Sunday, February 06, 2011

Estimation of Annual Risk of Tuberculosis Infection in Sri Lanka: an epidemiological approach for assessing the TB situation in the country.

Wijesinghe PR, Palihawadana P, Alwis S.

Methodology: A nation wide, school-based, cross sectional tuberculin survey was conducted to estimate the Annual Risk of Tuberculosis Infection (ARTI). The study sample comprised 5280 children aged 10 years irrespective of the BCG vaccination selected in a stratified, two stage cluster sampling technique. Of these, 4352 were administered tuberculin and reactions were read in 4202 within 72 hours according to a standardised protocol.

Results: The proportion immunized with BCG was 98% and 95% had a BCG scar. Frequency distribution of reactions demonstrated a not very distinct second mode corresponding to 15mm.Therefore; the mode of reaction sizes observed among 82 smear positive cases (20mm) was also studied. Both modes were used as cut off values for determining prevalence of TB by mirror image technique and ARTI as scenario one and two.

The national estimate of ARTI was 0.4% (95% CI- 0.2-0.7%) (Scenario I) and 0.12% ( 0.07-0.17%) (Scenario II). The corresponding values for urban, rural and estate strata were 1.4% (95CI- 0.8-2.1%), 0.2% (95CI- 0-0.6%) and 0.2 %( 95 CI- 0-0.7%) respectively, according to the scenario I. According to scenario II, ARTI estimates were 0.6% (95CI-0.08-1.2%) for urban, 0.12 %( 95CI- 0.07-0.2%) for rural, and 0.05% (95% CI- 0-0.2%) for estate sectors.

Conclusions: The national estimate of ARTI reflected a low risk of TB transmission. This estimate was lower than the same for many developing countries and higher than that for industrialised countries. ARTI in the urban stratum was higher than the national estimate.

The high ARTI in the urban sector calls for strengthening and intensifying TB control activities on sustained and long term basis. The low risk in other sectors does not allow complacency as reported incidence rate at present is less than the expected incidence of newly infected and re infected individuals .Sustained, committed , long term provision of quality anti tuberculosis service remains essential. A repeated tuberculin survey is recommended in 5-7 years for epidemiological trend analysis.

Participatory approach to control intestinal infections in different socio economic and cultural settings in Sri Lanka

by Jayasinghe A, Wijesinghe PR.

Introduction:Intestinal infections endemic in one geographical area may cause outbreaks in other parts of the country. The common disease control strategies are not effective when applied uniformly in all areas as practices of inhabitants differ in different socio cultural and economical settings. Therefore, ascertaining knowledge, practice and behaviours of inhabitants and strategic planning with available resources are effective ways for disease control.

• To identify behavioural and administrative factors affecting control of intestinal diseases
• To design, implement, monitor and evaluate locality specific programs through participatory approach to control intestinal infections
• To prepare a comprehensive, national intestinal disease control program incorporating different locality specific programs

Methods :Six different groups of people in different localities were identified based on routine surveillance data on intestinal infections. These groups were Tamil speaking tea estate community in Badulla, Tamil and Sinhala speaking vegetable farmers from Nuwareliya district, Faddy cultivators from Anuradapura district, Moor community in Puttalam district and a seasonal migrant fishing community from an islet in Puttalam district and a Tamil speaking, semi urban community in Mannar district. Based on focus group discussions with inhabitants and on-site situational analysis, six different intestinal disease control programs were worked out with stakeholders through a participatory approach. Activities were monitored for a period of 12 months.

Results ;Though the knowledge on control measures of intestinal diseases was adequate, behaviours and practices were not satisfactory for controlling the disease. The priority given by divisional health authorities for surveillance and control of intestinal diseases were not up to the expected level. Available resources were proved to be adequate to reduce disease incidence by 50% when area specific problems were prioritised by the divisional health authorities and responsibility was shouldered by different stakeholders.

A generic control program is not recommended for different socio-cultural groups. Locality specific disease control programs prepared through a participatory approach by divisional stakeholders is the best approach for effectiveness and sustainability of practical control programs.
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