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close this bookWHO Recommended Surveillance Standards (WHO; 1999; 157 pages)
View the documentAcknowledgements
View the documentAcronyms
View the documentIntroduction
View the documentNational Coordination of Communicable Disease Surveillance
View the documentExplanatory notes
View the documentSurveillance activities: criteria and WHO Department
View the documentCommunicable disease contacts in Regional Offices
close this folderDiseases
View the documentB20-B21-B22-B23-B24 AIDS
View the documentA22 Anthrax
View the documentA23 Brucellosis
View the documentA00 Cholera
View the documentA81.0 Creutzfeldt-Jakob disease
View the documentA90, A91 Dengue fever (A90) including Dengue haemorrhagic fever (DHF) & Dengue shock syndrome (DSS, A91)
View the documentA36 Diphtheria
View the documentB72 Dracunculiasis (Guinea worm disease)
View the documentA98.3, A98.4 Ebola-Marburg viral diseases
View the documentA83.0 Japanese encephalitis
View the documentB74 Lymphatic filariasis
View the documentB96.3 Haemophilus influenzae type b
View the documentB15-B17 Acute viral hepatitis
View the documentB20-B24 HIV infection
View the documentJ10, J11 Influenza
View the documentA96.2 Lassa fever
View the documentA48.1 Legionellosis
View the documentB55.1, B55.2 Cutaneous leishmaniasis
View the documentLeishmania / HIV co-infections
View the documentB55.0 Visceral leishmaniasis
View the documentA30 Leprosy
View the documentA27 Leptospirosis
View the documentB50-54 Malaria
View the documentB05 Measles
View the documentA39 Meningococcal disease
View the documentA87 Viral meningitis
View the documentB73 Onchocerciasis
View the documentA37.0 Pertussis
View the documentA20 Plague
View the documentA36 Poliomyelitis
View the documentA82 Rabies
View the documentA02.0 Salmonellosis
View the documentB65 Schistosomiasis
View the documentA50-52 Syphilis
View the documentA33 Tetanus, neonatal
View the documentB56-0, B56-1 African trypanosomiasis
View the documentB57 American trypanosomiasis
View the documentA15-A19 Tuberculosis
View the documentA75.3 Scrub typhus
View the documentA95.9 Yellow fever
open this folder and view contentsSyndromes
View the documentAnnex 1 Software free and in the public domain
View the documentAnnex 2 Proposed surveillance definitions
View the documentAnnex 3 Role and use of Geographic Information Systems (GIS) and mapping for epidemiological surveillance
 

B65 Schistosomiasis

RATIONALE FOR SURVEILLANCE

Schistosomiasis is the second most prevalent tropical disease (following malaria) and a leading cause of severe morbidity in large parts of Africa, Asia and South America. 600 million are at risk; 200 million are infected, of whom 20 million are severely ill.

The main goal for WHO is to control the disease, to reduce and even (in some countries) eliminate the risk of schistosomiasis through strong surveillance and control programmes.

There are 2 types of clinical disease: urinary schistosomiasis (S. haematobium) and intestinal schistosomiasis (S. mansoni, S. japonicum, S. intercalatum, S. mekongi).

RECOMMENDED CASE DEFINITION

URINARY SCHISTOSOMIASIS

 

Case definition and classification

ENDEMIC AREAS (MODERATE OR HIGH PREVALENCE)

 

Suspected: Not applicable.

Probable: Not applicable.

Confirmed: A person with visible haematuria or with positive reagent strip for haematuria or with eggs of S. haematobium in urine (microscope).

 

NON-ENDEMIC AREAS AND AREAS OF LOW PREVALENCE

 

Suspected: A person with visible haematuria or with positive reagent strip for haematuria.
Probable: Not applicable.
Confirmed: A person with eggs of S. haematobium in urine (microscope).

 


INTESTINAL SCHISTOSOMIASIS

 

Case definition and classification

ENDEMIC AREAS (MODERATE OR HIGH PREVALENCE)

 

Suspected: A person with chronic or recurrent intestinal symptoms (blood in stool, bloody diarrhoea, diarrhoea, abdominal pains) or, at a later stage, hepatosplenomegaly.

