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.

Saturday, January 01, 2011

Don’t panic, say health officials

News ( Sundaytimes Sunday November 14, 2010 )

As the second wave of A/H1N1 hit the country, taking on the pattern of a seasonal influenza or flu, health officials urged the public not to panic.

So far there have been 48 confirmed cases since October 6, when the first patient of the second wave was detected in the influenza-like disease surveillance at the Lady Ridgeway Hospital for Children in Colombo, Consultant Epidemiologist Dr. Ranjan Wijesinghe of the Epidemiology Unit told the Sunday Times.

Stressing that the World Health Organization (WHO) has now declared that H1N1 is in the ‘post-pandemic period’ or last phase, he explained that this, however, does not mean that we will not have cases. The virus will continue to circulate for many more years, but the severity will be less.

The important difference between the first wave that hit Sri Lanka in June last year during the ‘pandemic phase’ and the second wave this year is that the virus has joined the pattern of other seasonal flu viruses, he said, adding that H1N1 was the predominantly circulating strain in the first wave.

“Then it spread like wildfire, with people manifesting severe symptoms but now we may not see an unusual breakout. This is because some people have acquired immunity against H1N1 either due to contracting the virus or being vaccinated against it. But it will be seen among clusters of people who are not immune,” he said.

Among those who develop the disease, the individuals who have co-morbidities or health issues such as hypertension and diabetes which make them immune-deficient, may have severe symptoms, said Dr. Wijesinghe.

“Therefore, it is important to think about remedial measures, with the best option being vaccination,” he said. The vaccines have been distributed to all Medical Officers of Health (MOHs) to be administered to those with the highest risk of catching H1N1 such as health and disaster management workers as well as essential services which include armed service personnel and telecom and electricity workers, the Sunday Times learns.

Anyone with health issues which may make them vulnerable to the virus may also seek the flu shot from the MOH, he said.

The second wave was anticipated following trends in countries in the Southern Hemisphere such as Australia and New Zealand where H1N1 distinctly joined the bandwagon during the flu season. Our surveillance data since 2004 has indicated that we have flu throughout the year but with two major peaks in February-March-April and October-November-December, he said, explaining that with the first wave peaking in the middle of October last year, H1N1 was expected to act similarly this year. This was further strengthened by the fact that cases are occurring in the southern Indian states of Andhra Pradesh, Tamil Nadu and Kerala with much travel between them and Sri Lanka.

In the first wave which hit in June last year with imported cases and the community spread beginning in October and continuing until mid-February this year there were 642 confirmed cases with 48 deaths.
The fortunate factor was that in the first wave only 10% of those who contracted H1N1 needed intensive care unit admission which indicates that the virus virulence was not so bad, he added.

Friday, June 04, 2010

Estimation of the Annual Risk of TB in Sri Lanka: Presentaion made at the EPISEA 10th scientific session in Colombo

Tuesday, May 18, 2010

Surveilance of Inflenza in Sri Lanka- presentation made at the Indian Influenza Society meeting at New Delhi, 2009

Thursday, May 13, 2010

Transition from killed JE vaccine to Live JE vaccine : Sri Lankan experience ( presentation for the Bi regional meeting on JE 2009)

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