Detección de anticuerpos contra Trypanosoma cruzi en pacientes multitransfundidos, Colombia / Detection of Trypanosoma cruzi antibodies in multitransfused patients in Colombia

Resumen Introducción. La enfermedad de Chagas es un problema de salud pública en Latinoamérica y, aunque la transmisión vectorial es la más importante, deben evaluarse otras formas de transmisión, como la de las transfusiones. Objetivo. Describir la prevalencia de infección con Trypanosoma cruzi en pacientes sometidos a múltiples transfusiones o multitransfundidos. Materiales y métodos. Se detectaron anticuerpos IgG contra T. cruzi mediante dos inmunoensayos en muestras tomadas de pacientes sometidos a múltiples transfusiones en cuatro hospitales de Bogotá y Medellín, Colombia. Se analizó la asociación de factores de riesgo conocidos y se calcularon las razones de momios (odds ratio, OR) con un intervalo de confianza de 95 % (IC) utilizando el programa Stata 11(tm). Resultados. Se evaluaron 479 muestras. La prevalencia de anticuerpos contra T. cruzifue de 1,88 % (nueve pacientes): cinco pacientes remitidos de oncohematología, dos de hemodiálisis, uno tenía talasemia y uno había sufrido pérdida súbita y abundante de sangre. No se halló ningún paciente con hemofilia que resultara positivo, ni relación de los factores de riesgo de infección asociados con la transfusión de componentes sanguíneos, como el número de transfusiones, la cantidad de unidades de sangre y el tipo de componente, con la presencia de anticuerpos anti-T. cruzi. Solo se encontró relación entre la infección con el virus de la hepatitis C y la presencia de anticuerpos anti-T. cruzi (OR=5,68; IC95% 1,36-23,63). Conclusión. La frecuencia de infección por T. cruzi hallada en este grupo de pacientes sugiere que el riesgo de infección por transfusiones en Colombia es bajo. No se encontró relación entre los factores de riesgo asociados con la transfusión y la presencia de anticuerpos anti-T. cruzi.

Abstract Introduction: Chagas disease is a public health problem in Latin America. Even though vector-borne infection is the most important transmission mode for this disease, other modes such as transfusions require evaluation. Objective: To describe the prevalence of T. cruzi infection in multitransfused patients. Materials and methods: We detected IgG antibodies against T. cruzi by two immunoassays in samples from multitransfused patients in four hospitals located in Bogotá and Medellín, Colombia. We analyzed the association with known risk factors, and we calculated the odds ratios (OR) with 95% confidence intervals using Stata 11(tm) statistical software. Results: In total, 479 samples were tested. Overall, T. cruzi antibody prevalence was 1.88% (nine patients). Five were onco-hematological patients, two were hemodialyzed, one had thalassemia, and one had suffered acute blood loss. We found no hemophilia patients. There was no association between known risk factors for transfusion-transmitted infection (such as the number of transfusion events, number of blood units and type of blood component) and the presence of anti-T. cruzi antibodies in this study. Only the hepatitis C virus infection showed a positive association with the presence of anti-T. cruzi antibodies (OR=5.68, 95% CI: 1.36-23.63). Conclusions: The results of this study showed a low frequency of T. cruzi infection in multitransfused patients, suggesting that the risk of transfusion infection in Colombia is low. Known risk factors for transfusion-related infection were not associated with the presence of anti-T. cruzi antibodies.

Prevalence, Geographical Distribution, Social Problems and Treatment of Thalassemia Patients.

A total of 700 beta thalassemia patients were gathered at the outdoor of the Hematology department of Medical College, Kolkata, attending during the period from January 2010 to December 2010. The data is generated by the interaction between them and their family members in presence of the physicians. Actual ethnic identities, place of residence, parity and sibship together with social stigma, if any, faced by the patient or by the member of the family and details of their treatment including transfusion history were noted down and reconfirmed from past records. The prevalence of thalassemia was found 70% among Hindus of which the 62.26% was contributed by castes like Maishya, Namasudra, Barga Kshatriya and Panda Kshatriya. The relative prevalence of subtypes of b-thalassemia was found to be 65% E-b thalassemia, 30% Homozygous b-thalassemia and 5% S-b thalassemia. The aboard of the 85.28% patients were found to be localised along banks river Hooghly and Ganga delta region and we can thus consider tentatively that this belt is a thalassemia zone in West Bengal. The maximum number of cases showed parity to be 1 and there was considerable amount of reproductive wastage. Regarding social stigma, 82.71% responded with no stigma. Early diagnosis and early onset of transfusion with chelation therapy was found to provide benefit for the patient reducing the total amount of transfusion needed per year and also restoring the quality of their life.