Probable: A person who meets the criteria for presumptive treatment, according to the locally applicable diagnostic algorithms.

Confirmed: A person with eggs of S. mansoni, or S. japonicum/mekongi in stools (microscope).

 

NON-ENDEMIC AREAS AND AREAS OF LOW PREVALENCE

 

Suspected: A person with chronic or recurrent intestinal symptoms (blood in stool, bloody diarrhoea, diarrhoea, abdominal pains) or, at a later stage, hepatosplenomegaly.

Probable: Not applicable.

Confirmed: A person with eggs of S. mansoni or S. japonicum in stools (microscope).A person with positive reaction to immunoblot test.

 


RECOMMENDED TYPES OF SURVEILLANCE

Surveillance of schistosomiasis must be incorporated in the primary health care system.

For low-prevalence zones, and where eradication is targeted:

Routine monthly reporting of aggregated suspected or confirmed cases from peripheral level to intermediate and central level.

International: Yearly reporting from central level to WHO.

For endemic zones:

If no integration of surveillance is possible in the primary health care system: ad hoc surveys to evaluate the prevalence of infection in the community. Children of school age have been identified as a good indicator of prevalence in the general population and therefore an appropriate group for investigation.

Yearly reporting of aggregated data from peripheral level to intermediate and central levels.

 

Note: Data from general health statistics often underestimate prevalence but may nevertheless indicate a relatively high prevalence in a particular area.

Surveillance has to take into account the distribution of the disease in geographical foci. Adjacent areas may have very different prevalence rates.

RECOMMENDED MINIMUM DATA ELEMENTS

FOR LOW-PREVALENCE ZONES, AND WHERE ERADICATION IS TARGETED

Individual patient record for investigation

Identification number, age, place of infection, date of diagnosis, village.

Number of eggs per gram of stools/ml of urine.

Aggregated data

 

Number of cases by age group and village and month.
Number of cases with ≥50 eggs/10 ml of urine and/or visual haematuria (S. haematobium).
Number of cases with ≥400 eggs/g of stools (S. mansoni or S. japonicum).

FOR ENDEMIC ZONES

Aggregated data

 

Number of cases by age group and village.
Number of cases with ≥50 eggs/10 ml of urine and/or visual haematuria (S. haematobium).
Number of cases with ≥400 eggs/g of stools (S. mansoni or S. japonicum).

RECOMMENDED DATA ANALYSES, PRESENTATION, REPORTS

 

• Incidence (if passive reporting or passive surveillance) monthly and yearly by age group and village
• Point prevalence (if active finding)
• Mapping

PRINCIPAL USES OF DATA FOR DECISION-MAKING

 

• Assess the magnitude of the problem

• Plan drug distribution: establish treatment strategies in health services (diagnostic algorithims), select most cost-effective strategy for community-based chemotherapy (universal-targeted-selective)

• Evaluate the need for snail control

• Evaluate the need for improved water supply and sanitation

• Evaluate the need for health education activities

• Evaluate the impact of intervention

SPECIAL ASPECTS

 

• Diagnosis: quantitative diagnostic methods (Kato-Katz technique for intestinal forms, urine filtration for S. haematobium) are very important in surveillance; they indicate the public health relevance of the infection

• Collection of data immediately relevant to management decision (e.g., treatment frequency and resource allocation) should be encouraged

• Intersectoral efforts, emphasizing school education, safe water supply and sanitation, environmental management and community participation are important

• Rectal biopsy is usually not used for surveillance purpose

CONTACT

Regional Offices

See Regional Communicable Disease contacts on section "Communicable disease contacts in Regional Offices".

Headquarters: 20 Avenue Appia CH-1211 Geneva 27, Switzerland

Communicable Diseases Prevention and Control (CPC)

 

E-mail: saviolil@who.ch /Surveillancekit@who.ch
Tel: (41 22) 791 2664
Fax: (41 22) 791 4869
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