Seroprevalencia y detección molecular de Toxoplasma gondii en donantes de un banco de sangre de Cúcuta, Colombia / Seroprevalence and molecular detection of Toxoplasma gondii among donors in a blood bank in Cúcuta, Colombia

Resumen Introducción. La infección por Toxoplasma gondii puede presentarse en los humanos con un amplio rango de manifestaciones que van desde el estado asintomático hasta la enfermedad grave, según el estado inmunológico del individuo. Los mecanismos de transmisión incluyen la transfusión sanguínea, pero poco se sabe sobre la frecuencia del parásito en los bancos de sangre de Colombia. Objetivo. Determinar la prevalencia de la infección con T. gondii en donantes de un banco de sangre de Cúcuta mediante técnicas de diagnóstico serológico y molecular. Materiales y métodos. Se determinaron los anticuerpos IgG e IgM contra T. gondii mediante un inmunoensayo en suero en 348 donantes. Se determinó la frecuencia de ADN de T. gondii utilizando la reacción en cadena de la polimerasa (PCR) en sangre total de donantes seropositivos y se analizaron las variables de interés con base en la información obtenida durante la selección de donantes. Resultados. De los 348 donantes participantes, 134 (38,5 %) presentaron anticuerpos IgG contra T. gondii; dos (0,6 %) de ellos presentaron tanto IgG como IgM y, en dos (1,5 %), se detectó ADN del parásito en la sangre. Un análisis bivariado evidenció una asociación entre la seropositividad para T. gondii y tener más de 26 años de edad (p=0,020). Conclusiones. La prevalencia de la infección con T. gondii encontrada en los donantes de sangre sugiere una exposición significativa al agente, la cual adquiere relevancia al detectarse la parasitemia.

Abstract Introduction: Toxoplasma gondii infection manifests differently in humans according to their immunity ranging from asymptomatic profiles to severe disease. There are multiple transmission mechanisms including blood transfusions, but little is known about the frequency of T. gondii infection in Colombia's blood banks. Objective: To determine the prevalence of T. gondii infection in blood donors of a blood bank in the city of Cúcuta by serological and molecular diagnostic techniques. Materials and methods: We identified IgG and IgM antibodies against T. gondii by immunoassay in serum from 348 donors. The frequency of T. gondii DNA was determined by polymerase chain reaction (PCR) in whole blood from seropositive donors and relevant variables were analyzed based on the information obtained from surveys during blood donor selection. Results: Out of the 348 enrolled donors, 134 (38.5%) showed IgG antibodies against T. gondii; two of them (0.6%) had both IgG and IgM, and in two of them (1.5%), parasite DNA was detected in blood samples. A bivariate analysis indicated an association between seropositivity to T. gondii and being over 26 years of age (p=0.020). Conclusions: The prevalence of T. gondii infection found in the blood donors of this study suggests a significant exposure to the infectious agent that becomes relevant when parasitemia is detected.

Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.

Variation in haematological parameters in children less than five years of age with asymptomatic Plasmodium infection: implication for malaria field studies

During the season of high malaria transmission, most children are infected by Plasmodium, which targets red blood cells (RBCs), affecting haematological parameters. To describe these variations, we examined the haematological profiles of two groups of children living in a malaria-endemic area. A cross-sectional survey was conducted at the peak of the malaria transmission season in a rural area of Burkina Faso. After informed consent and clinical examination, blood samples were obtained from the participants for malaria diagnosis and a full blood count. Of the 414 children included in the analysis, 192 were not infected with Plasmodium, whereas 222 were asymptomatic carriers of Plasmodium infection. The mean age of the infected children was 41.8 months (range of 26.4-57.2) compared to 38.8 months (range of 22.4-55.2) for the control group (p = 0.06). The asymptomatic infected children tended to have a significantly lower mean haemoglobin level (10.8 g/dL vs. 10.4 g/dL; p < 0.001), mean lymphocyte count (4592/µL vs. 5141/µL; p = 0.004), mean platelet count (266 x 103/µL vs. 385 x 103/µL; p < 0.001) and mean RBC count (4.388 x 106/µL vs. 4.158 x 106/µL; p < 0.001) and a higher mean monocyte count (1403/µL vs. 1192/µL; p < 0.001) compared to the control group. Special attention should be applied when interpreting haematological parameters and evaluating immune responses in asymptomatic infected children living in malaria-endemic areas and enrolled in vaccine trials.

