RATIONALE FOR SURVEILLANCE
Dengue fever, including DHF and DSS, is the most significant arthropodborne viral disease worldwide. It occurs in over 100 countries and territories and threatens the health of over 2 500 million people in tropical and subtropical regions. Dengue fever is a severe disease with high epidemic potential. An estimated 500 000 patients, 90% of them below the age of 15, are hospitalized with DHF/DSS every year. WHO aims to accelerate the final development of an attenuated dengue vaccine.
RECOMMENDED CASE DEFINITION
An acute febrile illness of 2-7 days duration with 2 or more of the following: headache, retro-orbital pain, myalgia, arthralgia, rash, haemorrhagic manifestations, leucopenia.
Laboratory criteria for diagnosis
One or more of the following:
• Isolation of the dengue virus from serum, plasma, leukocytes, or autopsy samples
• Demonstration of a fourfold or greater change in reciprocal IgG or IgM antibody titres to one or more dengue virus antigens in paired serum samples
• Demonstration of dengue virus antigen in autopsy tissue by immunohistochemistry or immunofluorescence or in serum samples by EIA
• Detection of viral genomic sequences in autopsy tissue, serum or CSF samples by polymerase chain reaction (PCR)
Suspected: A case compatible with the clinical description.
Probable: A case compatible with the clinical description with one or more of the following:
• supportive serology (reciprocal haemagglutination-inhibition antibody titre ≥1280, comparable IgG EIA titre or positive IgM antibody test in late acute or convalescent-phase serum specimen).
• occurrence at same location and time as other confirmed cases of dengue fever.
Confirmed: A case compatible with the clinical description, laboratory-confirmed.
DENGUE HAEMORRHAGIC FEVER
A probable or confirmed case of dengue and
Haemorragic tendencies evidenced by one or more of the following:
• Positive tourniquet test
• Petechiae, ecchymoses or purpura
• Bleeding: mucosa, gastrointestinal tract, injection sites or other
• Haematemesis or melaena
And thrombocytopenia (100 000 cells or less per mm3)
And evidence of plasma leakage due to increased vascular permeability, manifested by one or more of the following:
• ≥20% rise in average haematocrit for age and sex
• ≥20% drop in haematocrit following volume replacement treatment compared to baseline
• signs of plasma leakage (pleural effusion, ascites, hypoproteinaemia)
DENGUE SHOCK SYNDROME
All the above criteria, plus evidence of circulatory failure manifested by rapid and weak pulse, and narrow pulse pressure (≤20 mm Hg) or hypotension for age, cold, clammy skin and altered mental status.
RECOMMENDED TYPES OF SURVEILLANCE
Areas where no dengue transmission has been detected but where
Aedes aegypti occurs
Surveillance of suspected cases with investigation of clusters of suspected cases for dengue.
Countries where disease is endemic with seasonal variations in transmission, and areas where epidemic dengue occurs
Routine weekly/monthly reporting of aggregated data of suspected, probable and confirmed cases from peripheral to intermediate and central levels.
RECOMMENDED MINIMUM DATA ELEMENTS
Case-based data at the peripheral level
• Case classification (suspected/probable/confirmed), serotype, DHF/DSS present (Y/N)
• Unique identifier, name of patient, age, sex, geographical information
• Date of onset
• Hospitalized (Y/N)
• Travel history during past 2 weeks
Aggregated data for reporting
• Number of cases by age group
• Number of confirmed (and serotype)
• Number of DHF/DSS cases by age group
• Number of hospitalizations and deaths
RECOMMENDED DATA ANALYSES, PRESENTATION, REPORTS
Percentage of DHF/DSS cases and of hospitalizations.
PRINCIPAL USES OF DATA FOR DECISION-MAKING
• Target high risk areas for intervention
• Monitor changes in serotype and rate of DHF/DSS
• Monitor trends in endemic disease or re-emergence of disease
Parallel to disease surveillance, vector surveillance of both larval and adult populations of Ae. aegypti and Ae. albopictus.
See Regional Communicable Disease contacts on section "Communicable disease contacts in Regional Offices".
Headquarters: 20 Avenue Appia, CH-1211 Geneva 27, Switzerland
Communicable Diseases Surveillance and Response (CSR)
E-mail: firstname.lastname@example.org / email@example.com
Tel: (41 22) 791 2658/26367 2111
Fax: (41 22) 791 48 78