[Prevalence of hemoglobinopathies in premarriage individuals referred to Babolsar, Iran [2006-09]]

According to world health organization statistics, at least 5.2% of world population is carrier for a main hemoglobin disorder. Previous reports showed that more than 10% of people are carrier for beta-thalassemia Northern Iran. This study was done to determine the prevalance of hemoglobinopathies in premarriage individuals referred to Babolsar, Iran. This descriptive study was carried out on 8500 individuals [4200 women and 4300 men] whome were attended the thalassemia counseling program in Babolsar, North of Iran during 2006-09. After performing the CBC test, for those MCV and MCH were less than 80 and 27 respectively, Hemoglobin A2 was evaluated. Subjects whome were volunteers for more comprehensive tests, basic and acidic electrophoresis and genetic tests were applied, subsequently. 1200 [14.11%] subjects had low hematological indexes. 474 [5.57%] subjects had high HbA2 and were classified as beta-thalassemia carriers and 726 [8.54%] had normal HbA2 level and were classified as alpha-thalassemia carriers. 6 [1.2%] subjects were identified with HbF level more than 10 and were identified as carriers for beta-gene cluster deletion carrier. Also, 16 [3.2%] individuals had HbE, 16 [3.2%] had HbS, 4 had HbD and 4 had HbH [0.33% in 1200 and 0.047% in 8500 subjects]. Genetic study of 317 individuals for beta carriers and 145 subjects for alpha-carriers showed IVSII-1G>A [74.5%] in beta-globin and single gene deletion of 3.7 [47.5%] in alpha-globin genes were the most frequent mutations. This study showed that carriers for alpha-thalassemia [8.5%] are more frequent compared with beta-thalassemia [5.57%]. Also other hemoglobin variants included HbS, HbE, HbD or different beta-gene cluster deletions in the region are considerable and should be screened

Haemoglobinopathies in Greece: prevention programme over the past 35 years.

At present, prevention of thalassaemia and sickle cell disease is the only realistic approach to control the birth of new patients in countries having high numbers of carriers. This is fully justified because avoiding the birth of an ever increasing number of patients may allow a more effective use of the available resources in improving the management of the patients surviving today and alleviate the already overloaded public health system from the inevitable tremendous and ever increasing cost. Moreover, prenatal diagnosis may help couples at risk to have non-thalassaemic children. Greece is one of the countries where the mean frequency of carriers is approximately 7.5 per cent (population 11 million) and has set up a nationwide programme for carrier identification in the early seventies; this is provided through a dozen of specific Units attached to the major Blood Transfusion Services of the country, on a voluntary basis and free of charge. Spread of information through mass media, the schools, and other groups has greatly contributed in creating the necessary sensitization; obstetricians and antenatal Clinics are also instrumental to this effect. Prenatal diagnosis is offered centrally (Athens) and covers satisfactorily the estimated needs (500-600 annually); the total number has already exceeded 35,000. According to information obtained from the major paediatric hospitals all over the country, the number of thalassaemia major or SCD admitted for treatment over the last ten years has been around 15 yearly (instead of an estimate of 120-130).

Past, present & future scenario of thalassaemic care & control in India.