Respuesta terapéutica de Plasmodium vivax a la cloroquina, en Riberalta, Guayaramerín y Yacuiba, Bolivia / Therapeutic response of Plasmodium vivax to chloroquine in Bolivia

Introducción. La determinación de la eficacia de la cloroquina contra Plasmodium vivax permite mejorar la capacidad de vigilancia de la resistencia a los antipalúdicos. Objetivo. Evaluar la eficacia terapéutica de la cloroquina como tratamiento de malaria no complicadapor P. vivax en Riberalta, Guayaramerín y Yacuiba, Bolivia. Materiales y métodos. Se llevó a cabo un estudio de la eficacia in vivo en pacientes mayores de cinco años; se suministró cloroquina (25 mg/kg en tres días) y se hizo seguimiento por 28 días, midiendo los niveles de cloroquina en sangre y desetilcloroquina, el día dos y el día de registro de reaparición de parasitemia. Para la evaluación de la incidencia acumulada de falla del tratamiento, se usó el análisis de supervivencia de Kaplan-Meier. Resultados. Se estudiaron 223 pacientes (Riberalta, 84; Guayaramerín, 80; Yacuiba, 59). Las medias de densidad parasitaria (formas asexuadas) del día 0 en Riberalta fueron de 6.147, en Guayaramerín, 4.251, y en Yacuiba, 5.214 parásitos/μl de sangre. En el mismo orden, los promedios de concentraciones sanguíneas de cloroquina-desetilcloroquina del día 2 fueron de 783, 817 y 815 ng/ml. Mientras en Yacuiba no se presentaron fracasos terapéuticos, en Riberalta ocurrieron con frecuencia de 6,2 % y en Guayaramerín de 10 %. Los valores de cloroquina y desetilcloroquina en sangre de pacientes con fracaso terapéutico fueron menores de 70 ng/ml en el día de reaparición de parasitemia. Conclusión. No se evidenció resistencia de P. vivax a la cloroquina en las tres regiones de evaluación en Bolivia. Se requieren mayores estudios de la concentración de la cloroquina en sangre.

Introduction. Knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance. Objective. The therapeutic efficacy of chloroquine as treatment was evaluated for uncomplicated Plasmodium vivax malaria in Bolivia. Materials and methods. An in vivo efficacy study of chloroquine was undertaken in three regions of Bolivia--Riberalta, Guayaramerín and Yacuiba. Two hundred and twenty-three patients (84, 80, and 59 in the three regions, respectively) aged over 5 years old were administered with chloroquine (25 mg/kg/three days) and followed for 28 days. Blood levels of chloroquine and desethylchloroquine were measured on day 2 and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan and Meier survival analysis. Results. The mean parasitemias (asexual) on day 0 were 6,147 parasites/μl of blood in the Riberalta population, 4,251 in Guayaramerín and 5,214 in Yacuiba. The average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817, and 815 ng/ml, respectively. No treatment failures were observed in Yacuiba, whereas in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia. Conclusion. Resistance of Plasmodium vivax to chloroquine was not demonstrated in three regions of Bolivia.

Caracterización de la transmisión de la malaria por Plasmodium vivax en la región fronteriza de Panamá con Costa Rica en el municipio de Barú, Panamá / Characterization of Plasmodium vivax malaria transmission at the border of Panamá and Costa Rica

