A community-based thalassemia prevention and control model in northern Thailand.

OBJECTIVE

To describe a community-based model for prevention and control of thalassemias and haemoglobinopathies in northern Thailand.

DESIGN

Operational research composed of two components. First, a model to test whether thalassemic cases and carriers could be retrospectively detected from school children. Second, a model for prevention of prospective cases of thalassemic babies among pregnant women.

SETTING

Phan District of Chiang Rai Province in northern Thailand.

SUBJECTS

Component one: 5,617 preschool children and 21,123 school children were screened during May and July 1997. Component two: 256 pregnant women, 16 weeks or less gestation were screened during January and December 1997.

MATERIAL AND METHOD

Component one: Sub-district public health officers and school teachers were trained to use pictures and simple clinical examination to detect suspected thalassemics among preschool and school children. Suspected cases were then referred for further clinical examination and blood testing. Blood smear examination was done at the Phan Community Hospital but Hb typing lusing on electrophoresis was done at the provincial hospital. The cellulose acetate was sent for re-reading at the Department of Medical Sciences. Component two: Osmotic fragility (OF) and dichlorophenol-indolephenol (DCIP) tests were abol in pregnant women (< or = 16 weeks of gestation) in the Phan Community Hospital. If OF test was positive, Hb typing was done at a regional medical sciences center. Their spouses were also located and tested for Hb typing. Prenatal diagnosis was done and therapeutic abortion was offered, if indicated.

MAIN OUTCOME MEASURES

Cases, carriers, suspected cases, Hb typing, OF and DCIP tests.

RESULTS

In Component one: 26,740 children were screened of whom 893 cases were suspected. Out of those suspected, 296 (33.2%) were normal, 140 (15.6%) were diseased, and 457 (51.2%) were carriers. 56 cases had major thalassemia diseases. Their parents were counseled. Forty couples were determined to need some form of family planning and 39 (97.5%) accepted. In Component two: 256 pregnant women were screened and 56 were found to be carriers. Only 45 husbands could be located and Hb typed. Five couples were determined to require prenatal diagnosis (PND). One happened to undergo therapeutic abortion because of HIV infection in the mother without PND. Of the four who underwent PND, one was found to have a fetus with major thalassemia. However, this couple refused therapeutic abortion because of religious reasons.

CONCLUSION

This study combined both prospective and retrospective approaches and can be considered successful. However, as the only available option for pregnant women with affected fetuses is therapeutic abortion, this makes it difficult to expand the program because abortion may not be acceptable in certain communities. In addition, this model requires PND and other laboratory and clinical facilities as backups. Such backups may not be available in certain settings.