The first case of thalassaemia, described in a non-Mediterranean person, was from India. Subsequently, cases of thalassaemia were documented in all parts of India. Centres for care of thalassaemics were started in the mid-1970s in Mumbai and Delhi, and then in other cities. The parent's associations, with the help of International Thalassemia Federation, greatly helped in improving the care of thalassaemics. Obtaining blood for transfusion was difficult, but the Indian Red Cross Society and the parent's associations played a crucial role in arranging voluntary donations of blood. Chelation with deferoxamine was used sparingly due to the high cost. The Indian physicians conducted trials with deferiprone, and the drug was first approved and marketed in India. Deferasirox is also now being administered. Studies of physical and pubertal growth documented significant retardation, suggesting that generally patients receive inadequate chelation and transfusions. Bone marrow transplantation is available at a number of centres, and cord blood stem cell storage facilities have been established. Information about mutations in different parts of India is available, and ThalInd, an Indian database has been set up. There is a need to set up preimplantation genetic diagnosis and non-invasive prenatal diagnosis. It is argued that too much emphasis should not be placed on premarital screening. The focus should be on screening pregnant women to yield immediate results in reducing the burden of this disorder. Care of thalassaemia has been included in the 12th 5-year Plan of the Government of India. Many States now provide blood transfusions and chelation free of cost. Although inadequacies in care of thalassaemia remain, but the outlook is bright, and the stage is set for initiating a control programme in the high risk States.

Thalassaemia and glucose-6-phosphate dehydrogenase deficiency in sickle-cell disorder patients in Taiz, Yemen

A pilot study was conducted to determine the prevalence and haematological characteristics of the interaction between thalassaemia or/and glucose-6-phosphate dehydrogenase [G6PD] deficiency in patients with sickle-cell disorder [SCD] in Taiz city, Yemen, where the prevalence of sickle-cell trait [HbAS] is 8.2%. Blood samples were collected from 31 SCD patients. Complete blood count and haemoglobin electrophoresis, G6PD activity and serum ferritin were determined. Thalassaemia was found in 6 patients [19.4%] and G6PD deficiency [6 mild and 1 severe] was detected in 7 patients [22.6%] The frequency of thalassaemia and/or G6PD deficiency with SCD was high and this may have an effect on the seventy of the clinical course of SCD in Taiz. The study should be repeated with DNA analysis to define the nature of the globin gene defect and to clarify its role in the severity of SCD

[Lack of knowledge of being minor thalasemic is the main cause of major thalassemia incidence in Zahedan, the South-East of Iran]

Introduction: In spite of providing prenatal diagnoses [PND] procedures for Thalassemia, 148 new patients were added to the Thalassemic population of Zahedan from 2002 to 2010. This study aimed at identifying the occurrence causes of newly arrived Thalassemic patients

Methods: This retrospective descriptive study was carried out on 148 couples whose Thalassemic children were born after establishment of the PND center at 2002. The required data were collected using interviews and hospital records of the patients

Results: The results indicated that 81.6% of the parents of major cases had not undergone pre-marriage Thalassemia screening test. Also, 70.2% of the couples were not aware of their minor Thalassemia before having a Thalassemic child. Moreover, 71% of parents who had been diagnosed with minor Thallasemia did not attend the PND center due to lack of knowledge, late gestational age, husband's unwillingness, and lack of awareness about the importance of the problem. In addition, from the referred couples in the first stage, 50% did not come to the centre for second stage of diagnosis [sampling of the fetus] due to religious beliefs, husband's unwillingness, and mothers' ignorance

Conclusion: The results showed that the most important causes of new occurrences of Thalassemia include couples' refraining from taking pre-marriage Thalassemia screening tests and lack of knowledge about being minor thalassemic. Therefore, appropriate programs may hopefully reduce the new cases

Hemoglobin D [Hb D Punjab/ Los Angeles and Hb D Iran] and Co-Inheritance with Alpha- and Beta- Thalassemia in southern Iran

Hemoglobin-D [Hb D] is an uncommon structural hemoglobin variant, which is reported to be prevalent in north western India. There are only a few small series, of this entity in the literature. We report the largest single center experience on this entity from Iran. Between November 2002 and December 2010 as a result of screening premaritally for betathalassemia in Shiraz, Fars Province, Southern Iran, column chromatography, Hb electrophoresis, solubility test, and/or high performance liquid chromatography [HPLC], direct sequencing and restriction analysis were used for hemoglobinopathies and structural Hb variants. The data of 220 subjects with Hb D variants are analyzed in this report. These comprised of 180 carries of Hb D; 92 cases of Hb D Punjab/Los Angeles [beta 121[Glutamic acid -> Glutamine]] and 88 subjects with Hb D Iran [beta 22 [Glu- > Gln]], 3 homozygous cases for Hb D, 17 subjects with betathalassemia- Hb D, 12 with Hb D- alpha- thalassemia- 1, 3 homozygous Hb D- alpha thalassemia- 1 trait, one with Hb D Punjab - sickle cell anemia, and two with Hb D Iran/sickle cell anemia. The carriers of Hb D and homozygous cases for Hb D were not anemic and had normal red blood cell morphology, as they are not usually detected. If Hb D was inherited in combination with thalassemia, the subjects had mild anemia and in some of them, the spleen was palpable [1-2 cm]. Co-inheritance of alpha thalassemia and Hb D resulted in the slightly higher Hb level and lower Hb D level as compared to Hb D/ betathalassemia cases [Hb D 24-37% vs 57-88%]. Co inheritance of Hb D and sickle cell results was moderate to severe hemolytic anemia