Introducción. Pocos estudios describen los factores asociados con la dinámica de transmisión de la malaria, o paludismo, por Plasmodium vivax en las regiones endémicas de Panamá. Objetivo. Caracterizar la dinámica de transmisión de la malaria producida por P. vivax en la región fronteriza de Panamá con Costa Rica. Materiales y métodos. Se llevó a cabo un estudio observacional, descriptivo y transversal. Se evaluaron la incidencia parasitaria anual, el índice de láminas positivas y el índice anual de exámenes de sangre. Se identificaron los anofelinos vectores, y se caracterizaron sus criaderos preferenciales, densidad larvaria e índice de picada/hombre/noche. Se hizo búsqueda pasiva y activa de casos sospechosos mediante examen de gota gruesa. Resultados. De 10.401 muestras de gota gruesa, 83 resultaron positivas para P. vivax. El 84 % de los casos provenía de zonas rurales, el 79 % constituía una población económicamente activa, la mediana de edad fue de 36 años y, la media, de 30 años. El 58,5 % de los casos fueron de sexo masculino. La incidencia parasitaria anual fue de 4,1 por 1.000 habitantes; el índice de láminas positivas fue de 0,8 % y el índice anual de exámenes de sangre fue de 51,9 %. El 65,0 % de los casos diagnosticados registró entre 100 y 2.000 parásitos/μl de sangre. Se identificaron los mosquitos vectores Anopheles albimanus y An. punctimacula. Conclusión. Es necesario el seguimiento de estudios entomológicos, el fortalecimiento de la vigilancia epidemiológica, la consideración de los factores de riesgo y la realización de un trabajo en coordinación con las autoridades de salud de Costa Rica, para controlar la malaria en esta región.

Introduction. Few studies have described the factors associated with Plasmodium vivax transmission dynamics in endemic regions from Panamá. Objective. Malaria transmission dynamics produced by P. vivax were characterized at the border between Panamá and Costa Rica. Materials and methods. In the municipality of Barú, an observational, descriptive and cross-sectional study was undertaken to measure the annual parasite index (API), slide positivity index (SPR), and the annual blood examination rate (ABER). The most frequent symptoms and signs in malaria patients were recorded. The anopheline species were identified in the area and the preferred larval habitats, the density of larval populations in the larval habitats and the bites/human/night were characterized. Results. Of a total of 10,401 thick smear blood samples, 83 were positive for P. vivax. Of these, 84% came from rural areas and 79% were from economically active individuals. The median and average ages were 36 and 30 years, respectively, and 58.5% of the malaria cases were male. API was 4.1/1,000 inhabitants; SPR was 0.8% and ABER was 51.9%. Of the diagnosed cases, 54% showed blood parasitemias ranging between 100-2,000 parasites/μl. The majority of the cases were observed in May and June. Two mosquito vector species were identified-- Anopheles albimanus and An. punctimacula. Conclusion. These observations indicate the advisibility of continued entomological studies, strengthening of epidemiological surveillance, consideration of additional risk factors and evaluation of work performance in the border region. This will require coordination with health authorities of both countries to control malaria in this region.

Seroepidemiología del paludismo en un grupo de migrantes en tránsito (Chiapas, 2008)

OBJETIVO: Conocer la prevalencia del paludismo y los factores asociados con la infección de migrantes en la frontera sur de México, durante 2008. MATERIAL Y MÉTODOS: En 706 migrantes, se investigó la infección activa mediante prueba rápida y PCR o pasada, mediante serología y se aplicó un cuestionario para investigar las condiciones asociadas con la infección. RESULTADOS: 85.6% provenía de Centroamérica. Ninguno presentó infección activa; 4.2% fue seropositivo y la mayoría provenía de los países con mayor incidencia de paludismo en la región. La seropositividad se asoció con el número de episodios previos de paludismo (RM=1.44; IC95% 1.04-2.00), años de permanencia en su comunidad de origen (RM=1.03; IC95% 1.00 -1.07) y conocimiento y automedicación con antipalúdicos (RM=3.38; IC95% 1.48-7.67). CONCLUSIONES: La exposición previa de migrantes al paludismo y las dificultades para su detección indican la necesidad de nuevas estrategias para la vigilancia epidemiológica para estas poblaciones.

OBJECTIVE: To know the prevalence of malaria and the factors associated with the infection in migrants in the southern border of Mexico, during 2008. MATERIALS AND METHODS: In 706 migrants, active malaria infection was investigated using a rapid diagnostic test and PCR and past infection using serology. A questionnaire was applied to investigate the conditions associated to infection. RESULTS: 85.6% originated from Central America, none presented an active infection, although 4.2% were seropositive, most of these came from the countries with the highest malaria incidence in the region. Seropositivity was associated with the number of previous malaria episodes (OR=1.44; IC95% 1.04-2.00), years living in their community of origin (OR=1.03; IC95% 1.00-1.07), and knowledge and self-medication with anti-malaria drugs (OR=3.38; IC95% 1.48-7.67). CONCLUSIONS:. The previous exposure of migrants and the difficulties for their detection indicate the need of new strategies for the epidemiological surveillance for these populations.

