Liliana Jazmín Cortés

Asymptomatic Plasmodium spp. infection in Tierralta, Colombia

With the aim of determining the prevalence of asymptomatic Plasmodium spp. infection by thick smear and PCR and its association with demographic and epidemiological characteristics in the village of Nuevo Tay, Tierralta, Córdoba, Colombia, a cross-sectional population study was carried out, using random probabilistic sampling. Venous blood samples were taken from 212 people on day 0 for thick smear and PCR. Clinical follow-up and thick smears were carried out on days 14 and 28. The prevalence of Plasmodium spp. infection was 17.9% (38/212; 95% CI: 12.5-23.3%) and the prevalence of asymptomatic Plasmodiumspp. infection was 14.6% (31/212; 95% CI: 9.6-19.6%). Plasmodium vivax was found more frequently (20/31; 64.5%) than Plasmodium falciparum (9/31; 29%) and mixed infections (2/31; 6.5%). A significantly higher prevalence of asymptomatic infection was found in men (19.30%) than in women (9.18%) (prevalence ratio: 2.10; 95% CI: 1.01-4.34%; p = 0.02). People who developed symptoms had a significantly higher parasitemia on day 0 than those who remained asymptomatic, of 1,881.5 +/- 3,759 versus 79 +/- 106.9 (p = 0.008). PCR detected 50% more infections than the thick smears. The presence of asymptomatic Plasmodium spp. infection highlights the importance of carrying out active searches amongst asymptomatic populations residing in endemic areas.

Paradoxical associations between soil-transmitted helminths and Plasmodium falciparum infection

Evidence on the comorbidity between soil-transmitted helminth infections and malaria is scarce and divergent. This study explored the interactions between soil-transmitted helminth infections and uncomplicated falciparum malaria in an endemic area of Colombia. A paired case-control study matched by sex, age and location in Tierralta, Cordoba, was done between January and September 2010. The incident cases were 68 patients with falciparum malaria and 178 asymptomatic controls. A questionnaire was used to gather information on sociodemographic variables. Additionally physical examinations were carried out, stool samples were analysed for intestinal parasites and blood samples for Ig E concentrations. We found associations between infection with hookworm (OR: 4.21; 95% CI: 1.68-11.31) and Ascaris lumbricoides (OR 0.43; 95% CI: 0.18-1.04) and the occurrence of falciparum malaria. The effects of soil-transmitted helminths on the occurrence of malaria were found to be paradoxical. While hookworm is a risk factor, A. lumbricoides has a protective effect. The findings suggest that, in addition to the comorbidity, the presence of common determinants of soil-transmitted helminth infections and malaria could also exist. While the biological mechanisms involved are not clear, public health policies aimed at the control of their common social and environmental determinants are suggested.

Concordancia entre ELISA e IFI para la determinación de anticuerpos tipo IgG contra Toxoplasma gondii

Resumen Objetivo Medir el grado de concordancia entre las tecnicas de inmunofluorescencia indirecta y de ELISA, empleadas para la deteccion de anticuerpos IgG anti-Toxoplasma gondii en humanos. Materiales y metodos Se llevo a cabo un estudio descriptivo comparativo de dos tecnicas diagnosticas para la deteccion de anticuerpos IgG anti-T. gondii, en 243 sueros humanos del banco de muestras del Laboratorio de Parasitologia-Red Nacional de Laboratorios del Instituto Nacional de Salud, recolectados durante los anos 2000 a 2006. Resultados El porcentaje de reactividad para la deteccion de anticuerpos IgG anti-T. gondii fue de 54% (131 sueros) por la tecnica IFI y de 56,3% (137 sueros) por la tecnica ELISA; ademas, el 46% (112 sueros) de las muestras fueron negativas por la tecnica IFI y el 44% (106 sueros) negativas fueron por la tecnica ELISA. El valor del indice kappa fue de 0,916 (IC95% 0,866–0,976), el cual refleja una concordancia casi absoluta entre las dos tecnicas. Conclusiones El indice kappa muestra una concordancia casi absoluta entre las tecnicas, IFI y ELISA, lo cual hace que los laboratorios departamentales de salud publica del pais puedan cumplir con la determinacion de anticuerpos IgG anti-T. gondii como prueba diagnostica en el control prenatal, cuando no se cuente con la infraestructura necesaria para la tecnica de IFI, teniendo en cuenta que la de ELISA esta fundamentada en el grado de afinidad de anticuerpos por un antigeno determinado y no mide el nivel real de estos en una muestra de suero, como si lo hace la tecnica de IFI.

[Characterization of the national malaria diagnostic network, Colombia, 2006-2010].

INTRODUCTION The implementation and development of activities of the quality assurance system of malaria diagnosis, allows the adequate operation of the national diagnostic network, needed to strengthen prevention and control actions of this important public health problem. OBJECTIVE To characterize the malaria diagnosis network in Colombia between 2006 and 2010. MATERIALS AND METHODS A retrospective study was made by reviewing the annual reports of malaria diagnosis network activities that were sent by the Public Health Laboratories (PHL) between 2006 and 2010. The study included analysis of diagnostic coverage in population at risk and an evaluation of activities and training to the people responsible for malaria diagnosis. RESULTS Malaria diagnostic coverage has increased in Colombia, from 53% of municipalities covered in 2006 to 80% in 2010. The number of places that perform diagnosis increased by 31% with a significant increase, for the same period, of the number of microscopists (56%) and laboratories (30%), to 1,195 and 1,780 respectively, registered in 2010. During the period of study, the percentage of PHL that carried out at least 3 of the activities of the quality assurance system for the diagnostic network at local level was 67%. CONCLUSIONS It is necessary to continue strengthening the malaria diagnosis network to provide timely and adequate diagnosis in order to reduce the morbidity and mortality by malaria.