Deferasirox: Oral, once daily iron chelator - An expert opinion.

Iron overload is a serious and potentially fatal condition that results from multiple blood transfusions required over a long period of time to treat certain types of anemias such as, that caused by β-thalassemia, sickle cell disease and myelodysplastic syndrome. Deferoxamine, which has been used since four decades as an iron chelator has limited efficacy due to its demanding therapeutic regimen, leading to poor compliance. Deferasirox, once daily oral iron chelator provides an effective alternative to Deferoxamine in the treatment of transfusional hemosiderosis. In this review, the role of Deferasirox as an ideal iron chelator has been discussed. Pubmed searches on Deferasirox were carried out for the same. Several studies demonstrated the safety and efficacy of Deferasirox in reducing iron burden in iron-overloaded patients with β-thalassemia, sickle cell anemia and myelodysplastic anemia. Thus, convenient, effective and tolerable chelation therapy with oral Deferasirox is likely to be a significant development in the treatment of transfusional iron overload, due to its ability to provide constant chelation coverage and the potential to improve compliance.

Epidemiology of HCV infection among thalassemia patients in Eastern Mediterranean countries: a quantitative review of literature

Hepatitis C infection [HCV] is the major co-morbidity in thalassemia patients; however, literature lacks data from many EMRO counties. There is also enormous heterogeneity in the available study results in this region, and distribution of HCV infection among these patients living in this region is still unknown. This study provides a comprehensive and reliable tabulation of available data on the epidemiological characteristics and risk factors for hepatitis C virus [HCV] infection in thalassemia patients in eastern mediterranean countries. A systematic review was carried out based on the computerized literature database. 95% confidence intervals of infection rates were calculated using the approximate normal distribution model. Pooled Odds ratios and 95% CI were calculated by fixed or random effects models. The heterogeneity was assessed by either Q or X[2] statistics. Publication bias was evaluated by either Harbor's modified or Egger's test. We identified 40 studies that fulfilled our inclusion criteria involving 8554 thalassemia subjects. Pooled HCV seroprevalence was 18% [95% CI 14-21], 45% [95% CI 43-48], 63% [95% CI 56-69] and 69% [95% CI 58-80] in Iran, Pakistan, Saudi Arabia and Egypt, respectively. Among Iranian thalassemia patients, splenectomy OR=4.1 [95% CI 1.5-11.2], high transfusion OR=3.5 [95% CI 1.8-7], high age OR=6.1[95% CI 1.2-31.2] and first transfusion before 1996 OR=7.6 [95% CI 4.7-12.3] were major risk factors of HCV infection. There are no data from many EMRO countries. Among major EMRO countries, Iran has the least seroprevalence of HCV infection among thalassemia patients. This underscores more advanced blood safety in this country compared with other countries with comparable population in this region

Thalassemia, iron and G6PD deficiency in Lor migrating nomad children, Southern Iran