Aporte de la técnica de PCR en el diagnóstico de Mansonella ozzardi en zonas endémicas de la Argentina / Contribution of the PCR assay to the diagnosis of Mansonella ozzardi in endemic areas of Argentina

Mansonella ozzardi es un nematode parásito tisular, agente etiológico de mansonellosis en casi la totalidad de los países latinoamericanos. En Argentina la mansonellosis ha sido descrita a lo largo de la región de las yungas. Su diagnóstico microscópico puede dar resultados falsos negativos en microfilaremias bajas. El objetivo del presente estudio fue optimizar su diagnóstico molecular y comparar los resultados con los obtenidos mediante las pruebas microscópicas de Knott, de gota gruesa y de extendido hemático fino, en 92 muestras de sangre de pacientes de zona endémica. La técnica de PCR seguida de la secuenciación del producto amplificado presentó una sensibilidad del 100 % frente al método de Knott, considerado como referencia, e incluso permitió identificar 7 casos más de la parasitosis.

Mansonella ozzardi is a tissue-dwelling parasitic nematode, the causative agent of mansonelliasis in almost all Latin American countries. It has been described along the Argentine Yungas region. The microscopic diagnosis can yield false-negative test results at low microfilaremia levels. The aim of this study was to optimize the molecular diagnostic technique and compare it with the Knott's method and standard blood smear procedures (thin blood films and thick smears) in 92 blood samples of individuals from an endemic area. The PCR technique followed by the sequencing of the amplified product yielded 100 % sensitivity compared to the Knott's test, which is considered a reference method. Seven more cases of this parasitosis could only be identified with the molecular technique.

Blood parasites in passerine birds from the Brazilian Atlantic Forest / Hemoparasitos em passeriformes da Mata Atlântica Brasileira

Parasites may lead bird species to extinction, affect host temporal and spatial population dynamics, alter community structure and alter individuals’ social status. We evaluated blood parasite prevalence and intensity according to bird families and species, among 925 birds that were caught in 2000 and 2001, in the Atlantic Forest in the State of Minas Gerais, Brazil. We applied Giemsa staining to thin blood smears, to detect blood parasites. The birds (n = 15.8%) in 11 families, were infected by at least one parasite genus, especially Muscicapidae (28.3%) and Conopophagidae (25%). Among the 146 infected birds, Plasmodium was detected in all bird families and had the highest prevalence (54.8%). Trypanosoma, Haemoproteus and microfilaria had lower prevalence rates (23.3, 23.3 and 2.1%, respectively). Birds caught during the rainy season were more infected than birds caught during the dry season. The overall low prevalence of blood parasites in birds is similar to the patterns found elsewhere in the Neotropical region.

Parasitos podem levar espécies de aves à extinção, afetar as dinâmicas temporais e espaciais dos hospedeiros, alterar a estrutura de comunidades e o status social de indivíduos. Avaliou-se a prevalência e a intensidade de parasitos em famílias e espécies de 925 aves capturadas, entre 2000 e 2001, na Mata Atlântica de Minas Gerais. Foram coradas com Giemsa extensões de sangue para detectar parasitos hematozoários. As aves (n= 15,8%) 11 famílias estavam infectadas por pelo menos um gênero de parasito, especialmente Muscicapidae (28,3%) e Conopophagidae (25%). Entre as 146 aves infectadas, Plasmodium foi detectado em todas as famílias e possuiu a maior prevalência (54,8%). Trypanosoma,Haemoproteus e microfilaria possuíram baixas prevalências (23,3, 23,3 e 2,1%, respectivamente). Aves capturadasdurante a estação chuvosa estavam mais infectadas do que aves capturadas durante a estação seca. A baixa prevalência geral de parasitos do sangue das aves é semelhante aos padrões encontrados em outras localidades da região Neotropical.