Seroprevalencia de la toxoplasmosis y factores relacionados con las enfermedades transmitidas por alimentos en trabajadores de plantas de beneficio animal en cinco ciudades capitales de Colombia, 2008

The National Institute of Health of Colombia, to determine the prevalence of toxoplasmosis in slaughterhouse workers, determined the antibodies against Toxoplasma gondii in the target population. The objective was to determine the seroprevalence of toxoplasmosis in workers in animal processing plants in five cities during 2008, by the ELFA technique (Enzyme Linked Fluorescent Assay). It conducted a cross sectional study in 400 workers randomly selected in animal processing plants operating in the clean area. In the 400 workers surveyed, it was found a seroprevalence of 71.8% (287) of IgG antibodies against Toxoplasma gondii and 2.8% (8) of IgM antibodies against Toxoplasma gondii , the latter residing in the cities of Bogota, BucaramangaMedellin (2 cases each), Monteria and Restrepo (one case each). The highest percentage of IgG positive for anti- Toxoplasma gondii was found in the cities of Restrepo and Villavicencio. The risks of exposure to toxoplasmosisresulted from not wearing full protective materials, food not properly washed, the consumption of undercookedmeat, exposure to animals, and ground handling.

Comparación entre metodologías para el diagnóstico microscópico de malaria

Introduction: As part of the pre-elimination plan for malaria in Colombia, it has been proposed to develop activities within the line of work: “Improve access and quality of malaria diagnosis”. Objective: To compare the methodology recommended by PAHO/WHO with that used in Colombia for the diagnosis of malaria. Materials and methods: Samples were collected and 88 slides were prepared for malaria diagnosis, under different scenarios according to the parameters to be evaluated. After duplicate mycroscopic reading, the respective variance calculations were performed for all possible staining comparisons with the two methods used (thick smear, combined thick smear), according to the staining (modified Romanowsky or Giemsa), with the result variable being the parasite density (500, 1,000, 5,000 and 10,000 parasites/μl of blood). Results: A Cohen kappa index of inter-rater agreement of 0.923 (95% CI: 0.768-1.078) was obtained. None of the factors (A: stain, B: methodology) or interactions (AB) had a statistically significant effect on the results with a 95% confidence level. Conclusion: Based on the results of the study, the preparation of two thick smears in the same slide stained with the modified Romanowsky stain is a suitable methodology for the diagnosis of malaria in Colombia, due to its technical characteristics, of storage, low cost, use and care.Introduction: As part of the pre-elimination plan for malaria in Colombia, it has been proposed to develop activities within the line of work: “Improve access and quality of malaria diagnosis”. Objective: To compare the methodology recommended by PAHO/WHO with that used in Colombia for the diagnosis of malaria. Materials and methods: Samples were collected and 88 slides were prepared for malaria diagnosis, under different scenarios according to the parameters to be evaluated. After duplicate mycroscopic reading, the respective variance calculations were performed for all possible staining comparisons with the two methods used (thick smear, combined thick smear), according to the staining (modified Romanowsky or Giemsa), with the result variable being the parasite density (500, 1,000, 5,000 and 10,000 parasites/μl of blood). Results: A Cohen kappa index of inter-rater agreement of 0.923 (95% CI: 0.768-1.078) was obtained. None of the factors (A: stain, B: methodology) or interactions (AB) had a statistically significant effect on the results with a 95% confidence level. Conclusion: Based on the results of the study, the preparation of two thick smears in the same slide stained with the modified Romanowsky stain is a suitable methodology for the diagnosis of malaria in Colombia, due to its technical characteristics, of storage, low cost, use and care.

Enfermedad de Chagas y su seroprevalencia en tres departamentos de la Amazonia colombiana

Objetivo. Determinar la seroprevalencia de la enfermedad de Chagas en poblacion general procedente de tres departamentos de la Amazonia colombiana: Vaupes, Amazonas y Guaviare y analizar variables de riesgo para la enfermedad. Metodos. Para determinar la seropositividad se analizaron 3429 muestras de suero obtenidas mediante previo consentimiento informado durante los anos 2009 y 2010 a traves de un muestreo probabilistico, de conglomerados, estratificado y trietapico para cada departamento, con probabilidades finales desiguales. Fueron analizadas en el Laboratorio de Parasitologia del Instituto Nacional de Salud de Bogota mediante dos tecnicas de diagnostico, Inmunoensayo enzimatico (Elisa) e Inmunofluorescencia indirecta (IFI) empleando como antigeno una cepa de Trypanosoma cruzi colombiana previamente caracterizada como linaje T cI. Resultados. Se encontro una seroprevalencia general de 0,99%, 2,07% para el departamento del Guaviare, 0,79% para el departamento de Vaupes y 0,09% para el departamento de Amazonas. Estos resultados permitiran establecer una linea de base epidemiologica que contribuya a las estrategias de control de la enfermedad en esta zona.