RATIONALE FOR SURVEILLANCE:
Visceral leishmaniasis is endemic in over 60 countries. The incidence is estimated at 500 000 cases each year. It is the most severe form of leishmaniasis and it can be fatal in the absence of treatment. Deadly epidemics frequently occur in the anthroponotic foci of Bangladesh, India, Nepal and Sudan, where humans are believed to be the sole reservoir. Surveillance is essential in establishing disease impact and monitoring efforts towards disease control and detecting epidemics.
RECOMMENDED CASE DEFINITION
An illness with prolonged irregular fever, splenomegaly and weight loss as its main symptoms.
Laboratory criteria for diagnosis
• positive parasitology (stained smears from bone marrow, spleen, liver, lymph node, blood or culture of the organism from a biopsy or aspirated material)
• positive serology (IFA, ELISA)
WHO operational definition:
A case of visceral leishmaniasis is a person showing clinical signs (mainly prolonged irregular fever, splenomegaly and weight loss) with serological (at geographical area level) and/or parasitological confirmation (when feasible at central level) of the diagnosis. In endemic malarious areas, visceral leishmaniasis should be suspected when fever lasts for more than two weeks and no response has been achieved with anti-malaria drugs (assuming drugresistant malaria has also been considered).
RECOMMENDED TYPES OF SURVEILLANCE
Routine monthly reporting of aggregated data from periphery to intermediate and central level.
Active case finding through surveys of selected groups or mass surveys (standardized and periodical) is an alternative to estimate the prevalence of visceral leishmaniasis.
International: Annual reporting from central level to WHO (limited number of countries).
RECOMMENDED MINIMUM DATA ELEMENTS
Individual patient records at peripheral level
Identification data: Unique identifier, age, sex, geographical information, travel history, duration of stay at current residence.
Leishmaniasis data: Clinical features, date of diagnosis, serological/parasitological diagnosis, Leishmania species, treatment outcome.
Aggregated data for reporting
Number of cases by age, sex, type of diagnosis.
RECOMMENDED DATA ANALYSIS, PRESENTATION, REPORTS
Tables: Incidence by geographical area, age, sex, type of diagnosis, risk group, by clinical features, by month/year. Point prevalence (if active case detection).
PRINCIPAL USES OF DATA FOR DECISION-MAKING
• Evaluate the real extent of the problem and the main populations at risk
• Improve and focus the control activities
• Identify technical and operational difficulties
• Evaluate impact of control interventions
• Anticipate epidemics
Visceral leishmaniasis tends to be largely underreported because most of the official data are obtained through passive case detection only. The number of people exposed to infection or infected without any symptoms is much more important than the number of detected cases.
See Regional Communicable Disease contacts on section "Communicable disease contacts in Regional Offices".
Headquarters: 20 Avenue Appia, CH-1211 Geneva 27, Switzerland
Department of Communicable Disease Surveillance and Response (CSR)
E-mail: firstname.lastname@example.org / Surveillancekit@who.ch
Tel: (41 22) 791 38 70
Fax: (41 22) 791 4898 attn CSR