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Distinguishing dengue from febrile illnesses could save thousands

2011 ASTMH

PHILADELPHIA — With millions of dengue cases occurring annually, new tools are needed to diagnose dengue from other febrile illnesses — which appear similar to dengue, particularly in the early stages of disease — according to a presenter here at the American Society of Tropical Medicine and Hygiene 60th Annual Meeting.

Hope Biswas, PhD, and colleagues examined data from the multiyear, ongoing Pediatric Dengue Cohort Study of 3,800 children aged 2 to 14 years in Managua, Nicaragua. The frequency of clinical signs and symptoms by day of illness was used to generate models for the association of signs and symptoms with testing dengue-positive. Odds ratios and 95% confidence intervals were calculated using generalized estimating equations that account for repeated measures and were compared with standard logistic regression models that do not analyze the data longitudinally. The frequency of meeting WHO case definition for suspected dengue also was examined.

“Distinguishing dengue from other febrile illnesses early in illness is challenging, since symptoms are nonspecific and common to other febrile illnesses, such as malaria, leptospirosis, rickettsiosis and typhoid fever, in dengue-endemic countries,” Biswas said. “In addition, the natural history of pediatric dengue early in illness in a community-based setting has not been well-defined.”

Twenty-five percent of dengue-positive cases did not meet WHO case definition of dengue, whereas the proportion of laboratory-confirmed dengue virus infections that met WHO case definition significantly increased by age. The frequency of signs and symptoms varied by day of illness, dengue status and disease severity. Daily analysis of clinical signs and symptoms beginning early in the course of illness combined with longitudinal statistical analysis demonstrated significant associations with testing dengue-positive and significant differences compared with non-longitudinal methods.

“Few other prospective community-based cohort studies have analyzed early clinical features in pediatric dengue compared to other febrile illnesses, and none that we are aware of have used longitudinal statistical methods that account for correlations between repeated measures on patients,” the researchers said.

In the study, researchers demonstrated how certain signs and symptoms — petechiae, leukopenia and positive tourniquet test — discriminate between dengue cases and patients with other febrile illnesses, whereas other signs and symptoms — abdominal pain beginning on the third day and a platelet count of less than 150,000 cells/mm3 — discriminate severe dengue cases from dengue fever cases.

“These results are important for physicians in dengue-endemic areas because they reflect the relative importance of signs and symptoms early in illness in real time and have implications for diagnosis and treatment,” Biswas said.

Disclosure: Dr. Biswas reports no relevant financial disclosures.

For more information:

• Biswas H. #LB-2120. Early clinical features of dengue virus infection in Nicaraguan children: A longitudinal analysis. Presented at: the American Society of Tropical Medicine and Hygiene 60th Annual Meeting; Dec. 4-8, 2011; Philadelphia.

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