Dengue: Not Every Tropical Fever Is Malaria

Tyler M. Sharp, PhD


April 28, 2014

Editorial Collaboration

Medscape &

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Hi. I am Dr. Tyler Sharp from the Centers for Disease Control and Prevention (CDC). I am pleased to speak with you as part of the CDC Expert Commentary series on Medscape. Today I will be sharing recent findings about dengue in Africa and the implications for travelers' health. 

Dengue is an infectious disease caused by any of 4 mosquito-transmitted viruses, called dengue virus types 1, 2, 3, and 4. Most individuals with dengue have an acute febrile illness lasting about 1 week, with body, muscle, and joint pain; headache and eye pain; rash; and in some cases, minor bleeding such as gum or nose bleeds. However, a small proportion of dengue cases will progress to severe dengue, previously referred to as dengue hemorrhagic fever and dengue shock syndrome. Patients with severe dengue may experience clinically significant hemorrhage and develop pleural effusions, ascites, and signs of shock caused by plasma leakage. The case fatality rate for severe dengue can be under 1% with early recognition of severe disease and initiation of supportive care.[1]

Distribution. Dengue is endemic throughout the tropics and subtropics, and residents of and travelers to these areas are at risk for infection. Recent studies estimate that, worldwide, roughly 400 million dengue virus infections occur each year.[2] About one fourth (100 million) of these infected individuals will have dengue or severe dengue, and the remaining infections will be asymptomatic or subclinical. Although the burden of dengue is greatest in South-Central and Southeast Asia, it is now believed that the burden of dengue in Africa is equivalent to that of the Americas, where roughly 65 million dengue virus infections occur annually. (See Dengue Map)

CDC has recently been involved in 4 dengue outbreak investigations on the African continent, in Somalia, Kenya, Angola,[3] and Tanzania. Partly the result of the recent availability of dengue rapid diagnostic tests, clinical awareness of dengue is improving in these resource-limited areas. Diagnostic testing has revealed that not all acute febrile illnesses in Africa are malaria. In fact, a recent study from northern Tanzania demonstrated that among febrile patients clinically diagnosed with malaria, only 1% had laboratory evidence of malaria.[4]

Diagnosis. Dengue is frequently misdiagnosed as malaria.[5] For this reason, clinicians in Africa, as well as those seeing patients recently returned from Africa, should include dengue in their differential diagnosis of patients with acute febrile illness.

In the United States, dengue diagnostic testing is available from both private and some local public health laboratories. Testing should include both polymerase chain reaction (PCR) and IgM enzyme-linked immunosorbent assay (ELISA) to detect the virus itself and the immune response to it, respectively. In 2010, dengue was made nationally reportable in the United States, and therefore all suspected dengue cases should be reported to your local health department.

Treatment. One of the main determinants of patient outcome is the timing and quality of clinical care that dengue patients receive.[1] Initiating prompt, supportive care and providing close clinical monitoring can reduce the case fatality rate of patients with severe dengue from approximately10% to less than 1%. Therefore, it is very important for clinicians to identify dengue when infected patients first seek care, offer them anticipatory guidance, and know how to manage severe dengue, particularly through close monitoring and maintenance of hemodynamic status.

CDC is pleased to announce a recently developed course for healthcare providers on the clinical management of dengue patients, called "Dengue Clinical Case Management." This course is currently available online, and clinicians who complete it will receive continuing medical education credits. We recommend that this course be completed by clinicians in the United States who might see patients returning from the tropics, as well as clinicians who practice in the tropics or subtropics. Thank you for your attention.

Web Resources

CDC: Dengue Training Opportunities (with CME courses)

CDC: Dengue

CDC/Google: Dengue Map

Lieutenant Commander Tyler M. Sharp, PhD, is an epidemiologist at the Centers for Disease Control and Prevention (CDC) Dengue Branch in San Juan, Puerto Rico. A native of Bowling Green, Ohio, he attended secondary school in the Chicago area and received his bachelor of science degree in molecular biology and genetics from the University of Guelph in Ontario, Canada. He received additional training at Montana State University - Bozeman and the Medical Research Council Division of Virology in Glasgow, Scotland. He completed his doctorate in molecular virology and microbiology at Baylor College of Medicine in Houston, Texas, in the laboratory of Dr. Mary K. Estes, where he studied the molecular mechanisms of norovirus pathogenesis. During his graduate study, he received additional training at the National Institute for Infectious Diseases in Tokyo, Japan. He joined CDC in 2010 as an Epidemic Intelligence Service officer stationed at CDC Dengue Branch. His current public health and research interests are the epidemiology and pathophysiology of emerging infectious diseases, including dengue, leptospirosis, and melioidosis. He enjoys international travel, hiking and camping, scuba diving, and avoiding infection with the pathogens he studies (thus far with limited success).