae). Source: Mosby’s Medical Dictionary, 8th edition. © 2009, Elsevier: http://medical-dictionary.thefreedictionary.com/tourniquet+test (Accessed November 7, 2013).

HCT: Hematocrit DSS: Dengue shock syndrome

Risk factors for severity

Risk factors for severity of disease include:5

  • Second infection: Recovery from infection by one serotype followed by subsequent infection with another serotype
  • Age: Young children are at greater risk of dengue shock than adults because they are less able to compensate for capillary leakage
  • Ethnicity: Rates of severe dengue appear to be higher in persons of non-African ancestry
  • Chronic diseases (e.g., asthma, sickle cell anaemia, diabetes)

Diagnosis

Consider dengue in the differential diagnosis in patients with:1

  • Fever, AND
  • If coming from or history of travel to a risk area within 2 weeks of onset of symptoms

In patients who present with fever and have travelled to or from a dengue-enemic region, it is also important to consider malaria, typhoid fever, leptospirosis and influenza in the differential diagnosis.6

Criteria for diagnosis of dengue are noted in Figure 3.

Consider serological, molecular or other tests (e.g., antigen detection) to confirm diagnosis after talking to your laboratory, but recognize that there may be a delay in confirmation. Clinical decisions must be based on patient history and findings, with lab confirmation coming later.

During the febrile period (especially in early stages), antibodies may not be present. During abatement of the fever, RNA, virion or dengue protein may be difficult to detect. The Committee to Advise on Tropical Medicine and Travel (CATMAT) recommends serological testing of acute-phase (collected 0 to 5 days from fever onset) and convalescent-phase (collected 6 to 30 days from fever onset) serum samples.1 The National Microbiology Laboratory in Winnipeg provides the diagnostic services for dengue in Canada. Some specialty laboratories also offer this service; check with your local  laboratory.

Management

There is no specific antiviral therapy currently available for dengue.1 Management guidelines have been published by the WHO.5,7

Aggressive supportive care is required for serious disease.

  • Due to capillary leakage, fluid management must be proactive and signs of shock recognized quickly.
  • Bleeding must also be managed proactively and salicylates avoided, as they may exacerbate bleeding.
  • Anticonvulsants may be required if seizures occur.
  • Multi-organ failure may occur with liver, renal and cardiac involvement. Recovery can be slow and complicated.
  • Long-term sequelae, such as cardiomyopathy and persistent fatigue, may occur.

Prevention

There is no vaccine against dengue at present, although efforts are underway to develop one. Personal protective measures include using insect repellent, bednets when sleeping  and clothing all reduce the risk of mosquito bites. Further information on preventing insect bites can be found in the Travel-Related Illness section.

Selected resources

References

  1. Committee to Advise on Tropical Medicine and Travel (CATMAT). Statement on dengue. Can Commun Dis Rep 2009;35(April 2009):1-11.
  2. American Academy of Pediatrics. Dengue. In: Pickering Lk, Baker CJ, Kimberlin DW, et al, eds. Red Book: 2012 Report of the Committee on Infectious Disease. Elk Grove Village, IL: AAP, 2012:305-7.
  3. Chen LH, Wilson ME . Dengue and chikungunya infections in travelers. Curr Opin Infect Dis 2010;23(5):438-44.
  4. WHO. Global strategy for dengue prevention and control 2012-2020. Geneva, Switzerland: WHO, 2012: http://apps.who.int/iris/bitstream/10665/75303/1/9789241504034_eng.pdf
  5. WHO. Dengue guidelines for diagnosis, treatment, prevention and control. Geneva, Switzerland: WHO, 2009: www.who.int/rpc/guidelines/9789241547871/en/
  6. Duber HC, Kelly SM. Febrile illness in a young traveler: Dengue fever and its complications. J Emerg Med 2013;45(4):526-9.
  7. WHO. Dengue and severe dengue. Fact sheet N°117. September 2013: www.who.int/mediacentre/factsheets/fs117/en/

Editor(s)

  • Noni MacDonald, MD

Last updated: July, 2014

Also available at: http://www.kidsnewtocanada.ca/conditions/dengue
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Caring for Kids New to Canada is a resource for health professionals. The information here is not a substitute for medical advice, nor does it indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate.

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