Enteroparasitosis prevalence and parasitism influence in clinical outcomes of tuberculosis patients with or without HIV co-infection in a reference hospital in Rio de Janeiro (2000-2006)

Tuberculosis and intestinal parasites affect primarily low social and economic level populations, living clustered in precarious habitational settings. One of the interesting aspects of this interaction is the parasitism influence in cellular response to tuberculosis. In the present study, we evaluated the prevalence of enteroparasitosis in tuberculosis patients, HIV-infected and non HIV infected, and we observed the influence of helminth presence in the response to tuberculin skin test (TST) and tuberculosis clinical outcomes. From 607 clinical records reviewed, 327 individuals met the study inclusion criteria and did not present any exclusion criteria. The prevalence of enteroparasites observed was 19.6 percent. There was no significant association among TST result and the variables related to the presence of: helminthes, protozoa, and stool test for parasites result (p>0.5). Considering the survival of this cohort, we may observe that there is no significant difference (p>0.05) between the survival curves of parasited and non parasited individuals. Solely the variable "eosinophils" presents a statistically significant association (p<0.001) with helminthes, all other associations are considered not significant. Our findings neither show an association between helminthic infection and a favorable tuberculosis outcome, nor between parasitism and TST response, unlike other in vitro studies. Apparently, experimental data do not correspond to the clinical findings.

Malaria prevention practices among mothers delivering in an urban hospital in southwest Nigeria.

BACKGROUND & OBJECTIVES: The pregnant woman is more prone to malaria than her non-pregnant counterpart with grave consequences for both mother and baby. This study aims at determining the malaria prevention practices among pregnant women in an area hyper-endemic for malaria. METHODS: For the study 983 parturient mothers were enrolled in Ibadan, southwest Nigeria. Information was collected on sociodemographic characteristics, use of malaria chemoprophylaxis, use of anti-vector measures, and malaria parasitaemia. RESULTS: Most mothers [956/972 (98.4%)] reported the use of anti-vector measures for malaria prevention. These include, window screens (78.9%), insecticides spray (69.9%), mosquito coils (25.3%), untreated bednets (2.5%), and insecticide-treated nets (1.1%). Most mothers used anti-vector measures either singly or in combination. About 86% (840/972) of the mothers used drugs for chemoprophylaxis. Thirteen (1.3%) mothers used chemoprophylaxis alone (CP), 135 (13.9%) used anti-vector measures alone (AV) while 820 (84.4%) used chemoprophylaxis plus anti-vector (CPAV). Weekly dose of pyrimethamine [214 (25%)] and intermittent preventive treatment with sulphadoxine-pyrimethamine [598 (71.2%)] were the widely used chemoprophylactic drugs. The prevalence of patent parasitaemia at delivery was 7.7% (1/13), 12.1% (99/820) and 16.3% (22/135) among CP, CPAV and AV groups respectively. Geometric mean parasite densities among the respective groups were 7840/microl, 1228/microl and 8936/microl. CONCLUSION: Window screens and insecticide sprays were widely used for malaria prevention while the use of ITN was very low among enrolled mothers. There is a need to pay concerted efforts to improve ITN usage rate in Nigeria.

Epidemiologia da doença de Chagas em quatro localidades rurais de Jaguaruana, Estado do Ceará: soroprevalência da infecção, parasitemia e aspectos clínicos / Epidemiology of Chagas disease in four rural localities in Jaguaruana, State of Ceará: seroprevalence of infection, parasitemia and clinical characteristics

Um estudo transversal sobre a doença de Chagas realizado com o exame da população de quatro localidades (nº= 541 habitantes) do município de Jaguaruana, estado do Ceará, mostrou: a soroprevalência da infecção chagásica em 3,1 por cento, avaliada pelos testes de imunofluorescência indireta, hemaglutinação indireta e ELISA, maior entre as pessoas com mais de 50 anos e sem diferença em relação ao sexo; a parasitemia positiva em 11,8 por cento (2/17) soropositivos, determinada pelo xenodiagnóstico indireto e em 75 por cento (9/12) pela reação em cadeia da polimerase (p<0,05); a cardiopatia em 41 por cento (7/17) dos soropositivos e em 11,8 por cento (2/17) dos controles soronegativos (p< 0,05), avaliada por anamnese, exame físico e eletrocardiograma de repouso. A análise desses resultados mostrou que as prevalências da parasitemia positiva e da cardiopatia chagásica crônica são semelhantes às da Caatinga do Piauí e maiores do que no Sertão da Paraíba, apesar de historicamente, todas essas áreas apresentarem o Triatoma brasiliensis e o Triatoma pseudomaculata como principais responsáveis pela transmissão da infecção chagásica.

