The prevalence of infectious pulmonary tuberculosis (TB) has come down in the country, finds a nationwide survey conduced in 20 years, thanks to scaling up of directly observed DOTS therapy, high case detection and cures rates as well as improved socio-economic status ofpopulation.

The new survey titled “National tuberculosis disease-cum infection prevalence survey 2007-'09” was jointly conducted by National Tuberculosis Programme (NTP) of the government and ICDDR.B with supports of USAID, KNCB, WHO and the Global Fund.

“The overall prevalence of smearpositive TB was 79.4 per one lakh adults, which is significantly lower than previous survey results or the current estimates," read the summary of the survey, which is scheduled to be to be made public at a city hotel today.

The last nationwide survey was con-

ducted in 1987-88, when theTB burden among adults aged over 15 years was 910 per one lakh population. There were also some other regional surveys done in 1995,2001 and 2002, where ICDDR.B in its survey found the prevalence rate 95 per one lakh eight years ago.

“This wide variation might be due to the design of the study, sampling strategy and sampling adequacy including the quality of data collection,” said an epidemiologist who obtained a copy of the study before its today's formal dissemination.

The survey was conducted over 52,098 adults aged over 15 and nearly 18,000 children between 5 and 14 years in 20 urban and 20 rural clusters in 20 districts of the country. All the participants of the study submitted two sputum samples, which were examined by high quality fluorescence microscopy at ICDDR.B.

According to the new survey, a higher prevalence of TB was found in rural areas

than urban or semi-urban areas, while persistent higher prevalence among males was recorded compared to females in the country.

Nearly two-thirds oftheTB cases were found among the 45 plus age group, while over 80 percent cases recorded among married couples.

At least two, out of five, cases were identified farmers and day labourers, while the lesser the education the more the TB prevalence was recorded during the study done between2007 and 2009.

One of the important findings of this study is that the vulnerable population in Bangladesh are the elderly male (55 years or above), people with poor economic condition (monthly income less than Tk 3,000 and had no education) as shown in the table of the study.

“This has two meanings one of which is thatTB continues to affect the poorest segment of the society although it is known thatTB is a disease of the poor but it is again proved in the big study,” said Dr

Abdul Hamid Salim, immediate past country director of Damien Foundation Bangladesh (DFB), one of the two major components of the study.

Dr Salim, now in Dutch-based KNCB, told over email that more TB prevalence among elderly population is a good sign.

He says probably the infection transmission is under control because of extensive DOT network across Bangladesh. The young children are less infected and as such young people have less TB, he said.

But an epidemiologist in Dhaka said, “What is very strange in the study is that the urban population has less TB than the rural which looks a bit strange. 1 do not at all think thatTB services in urban is better than rural areas. Urban TB control still needs to be strengthened.”

Dr K Zaman of ICDDRB was the principal investigator of the survey, while Prof Dr Provat Chandra Barua was the chairman of the study steering committee.