Classifying dengue: a review of the difficulties in using the WHO case classification for dengue haemorrhagic fever

Abstract

Summarybackground The current World Health Organisation (WHO) classification of dengue includes two distinct entities: dengue fever (DF) and dengue haemorrhagic fever (DHF)/dengue shock syndrome; it is largely based on pediatric cases in Southeast Asia. Dengue has extended to different tropical areas and older age groups. Variations from the original description of dengue manifestations are being reported.objectives To analyse the experience of clinicians in using the dengue case classification and identify challenges in applying the criteria in routine clinical practice.method Systematic literature review of post-1975 English-language publications on dengue classification.results Thirty-seven papers were reviewed. Several studies had strictly applied all four WHO criteria in DHF cases; however, most clinicians reported difficulties in meeting all four criteria and used a modified classification. The positive tourniquet test representing the minimum requirement of a haemorrhagic manifestation did not distinguish between DHF and DF. In cases of DHF thrombocytopenia was observed in 8.6-96%, plasma leakage in 6-95% and haemorrhagic manifestations in 22-93%. The low sensitivity of classifying DHF could be due to failure to repeat the tests or physical examinations at the appropriate time, early intravenous fluid therapy, and lack of adequate resources in an epidemic situation and perhaps a considerable overlap of clinical manifestations in the different dengue entities.conclusion A prospective multi-centre study across dengue endemic regions, age groups and the health care system is required which describes the clinical presentation of dengue including simple laboratory parameters in order to review and if necessary modify the current dengue classification.keywords dengue case classification, dengue haemorrhagic fever, plasma leakage, tourniquet test

Dengue: a continuing global threat

“…Recent publications have suggested that the WHO syndromic case definition of DHF/DSS should be evaluated for clinical utility [58][59][60][61][62] . A prospective multi-centre study in several Latin-American and Southeast asian countries is planned that will provide standardized descriptions of dengue clinical presentations in the context of the current WHO case definitions.…”

Dengue myocarditis in Singapore: two case reports

“…He was sent home on antipyretics. Two days later, his full blood count, ordered by a private primary care physician, showed leukopaenia (1.3 9 10 9 /L; normal range 4.0-11.0 9 10 9 /L), thrombocytopaenia (75 9 10 9 /L; normal range 150-400 9 10 9 /L) and normal [7]. This has been addressed in the WHO 2009 guidelines with specific inclusion of severe bleeding and severe organ involvement as separate categories of severe dengue disease, as well as in a regional update to the 1997 guidelines, which covers unusual or atypical manifestations under the category of Expanded Dengue Syndrome independent of DHF status [8].…”

What does dengue disease surveillance contribute to predicting and detecting outbreaks and describing trends?

“…A well organized routine reporting system with laboratory support in Puerto Rico was shown to reflect the disease trend accurately and provide data for an alert system. Sensitivity can be increased by combining different approaches and by using an appropriate case classification which is less complex and rigid than the actual one and reflects the different levels of disease severity (Bandyopadhyay et al 2006); some countries report all the clinical manifestations of dengue and others only DHF, which makes international comparisons difficult.…”

“…Thus it is crucial to distinguish between seasonal variation and outbreaks by using a surveillance system that is adequate for alerting the response system at an early stage. A complicating factor of dengue disease surveillance is the variation seen in the clinical picture, which includes a large number of asymptomatic and mild cases (Bandyopadhyay et al 2006) and misdiagnosis through confounding dengue with other diseases. The objectives of a public health surveillance system are (CDC 2001):…”