A cross-sectional study on Chagas disease that examined the populations of four localities (nº = 541 inhabitants) in the municipality of Jaguaruana, State of Ceará, showed seroprevalence of Chagas infection of 3.1 percent, as assessed by indirect immunofluorescence, indirect hemagglutination and ELISA tests. The rate was higher among adults over 50 years old, without any difference in relation to sex. Positive parasitemia was found in 11.8 percent (2/17) of the seropositive individuals by means of indirect xenodiagnosis and in 75 percent (9/12) by means of the polymerase chain reaction (p < 0.05). Cardiopathy was found by means of anamnesis, physical examination and resting electrocardiogram in 41 percent (7/17) of the seropositive individuals and in 11.8 percent (2/17) of the seronegative controls (p < 0.05). Analysis of these results showed that the prevalences of positive parasitemia and chronic Chagas cardiopathy were similar to those in the Caatinga area of Piauí and greater than in the Sertão area of Paraíba, although all these areas historically presented Triatoma brasiliensis and Triatoma pseudomaculata as the primary vectors responsible for Chagas infection transmission.

Malaria situation in forest-fringed villages of Sonitpur district (Assam), India bordering Arunachal Pradesh during an outbreak.

BACKGROUND & OBJECTIVES: Epidemiological and entomological studies were undertaken in forest-fringed villages in Sonitpur district (Assam) bordering Arunachal Pradesh, India to assess the malaria situation. Blood smears (thick and thin) were collected from the fever cases through door-to-door survey. Both the blood smears stained with Giemsa were used for malaria parasite detection. Slide positivity rate (SPR) was recorded as 39.1% with predominance of Plasmodium falciparum (97.1%) infections. Children between 5 and 14 yr showed higher rates of infection. METHODS & RESULTS: Over all malaria prevalence was higher among the males (SPR 43.2%) than in females (SPR 34.5%). Adult mosquito collection was made using CDC miniature light-traps from dusk-to-dawn. Per-trap night density of mosquitoes in human dwellings and cattlesheds were 289 and 925, respectively. Anopheles minimus and An. dirus, the major vectors of malaria in Northeastern region of India formed 33.2% of the total vectors recorded. An. dirus could be recorded only from human dwellings. The results showed high malaria risk in the study villages. INTERPRETATION & CONCLUSION: High vector density with high parity rate, poor socio-economic conditions, lack of awareness, poor sanitation and congenial atmosphere for mosquito proliferation are aggravating the malaria situation in the study area.

Asymptomatic malaria parasitaemia in sickle-cell disease patients: how effective is chemoprophylaxis?

BACKGROUND & OBJECTIVES: Sickle-cell trait confers protection against malaria while homozygote sickle-cell disease (SCD) patients are at greater risk of malaria infection, hence the use of malaria chemoprophylaxis in SCD patients. The use of malaria chemoprophylaxis and asymptomatic parasitaemia were studied in SCD and non-SCD patients. STUDY DESIGN: A semi-structured questionnaire was administered to both patients and controls; a thick blood film was also examined in both the groups. RESULTS: Sixty-nine percent of patients use proguanil, 22% do not use any form of chemoprophylaxis, while 9% use pyrimethamine. There was no significant difference between level of parasitaemia in patients and controls (p = 0.1), a positive smear was found in equal numbers of patients on chemoprophylaxis and those not on chemoprophylaxis (p = 0.3). In the month preceding the study, 31% of patients vs 18% of controls had received treatment for malaria. There were no significant differences between patients and controls in frequency of malaria attacks (p = 0.06), last episode of malaria (p = 0.2). Ten percent of patients and 2% of controls use bednets. CONCLUSION: This study did not find any advantage in the use of malaria chemoprophylaxis in SCD patients over controls or SCD patients not on chemoprophylaxis. Vector control should also be considered in the fight against malaria. There is a need to look into why both patients and controls fail to use bednets in a malaria endemic country.

The prevalence of malaria parasitaemia in blood donors in a Nigerian teaching hospital.

