PREGUNTA DE INVESTIGACIÓN ¿Cuál será la frecuencia de anemia en escolares de 13 a 18 años de edad y su relación con el rendimiento escolar en la ciudad de La Paz durante la gestión 2006? OBJETIVO Conocer la frecuencia de anemia en escolares de 13 a 18 años de edad de escuelas privadas y su relación con el rendimiento escolar. DISEÑO DE LA INVESTIGACIÓN Diseño de Corte Transversal. LUGAR Unidad de Epidemiología Clínica (laboratorio de hematología) del Instituto de Investigación en Salud y Desarrollo (IINSAD) y colegios particulares de la ciudad de La Paz. POBLACION 200 niños escolares adolescentes de 13 a 18 años de edad, de distinto sexo, de colegios particulares de la ciudad de La Paz. METODOS Previo al procedimiento, se obtuvo el consentimiento de los padres o tutores para participar en el estudio. Para cada uno de los pacientes se llenó un cuestionario con datos personales, edad, sexo y el promedio general de notas, se realizó un examen físico general y se tomó una muestra de sangre capilar en tubos capilares con anticoagulante en cada uno de los pacientes. Se realizó pruebas hematológicas específicas de la serie roja, obteniendo valores de hematocrito, hemoglobina, grupo sanguíneo y factor Rh. RESULTADOS El promedio de edad es 15.43 años, 51.5% mujeres (n: 103) y 48.5% varones (n: 97). El valor de hematocrito en varones presenta un promedio de 50.8% SD 3.48 IC 95%(50.2-51.6), en mujeres Hto 47% SD 2.79 IC 95%(46.5-47.6). La mediana (percentil 50) del hematocrito fue mayor en varones que en mujeres. La hemoglobina, presentó un promedio en varones de 16.06 g/dl SD. 1.09, IC 95%.(15.7-16.1) , en mujeres un promedio de 14.71 SD 1.07, IC 95% (14.6-15.1). En cuanto a la distribución de grupos sanguíneos se presenta un 66,5% para el grupo "O", grupo "A" 23.5%; Grupo "B" 9%, grupo AB 1% y para el factor Rh positivo 98.5% (n=197) y para el factor Rh negativo 1.5% (n=3). Para observar la relación entre el promedio de hemoglobina y el rendimiento escolar encontramos un valor p > 0.6746. CONCLUSIONES Con los resultados obtenidos en este grupo de estudio se concluye que la frecuencia de anemia es de 13.5 %, y no tiene asociación significativa con el rendimiento escolar. La frecuencia de grupos sanguíneos se encuentran con diferencias en relación a los datos reportados en el pasado.

RESEARCH QUESTION What is the frequency of anemia in school children from 13 to 18 years of age and its relationship with academic achievement in school in La Paz during the year 2006? OBJECTIVE To assess the frequency of anemia in school children from 13 to 18 years of age and its relationship with academic achievement in school. DESIGN Descriptive, cross sectional study. PLACE Unit of Clinical Epidemiology (hematology laboratory) of the Institute of Investigation in Health and Development (IINSAD) and private schools of La Paz. PARTICIPANTS 200 adolescent school children 13 to 18 years old, of both sexes, of private schools in La Paz. METHODS Previous to the procedure, the consent of the parents or tutors was obtained for participation in the study. For each one of the children a questionnaire was filled out with personal information, like age, sex and the general grade point average, a general physical exam was performed and a sample of capillary blood was taken in capillary tubes with anticoagulant. Specific hematologic tests of the red series were carried out, obtaining hematocrit values, hemoglobin, blood group and Rh factor. RESULTS The average age was 15.43 years, 51.5% of the children were females (n: 103) and 48.5% males (n: 97). The average hematocrit of males was 50.8%, SD 3.48, IC 95%, and of females 47%, SD 2.79, IC 95%. The mean (percentile 50) hematocrit was grater in males than in females. The average hemoglobin in males was 16.06 g/dl, SD. 1.09, IC 95%., in females 14.71, SD 1.07, IC 95%. The distribution of the blood groups is shown in Fig.2, 98.5% (n=197) were Rh positive and 1.5% (n=3) Rh negative. The general grade point average was 48.51. For the relationship between hemoglobin average and academic achievement we found a p value > 0.6746. CONCLUSIONS From the statistical analysis of significance we conclude that there does not exist a significant relationship between anemia and academic achievement in this population group.

A cross section of a human population (501 individuals) selected at random, and living in a Bolivian community, highly endemic for Chagas disease, was investigated combining together clinical, parasitological and molecular approaches. Conventional serology and polymerase chain reaction (PCR) indicated an active transmission of the infection, a high seroprevalence (43.3%) ranging from around 12% in < 5 years to 94.7% in > 45 years, and a high sensitivity (83.8%) and specificity of PCR. Abnormal ECG tracing was predominant in chagasic patients and was already present among individuals younger than 13 years. SAPA (shed acute phase antigen) recombinant protein and the synthetic peptide R-13 were used as antigens in ELISA tests. The reactivity of SAPA was strongly associated to Trypanosoma cruzi infection and independent of the age of the patients but was not suitable neither for universal serodiagnosis nor for discrimination of specific phases of Chagas infection. Anti-R-13 response was observed in 27.5% only in chagasic patients. Moreover, anti-R13 reactivity was associated with early infection and not to cardiac pathology. This result questioned previous studies, which considered the anti-R-13 response as a marker of chronic Chagas heart disease. The major clonets 20 and 39 (belonging to Trypanosoma cruzi I and T. cruzi II respectively) which circulate in equal proportions in vectors of the studied area, were identified in patients' blood by PCR. Clonet 39 was selected over clonet 20 in the circulation whatever the age of the patient. The only factor related to strain detected in patients' blood, was the anti-R-13 reactivity: 37% of the patients infected by clonet 39 (94 cases) had anti-R13 antibodies contrasting with only 6% of the patients without clonet 39 (16 cases).

Previous studies showed that two groups of Trypanosoma cruzi clonal genotypes named clonet 20 and clonet 39 were predominant in Triatoma infestans, the unique vector of Chagas disease in Bolivia. These groups of clones correspond to distinct genetic clusters. These clonets were detected in T. infestans and Rhodnius pictipes fecal samples before isolation and after culture by kDNA PCR (polymerase chain rreaction) and hybridization of the amplified products with clonet specific kDNA probes named 20 and 39 as previously reported. Forty eight T. infestans and three R. pictipes infected insects captured at random in different Bolivian departments were proceeded. As previously reported the direct identification of the two major clonets in fecal samples allowed the detection of abundant mixed infections: 41% in the original sample, however after culture, only 6% of mixed infections were detected. Among the 21 parasite stocks isolated from digestive tracts where mixed infections were initially detected (clonet 20 + 39) clonet 20 alone was detected in 81% of them. This result clearly showed that the culture step selected clonet 20 parasites over those belonging to clonet 39. The taxonomic status of the isolated stocks was also confirmed by isoenzyme typing, and correlation was observed between clustering topology and hybridization patterns with the probes 20 and 39.