Ferropenia and consequent iron deficiency anemia [IDA], beta-thalassemia, and glucose 6-phosphate dehydrogenase [G6PD] deficiency are three main common hematologic problems in Iran. This study was conducted on the prevalence of these problems in Lor migrating nomads ethnic group in southern Iran. From June to October 2006, the blood samples of 79 Lor migrating nomadic children including 53 [67.1%] male and 26 [32.9%] female were checked for iron indices and G6PD deficiency. The family history of favism, thalassemiaand, signs and symptoms in relation to anemia of participants were evaluated. RBC count, different types of Hb, Hct, MCV, MCH, MCHC, RDW, SI, TIBC and SF were determined immediately after blood sampling. Fourteen [17.7%] children had SF<12 ng/mL while the prevalence of this low serum ferritin was higher in females than males [19.2% vs. 17%]. The low hemoglobin [Hb] level had statistical correlation with the low serum ferritin level. Among all participants, the prevalence of G6PD deficiency was 10.1%, and all of them were male children. The prevalence of beta-thalassemia was 2.5% and all were male. The prevalence of IDA was 17.7%. Although IDA figure is less than those reported in other developing countries [25-35%]; but it shows that Lor tribes in southern Iran are still behind the health status of developed countries [5-8%]. Even the prevalence of beta-thalassemia is not very high, but regarding the devastating potential risk of Cooley's anemia; a careful performance of Iranian thalassemia program is recommended. It seems that G6PD deficiency is prevalent in Lor nomads, so establishment of educational programs and investigation on their dietary habits seem to be a good way to prevent the favism occurrence

Genetic disorders and malaria in Indo-China region.

High prevalence of malaria in Southeast Asia including Thailand is believed to be a major public health problem to the population in this area since time immemorial. Adaptation of the population in this area following the principle of natural selection coupled with genetic disorders can be expected. Some good examples for natural selection of malaria are the co-existence of high prevalence of thalassaemia as well as glucose-6-phosphate dehydrogenase deficiency. In this report, general aspects of some important genetic disorders and malaria in Indo-China area (Thailand, Laos, Cambodia, Myanmar, Vietnam, Yunnan and Manipur) are summarized and discussed.

The prevalence and causes of anemia during pregnancy in Maharaj Nakorn Chiang Mai Hospital.

OBJECTIVE: To determine the prevalence and causes of anemia during pregnancy in Maharaj Nakorn Chiang Mai Hospital. MATERIAL AND METHOD: The pregnant women were screened with hemoglobin, hematocrit, osmotic fragility test, hemoglobin E test and serology for hepatitis B, syphilis and HIV at first antenatal visit. In anemic cases, serum ferritin, serum iron/total iron binding capacity, or therapeutic trial with iron supplementation were performed to assess the iron status. The cases of abnormal thalassemia screening were followed by hemoglobin A2 level, PCR for alpha-1 (SEA type) and hemoglobin electrophoresis. Additional tests were stool exam, stool occult blood and red blood cell indices. Anemia was defined as a hemoglobin level less than 11.0 g/dl in the first and third trimester or less than 10.5 g/dl in the second trimester of pregnancy. The data was presented as mean, standard deviation and percentage. RESULTS: Six hundred and forty eight pregnant women were recruited. The prevalence of anemia was 20.1 percent (128 cases). Classified in each trimester the prevalence was 17.3%, 23.8% and 50.0% in the first, second and third trimester, respectively. Thalassemia carriers and diseases were detected in 56 from 102 anemic pregnant women (54.9%). Iron status was assessed in 58 cases and iron deficiency anemia was found in 25 cases (43.1%). Other causes of anemia were parasitic infection (8.7%) and anemia of chronic disease (2.7%). In 37 anemic pregnant women (33.0%), the causes of anemia were not found. CONCLUSION: The prevalence of anemia in pregnant women who first attended at the antenatal clinic was 20.1%. The main causes of anemia were thalassemia carriers/diseases and iron deficiency anemia.

Dengue hemorrhagic fever in patients with thalassemia.

Dengue hemorrhagic fever (DHF) causing by dengue viral infection is endemic in Thailand and Southeast Asian countries where thalassemias are prevalent. Thalassemic patients are also at risk to acquire dengue viral infections and to develop DHF. However, they can have different clinical manifestations and complications as well as more severity than general population requiring special awareness for proper diagnosis and management. We reported 20 thalassemic patients (10 boys and 10 girls) with DHF admitted to Department of Pediatrics, Siriraj Hospital during 1977 to 2001. Their ages ranged from 2-16 years (average 9.5 years). These cases included 5 cases of Hb H disease, 5 cases of Hb H with Hb Constant Spring (CS), 9 cases of beta-thalassemia/Hb E disease and 1 case of beta-thalassemia major. Two cases were in Grade I, 10 cases in grade II, 7 cases in Grade III and one case in grade IV severity of DHF. Though there were evidences of plasma leakage, instead of hemoconcentration, eighteen patients (90 percent) had hematocrit dropped at the range of 11-66% of the initial level. Fifteen patients (75 percent) required at least one packed red cell transfusion. Nine patients (45 percent) had mild bleeding symptoms, one of them had upper gastrointestinal hemorrhage requiring platelet concentrate transfusion. Two patients (10 percent) had serious complications including one with infection-associated hemophagocytic syndrome (IAHS) requiring intravenous immunoglobulin (IVIG) and packed red cell transfusion and the other had generalized seizure due to hyponatremia and hypotension. No mortality was observed among this group of patients. Early recognition of the DHF in thalassemic patients and appropriate packed red cell transfusion in patients with anemic symptoms is warranted to reduce morbidity and mortality in these patients.

