Evaluation of LAMP for the diagnosis of Loa loa infection in dried blood spots compared to PCR-based assays and microscopy

BACKGROUND Loa loa is a filarial species found exclusively in West and Central Africa. Microscopy is the traditional diagnosis method for human loiasis. Several molecular methods have developed as an alternative approach for identification of L. loa filarial parasites. OBJECTIVES The aim of this study was to evaluate a Loa-Loop-mediated isothermal amplification (LAMP) assay to diagnose loiasis disease on dried blood spots (DBS) samples, compared to microscopy, filaria-real time-polymerase chain reaction (PCR) and nested-Loa PCR. METHODS A total of 100 DBS samples and 100 blood smears were used for this study. DNA was extracted using saponin/Chelex method. DNA isolated was assayed by a Loa-LAMP assay in parallel to microscopy, filaria-real time PCR and nested-Loa PCR. The sensitivities and specificities of Loa-LAMP assay was computed comparing to each one of the reference methods. FINDINGS Loa-LAMP's sensitivity was more than 90% and specificity was nearly 100% when compared to molecular methods. On the other hand, sensitivity was decreased a bit when Loa-LAMP faced microscopy, but keeping the other statistical values high. MAIN CONCLUSIONS Loa-LAMP is an appropriate method for loiasis diagnosis in endemic areas. Though, it has disadvantages like the reagents' high price at the moment and not to be able to detect more filarial species at once.

Study of the prevalence of Plasmodium infections by the polymerase chain reaction (PCR) among patients with severe anaemia treated at a rural hospital in southern Ethiopia / Prevalencia de infección por Plasmodium mediante la reacción en cadena de la polimerasa (PCR) en pacientes con anemia grave atendidos en un hospital rural de sudeste de Etiopía

This study was conducted to determine the current burden of Plasmodium infections among patients with severe anaemia attending a rural hospital in southern Ethiopia. A total of 111 patients with severe anaemia (hemoglobin < 7 mg/dL) were included. The Plasmodium species causing the infection were identified using a Semi-nested Multiplex PCR. The mean age of the study population was 15 years and 26 (23.4%) individuals tested positive for malaria. Of these, 18 (16.2%) were infected by P. falciparum, 4 (3.6%) by P. vivax, and 4 by P. ovale. No significant associations between the species of Plasmodium and the sex of the patient or the haemoglobin values were found. This study showed that Plasmodium infections cause severe anaemia in one in four cases.

El estudio se ha llevado a cabo para conocer el impacto de la infección por especies de spp Plasmodium entre los pacientes con anemia grave atendidos en un hospital rural del sudeste de Etiopía. Se incluyeron en el estudio 111 pacientes con anemia grave (hemoglobina < 7 mg/dL). La infección por Plasmodium spp. se llevó a cabo mediante una PCR Semi-nested Multiplex. La media de edad de la población de estudio fue de 15 años; 26 pacientes presentaban infección por Plasmodium spp. (23.4%): 18 (16.2%) fueron para P. falciparum, 4 (3.6%) para P. vivax, and 4 (3.6%) para P. ovale. No encontramos asociación entre el tipo de Plasmodium con el sexo y el los valores de hemoglobina. Este estudio reveló la importancia que la infección por Plasmodium es responsable de la anemia grave en uno de cada cuatro pacientes evaluados.