When Dengue Causes Death: What to watch for

If you haven't seen a patient with Dengue in your Canadian clinic or emergency department yet, chances are that you will. And they may even show up on your exam - there's a CFPC Priority Topic (also known as The 105 topics) on Travel Medicine. Dengue virus, a mosquito-borne arbovirus transmitted primarily by Aedes mosquitoes, infects an estimated 390 million people a year, many of whom travel back to Canada after becoming ill. Here’s how to stay ahead of it, from diagnosis to prevention.

The spread of dengue has increased due to factors such as climate change, rapid urbanization, and population growth. Although most infections are mild or asymptomatic, the global burden remains high, with over 10,000 dengue-related deaths reported in 2024—a number likely underestimated.

While 60-75% of dengue cases are asymptomatic, symptomatic infections typically present with fever, headache (often described as around or behind the eyes), muscle and joint pain, nausea, and a macular rash.

In about 5% of symptomatic cases, severe dengue can develop, leading to complications including pulmonary edema or ascites, mucosal bleeding, and organ damage such as hepatitis or myocarditis.

When to be worried

Warning signs of severe disease include persistent abdominal pain, vomiting, bleeding, hepatomegaly, and rising hematocrit levels with falling platelet counts, all of which warrant hospital admission and close monitoring. (Of note, white blood cell count is often low in dengue fever, and can be an early clue as this lab result typically lands in your inbox before the dengue serology).

Diagnosing Dengue

Diagnosis of dengue relies on the timing of symptom onset. Within the first week, testing may include PCR, antigen ELISA, and IgM antibody detection. After 7 days, IgM and IgG ELISA are recommended. 

How to Treat

Supportive care remains the mainstay of treatment, with acetaminophen preferred over NSAIDs due to bleeding risks. Patients should also be evaluated for other similar infections like malaria, chikungunya, and Zika.

Know Prevention Counselling The CFPC Priority Topic on Travel Medicine includes "Provide prevention and treatment advice." Since no dengue vaccine is currently approved in Canada, prevention relies heavily on avoiding mosquito bites using repellents, protective clothing, and environmental precautions.

Source: CMAJ