Prevalence of thalassemia in pregnant women at Maharaj Nakorn Chiang Mai Hospital.

OBJECTIVE: To determine the prevalence of thalassemia including alpha-thalassemia-1 trait (SEA type), beta-thalassemia trait, hemoglobin E (HbE) trait, homozygous HbE, the combination of alpha-thalassemia-1 (SEA type) and beta-thalassemia trait, alpha-thalassemia-1 (SEA type) and hemoglobin E trait, and beta-thalassemia hemoglobin E disease in pregnant women. METHOD: A cross-sectional descriptive study was conducted on pregnant women who attended the antenatal clinic at Maharaj Nakorn Chiang Mai Hospital, from 1 August to 31 October 2001. All subjects had blood taken for diagnosis of thalassemia trait or diseases, based on quantitative electrophoresis, and PCR (polymerase chain reaction) technique RESULTS: 516 pregnant women were recruited 81.0% resided in Chiang Mai province, and the remainder were in other northern provinces of Thailand. The mean (+/-SD) age was 27.7+/-6.3 years old. 5.6% of cases had anemia. Overall prevalence of thalassemia trait was 25.4% which were classified as follows: alpha-thalassemia-1 (SEA type) trait 6.6%, beta-thalassemia trait 3.7%, hemoglobin E trait 11.6%, homozygous hemoglobin E 0.8%, the combination of alpha-thalassemia-1 (SEA type) and beta-thalassemia trait 1.2% and the combination of alpha-thalassemia-1 (SEA type) and hemoglobin E trait 1.5%. Additionally, the authors also found beta-thalassemia hemoglobin/E disease 0.2%. CONCLUSION: The prevalence of thalassemia carriers among pregnant women at Maharaj Nakorn Chiang Mai hospital was high, indicating the necessity of a screening thalassemia program aimed at prevention and control of this disease.

Prevention of thalassemia: experiences from Samui Island.

Thalassemia is one of the most important genetic disorders in Thailand. A model for prevention of thalassemia by combining 4 strategies including education, carrier screening, counseling and prenatal diagnosis was developed by a thalassemia task force. A thalassemia work group was formed in order to develop a mechanism to integrate the model for real use on Samui Island where thalassemia is common and a specific disease oriented program is required. 200 health professionals working on Samui Island participated in the thalassemia educational courses. The specific training courses were also provided for obstreticians, medical technologists and counselors. A team of well-trained health professionals was established to manage public education. Information booklets, posters, brochures and mass media including spot radio and newspapers were used as educational materials. For carrier screening, blood samples of pregnant women from all health care organizations on Samui Island were collected and screened for thalassemia carriers by using the osmotic fragility (OF) test/the dichlorophenol indophenol precipitation (DCIP) tests at Samui Hospital. Samples with positive results were sent to the Regional Medical Sciences Center in Surat Thani for thalassemia diagnosis. When a carrier was identified, her spouse was offered testing. For at-risk couples, details of the disorder were included in counseling to help them reach a decision that was right to them, in the context of their unique medical, moral and social situations. Amniotic fluid samples were collected for prenatal diagnosis. All patient information was registered by using computer software. After 1 year of integration by using facilities of the Ministry of Public Health service system, a wide range of problems were identified. They underlined the need for effective health service structure co-operation, adequate education of responsible health professionals, explicit policies and a clear line of responsibility at local, regional and national levels for service development and quality management. It is hoped that all information conducted in the present study will be useful to health authorities to develop an explicit policy and promote the health service structure co-operation in the country that will finally lead to successfully reducing the frequency of severe thalassemia in the future.

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.