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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
 

A15-A19 Tuberculosis

RATIONALE FOR SURVEILLANCE

About one-third of the world's population is infected by Mycobacterium tuberculosis. Between 7 and 8.8 million new cases occur each year, 95% in developing countries; some 3.3 million cases of tuberculosis are notified each year. Projections into the next century suggest that the impact of tuberculosis will increase if no adequate control is established immediately in all countries.

The overall objective of tuberculosis control is to reduce morbidity, mortality and transmission of the disease until it no longer poses a threat to public health. To achieve this objective, the 1991 World Health Assembly endorsed the following targets for global tuberculosis control:

 

• successful treatment for 85% of the detected new smear-positive cases

• detection for 70% of smear-positive cases by the year 2000


Surveillance of tuberculosis helps to monitor the course of the tuberculosis epidemic, and patient cohort analysis is used to evaluate treatment outcomes.

RECOMMENDED CASE DEFINITIONS

DEFINITIONS OF WHO/IUATLD
(INTERNATIONAL UNION AGAINST TUBERCULOSIS AND LUNG DISEASES)

1. Site and bacteriology

Pulmonary tuberculosis, sputum smear positive (PTB+)

 

• Tuberculosis in a patient with at least two initial sputum smear examinations (direct smear microscopy) positive for Acid-Fast Bacilli (AFB), or

• Tuberculosis in a patient with one sputum examination positive for acid-fast bacilli and radiographic abnormalities consistent with active pulmonary tuberculosis as determined by the treating medical officer, or

• Tuberculosis in a patient with one sputum specimen positive for acid-fast bacilli and at least one sputum that is culture positive for acid-fast bacilli.


Pulmonary tuberculosis, sputum smear negative (PTB-)

Tuberculosis in a patient with symptoms suggestive of tuberculosis and having one of the following:

 

• Three sputum specimens negative for acid-fast bacilli

• Radiographic abnormalities consistent with pulmonary tuberculosis and a lack of clinical response to one week of a broad-spectrum antibiotic

• Decision by a physician to treat with a full curative course of anti-tuberculous chemotherapy

Pulmonary tuberculosis, sputum smear negative, culture positive

Tuberculosis in a patient with symptoms suggestive of tuberculosis and having sputum smear negative for acid-fast bacilli and at least one sputum that is culture positive for M. tuberculosis complex

Extra-pulmonary tuberculosis

 

• Tuberculosis of organs other than lungs: pleura, lymph nodes, abdomen, genito-urinary tract, skin, joints and bones, tuberculous meningitis, etc.

• Diagnosis should be based on one culture positive specimen from an extra-pulmonary site, or histological or strong clinical evidence consistent with active extra-pulmonary tuberculosis, followed by a decision by a medical officer to treat with a full course of anti-tuberculous therapy

• Any patient diagnosed with both pulmonary and extra-pulmonary tuberculosis should be classified as a case of pulmonary tuberculosis

2. Category of Patient

New case: A patient who has never had treatment for tuberculosis or took anti-tuberculous drugs for less than 4 weeks.

Relapse case: A patient previously treated for tuberculosis and declared cured by a medical officer after one full course of chemotherapy, but who reports back to the health service bacteriologically positive (smear or culture).

In addition to these definitions, European countries also report cases as "definite" (confirmed by culture of M. tuberculosis complex or by sputum smear examinations positive for acid-fast bacilli) or "other than definite" (based on a clinician's impression of symptoms, signs and radiological findings and decision to treat the patient with a full course of anti-tuberculosis treatment).

RECOMMENDED TYPES OF SURVEILLANCE

Registration of diagnosed cases at district level.

Quarterly reports on case notifications and cohort analysis of treatment outcomes (at peripheral, intermediate, and central level).

RECOMMENDED MINIMUM DATA ELEMENTS

Case notifications by category

 

• Number of new pulmonary sputum smear positive cases

• Number of pulmonary relapse cases

• Number of new pulmonary sputum smear negative cases

• Number of new extra-pulmonary cases

• Number of new pulmonary sputum smear positive cases by age and gender (suggested age groups: 0-14,15-24, 25-34, 35 - 44, 45-54, 55-64, 65+ years)

Treatment results for new sputum smear positive cases:

(usually as a percentage of all new sputum smear positive cases registered during the same period of time):

 

• Number of cases who converted to negative after initial phase of treatment

• Number of cases cured (i.e., completed treatment and at least 2 negative sputum smear results during the continuation phase of treatment, one of which occurred at the end of treatment)

• Number of cases who, after smear conversion at the end of initial phase of treatment, completed treatment, but without smear results at the end of treatment

• Number of cases who died (regardless of cause)

• Number of cases who failed treatment (i.e., became positive again or remained smear positive, 5 months or more after starting treatment).

• Number of cases who interrupted treatment/defaulted (i.e., did not collect drugs for 2 months or more after registration)

• Number of cases who were transferred out (i.e., transferred to another reporting unit and results not known)

 

Note: In countries routinely using culture as a diagnostic tool, the treatment results may be based on a second culture obtained during the continuation phase of treatment.

RECOMMENDED DATA ANALYSIS, PRESENTATION, REPORTS

Analysis of geographical area (district) quarterly reports

Treatment success rate: number of cases cured, plus patients who completed treatment, as a ratio of all cases registered during the same period of time

Quality of diagnostic services: ratio of new sputum-smear positives to all pulmonary cases

Presentation and reports Graphs:

 

• Case notification rates over several years by geographical area, regions, country.

• Case notification rates (new sputum smear positives) by age and sex

• Case detection rate: ratio of the tuberculosis cases detected by the national tuberculosis control programme to the number of cases estimated to have occurred in the country


Tables:

Describe quarterly reports by case finding and treatment outcomes.

PRINCIPAL USES OF DATA FOR DECISION-MAKING

 

• At local level: ensure that appropriate treatment services are offered, contact tracing is carried out, local outbreaks are recognized, and local epidemiology is monitored

• At national level: facilitate monitoring of the epidemiology of the disease and of the performance of treatment programmes (ability of a National Tuberculosis Programme to detect tuberculosis cases, diagnose sputum positive cases, treat tuberculosis cases successfully); and facilitate planning for programme activities (e.g., securing drug supply, lab supply, etc.)

 

• At international level: examine trends over time and make inter-country comparisons with the aim of coordinating control efforts

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 Surveillance (CDS)

 

E-mail: outbreak@who.ch / Surveillancekit@who.ch
Tel: (41 22) 791 2598
Fax: (41 22) 791 4199
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