BACKGROUND & OBJECTIVES: The present study was undertaken to assess the prevalence of malaria parasitaemia among blood donors and to determine the possible risk of transmission of malaria parasite to recipients of blood in Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State. METHODS: Four hundred and forty-four subjects were selected randomly and EDTA added blood was collected for screening malaria parasites using Giemsa stain. The data were subjected to chi2 analysis. RESULTS: Prevalence of malaria was 30.2% among blood donors and showed bimodal distribution with significant variation in different months. INTERPRETATION & CONCLUSION: Due to high prevalence of asymptomatic malaria parasitaemia in this region, all blood samples should be screened for malaria parasites (post-donor screening) and administered with a curative dose of antimalarials prophylactically to all patients transfused with malaria parasite positive blood.

Ausencia de malaria asintomática en escolares de Quibdó, Chocó / Absence of asymptomatic malaria in schoolchildren of Quibdó, Chocó

La malaria asintomática es considerada común en zonas de alta transmisión en África y prácticamente ausente en zonas de baja transmisión en Latinoamérica. Sin embargo, algunos reportes sugieren que el hallazgo de casos asintomáticos en zonas de alta y moderada transmisión en Latinoamérica es relativamente frecuente. La malaria asintomática tiene consecuencias graves no sólo para el individuo portador de parásitos, sino también para la comunidad donde vive. Los individuos crónicamente infectados se constituyen en un reservorio de la enfermedad que es difícil de identificar por medio de la vigilancia rutinaria de los programas de control. En el marco de un estudio de la epidemiología de la malaria en Quibdó, Chocó, se estimó la prevalencia de malaria asintomática en escolares. El objetivo fue establecer si los individuos con infección asintomática podrían constituir un reservorio importante de infección, capaz de mantener la transmisión local en esta ciudad. Se seleccionaron 255 estudiantes de cinco escuelas de Quibdó, de los cuales, 223 se incluyeron en el análisis. Algunos niños refirieron cefalea (34%), tos (32%) y diarrea (9%). Todos los resultados de gota gruesa fueron negativos. Además, el análisis por inmunofluorescencia indirecta de anticuerpos contra Plasmodium en una submuestra de 25 niños fue negativo. La prevalencia estimada de malaria asintomática en los escolares de Quibdó es, entonces, de 0% (IC95%: 0-1,4). La presencia de malaria asintomática en adultos no se puede descartar aunque es probable que, si existe, sea en una proporción muy baja.

Asymptomatic malaria is characteristic of high intensity transmission areas in Africa but unusual in low transmission areas in Latin America. Nevertheless, asymptomatic malaria has been reported to be frequent in areas in Latin America with high and moderate intensity of transmission. Asymptomatic malaria can affect both individuals who carry parasites and are cryptic carrier reservoirs for the community. Individuals chronically infected with malaria parasites are usually unidentifiable by most malaria control programmes. In order to identify whether asymptomatic individuals harboring malaria parasites are an important reservoir of infection in Quibdó, Chocó, the prevalence of asymptomatic malaria was assessed in schoolchildren. This study was part of a major study of the epidemiology of malaria in Quibdó. A total of 255 children from 5 schools were examined, of which 223 were included in the analysis. Children reported headache (34%), cough (32%), and diarrhoea (9%). None of the children presented a positive thick smear. In addition, IFA tests in a subsample of 25 children were negative. By these criteria, the prevalence of asymptomatic malaria in Quibdó schoolchildren is 0% (95%C.I.: 0.0-1.4). Although asymptomatic malaria in adults possibly occurs, a very low prevalence is predicted.

Epidemiological and entomological aspects of malaria in forest-fringed villages of Sonitpur district, Assam.

BACKGROUND & OBJECTIVES: Detailed epidemiological and entomological studies were undertaken in forest-fringed villages and a Tea Estate in Sonitpur, Assam to assess the malaria situation. METHODS: Door-to-door active surveillance was carried out to collect blood samples. Thick and thin blood smears stained with Giemsa were used for malaria parasite detection. Mosquito collections were made using CDC miniature light-traps and hand catch methods from dusk-to-dawn. RESULTS: 48% SPR, 49.1 Pf% was recorded from the study villages. Children between 10 and 14 years were most sufferers. Per trap night density of mosquitoes in human dwellings was 204.3 and in cattlesheds--908.7, An. minimus accounted for 20.7% of total malaria vectors. INTERPRETATION & CONCLUSION: The results showed high malaria risk in the study villages. High vector density with high parity rate, poor socio-economic conditions, lack of awareness, poor sanitation and congenial atmosphere for mosquito proliferation are aggravating the malaria situation more complex in the study area.

