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Original ArticleOpen Access
Dengue Classification: Current WHO vs. the Newly Suggested Classification for Better Clinical Application?
Kalayanarooj S 
Introduction: There has been confusion regarding the clinical classification of dengue. The current WHO classification used
since the 70s classifies dengue into dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS). In
2009, a new classification of dengue proposed by WHO Tropical Disease Research (TDR) was published in the WHO TDR
2009 dengue guidelines. This new classification classifies dengue into dengue (D), dengue with warning signs (DW) and
severe dengue (SD).
Objective: To compare the effectiveness in clinical management between the current WHO classification and the newly
suggested classification (TDR) and to assess the 4 criteria of the DHF case definition of the current WHO classification for
possible modification.
Material and Method: A prospective study of suspected dengue patients admitted to the Dengue Unit, Queen Sirikit National
Institute of Child Health between June-August 2009 was done. All cases were managed according to the Thai National Dengue
Guidelines 2008. The final diagnoses were based on the current WHO Classification together with dengue laboratory
confirmation. TDR classification was applied later by the author, using the data from the present study case report forms of
each patient. Statistical analysis comparing clinical and laboratory data between each group of patients was done by using
SPSS version 14.
Results: Total 274 confirmed dengue patients and 24 non-dengue febrile illnesses (ND) were used for analysis. There were
180 DF (65.7%), 53 DHF grade I (19.3%), 19 DHF grade II (6.9%), 19 DHF grade III (6.9%) and 3 DHF grade IV (1.1%)
as classified by the current WHO classification while the suggested TDR classified 85(31%), 160(58.4%) and 29(1.1%) as
D, DW and SD respectively. At least one of the warning signs were found in 50, 53.3, 83, 88.2, 100 and 100% of ND, DF, DHF
grade I, DHF grade II, DHF grade III and DHF grade IV patients. Vomiting and abdominal pain were the 2 most common
warning signs found in both ND and dengue patients. Intensive monitoring and careful medical and IV fluid management
were needed for 94 DHF patients compared to 189 DW and SD patients by the new TDR classification. There were 8 DSS
patients who had AST > 1,000U and one patient presented with encephalopathy. These 8 patients cannot be classified properly
in the current WHO classification. One non-dengue patient who presented with gastrointestinal bleeding was classified as
SD. Bleeding and/or positive tourniquet test was found in and 69.7% of DHF patients. Plasma leakage detected using
hemoconcentration, chest x-ray (CXR) and ultrasonography. Hemoconcentration could detect plasma leakage in 44.7% and
CXR added up evidence of plasma leakage to 86.3%. Ultrasonography was the most sensitive technique to add evidence of
plasma leakage up to 100%. Platelet < 100,000 cells/mm3 was found in 93.5% of DHF patients.
Conclusion: Current WHO classification is recommended for continuing use because the newly suggested TDR classification
creates about 2 times the workload to health care personnel. In addition, the TDR classification needs dengue confirmatory
tests. More than 90% of DHF defined by WHO case definition are dengue confirmed. However, current WHO classification
needs to be modified for more simple and friendly use. The suggested modification is to address plasma leakage as the major
criteria. Tourniquet test positive or bleeding symptoms can be considered as minor criteria. Unusual dengue is proposed to
be added to the current WHO classification to cover those patients who do not fit with the current WHO classification
Keywords: Dengue WHO classification, Dengue fever, DF, Dengue hemorrhagic fever, DHF, Dengue shock syndrome, DSS,
Warning signs
since the 70s classifies dengue into dengue fever (DF), dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS). In
2009, a new classification of dengue proposed by WHO Tropical Disease Research (TDR) was published in the WHO TDR
2009 dengue guidelines. This new classification classifies dengue into dengue (D), dengue with warning signs (DW) and
severe dengue (SD).
Objective: To compare the effectiveness in clinical management between the current WHO classification and the newly
suggested classification (TDR) and to assess the 4 criteria of the DHF case definition of the current WHO classification for
possible modification.
Material and Method: A prospective study of suspected dengue patients admitted to the Dengue Unit, Queen Sirikit National
Institute of Child Health between June-August 2009 was done. All cases were managed according to the Thai National Dengue
Guidelines 2008. The final diagnoses were based on the current WHO Classification together with dengue laboratory
confirmation. TDR classification was applied later by the author, using the data from the present study case report forms of
each patient. Statistical analysis comparing clinical and laboratory data between each group of patients was done by using
SPSS version 14.
Results: Total 274 confirmed dengue patients and 24 non-dengue febrile illnesses (ND) were used for analysis. There were
180 DF (65.7%), 53 DHF grade I (19.3%), 19 DHF grade II (6.9%), 19 DHF grade III (6.9%) and 3 DHF grade IV (1.1%)
as classified by the current WHO classification while the suggested TDR classified 85(31%), 160(58.4%) and 29(1.1%) as
D, DW and SD respectively. At least one of the warning signs were found in 50, 53.3, 83, 88.2, 100 and 100% of ND, DF, DHF
grade I, DHF grade II, DHF grade III and DHF grade IV patients. Vomiting and abdominal pain were the 2 most common
warning signs found in both ND and dengue patients. Intensive monitoring and careful medical and IV fluid management
were needed for 94 DHF patients compared to 189 DW and SD patients by the new TDR classification. There were 8 DSS
patients who had AST > 1,000U and one patient presented with encephalopathy. These 8 patients cannot be classified properly
in the current WHO classification. One non-dengue patient who presented with gastrointestinal bleeding was classified as
SD. Bleeding and/or positive tourniquet test was found in and 69.7% of DHF patients. Plasma leakage detected using
hemoconcentration, chest x-ray (CXR) and ultrasonography. Hemoconcentration could detect plasma leakage in 44.7% and
CXR added up evidence of plasma leakage to 86.3%. Ultrasonography was the most sensitive technique to add evidence of
plasma leakage up to 100%. Platelet < 100,000 cells/mm3 was found in 93.5% of DHF patients.
Conclusion: Current WHO classification is recommended for continuing use because the newly suggested TDR classification
creates about 2 times the workload to health care personnel. In addition, the TDR classification needs dengue confirmatory
tests. More than 90% of DHF defined by WHO case definition are dengue confirmed. However, current WHO classification
needs to be modified for more simple and friendly use. The suggested modification is to address plasma leakage as the major
criteria. Tourniquet test positive or bleeding symptoms can be considered as minor criteria. Unusual dengue is proposed to
be added to the current WHO classification to cover those patients who do not fit with the current WHO classification
Keywords: Dengue WHO classification, Dengue fever, DF, Dengue hemorrhagic fever, DHF, Dengue shock syndrome, DSS,
Warning signs
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