Mercury exposure and malaria prevalence among gold miners in Pará, Brazil

Economic development, including resource extraction, can cause toxic exposures that interact with endemic infectious diseases. Mercury is an immunotoxic metal used in the amalgamation of gold, resulting in both occupational exposures and environmental pollution. A cross-sectional medical survey was conducted in 1997 on 135 garimpeiros in Para, Brazil, because of their risks of both mercury exposure and malaria transmission. Mean levels of blood and urine mercury were well above non-exposed background levels. Twenty-six subjects had malaria parasitemia: Health symptoms consistent with mercury exposure were reported, but neither symptoms nor signs correlated with mercury levels in blood or urine. We did not find a dose response relationship between mercury exposure and likelihood of prevalent malaria infection, but there was a possible reduction in acquisition of immunity that may be associated with conditions in gold mining, including mercury exposure

Asymptomatic malarial parasitaemia in Tamil Nadu.

AIM: The aim of the study was to determine the community prevalence of asymptomatic malarial parasitaemia in the state of Tamil Nadu. METHODS: Free medical camps were organised in three randomly selected districts of Tamil Nadu, namely Dindigul, Ramnad and Thanjavur districts in November, 1997. Proportionate to population size cluster survey method was followed to collect peripheral blood smear by finger prick from 30 clusters in each district. Fifteen households were randomly selected from each district with the target age group of 15-45 years. Peripheral blood smears were stained by Leishman's stain and the slides were examined end to end by two independent experts to diagnose malarial parasites. RESULTS: The male:female ratio of the population studied was 1:1.6. Asymptomatic malaria was identified in 17 out of 569 individuals screened with a positive rate of 2.9% (CI 1.5-4.3). Out of the 17 malarial positive peripheral smears 15 were P. vivax and only two were P. falciparum with the predominance of gametocyte stage. CONCLUSION: This study reaffirms the prevalence of asymptomatic malaria in Tamil Nadu especially with P. vivax.

La malaria en el Amazonas: conocimientos, prácticas, prevalencia de parasitemia y evaluación entomológica en mayo de 1997 / Malaria in the Amazon region: knowledge, practices, prevalence of parasitaemia and entomological evaluation in May, 1997

Se realizó un estudio epidemiológico de malaria en el departamento del Amazonas que incluía la medición de los conocimientos y prácticas sobre malaria que tenían los pobladores de Arica en el río Putumayo, la prevalencia de parasitemia en una muestra de personas que viven en el área y el análisis de los datos de la vigilancia epidemiológica del departamento durante 1996. En el estudio de grupos focales en Arica, se encontró que las personas identifican a la malaria como una enfermedad transmitida por un mosquito, pero también, hay una proporción de personas que piensan que es transmitida por beber agua contaminada. La prevalencia de parasitemia en 37 muestras tomadas de personas que habían tenido enfermedad febril recientemente fue de 8 por ciento. Las personas que trabajaban en cultivos de coca tenían la mayor parasitemia (27 por ciento), mientras que ninguno de los que se dedicaban a esta actividad era positivo, p<0,01. En el grupo focal, la mayoría estuvo de acuerdo en que la enfermedad era producida por un mosquito, pero, en la encuesta, una proporción apreciable de personas dio respuesta equivocadas. Como posible vector de malaria en el área, solamente se encontró Anopheles oswaldoi, mientras que no se identificó Anopheles darlingi. Se notificaron 307 casos de malaria en el departamento durante 1996, de los cuales 72 fueron causados por Plasmodium falciparum (24 por ciento) y el resto por P. vivax. De 10 localidades analizadas, solamente en una predominaba P. falciparum (La Chorrera)., mientras que la localidad de Tarapacá reportó casos todo el año. El estudio muestra que la mayor parte del departamento del Amazonas es de transmisión inestable para malaria, pero hay por lo menos una localidad donde la transmisión es permanente, Tarapacá. También, se logró identificar a los trabajadores de cultivos ilícitos como una población de alto riesgo para el mantenimiento de la circulación del parásito en estas poblaciones