RESUMEN
Early and accurate diagnosis is critical in reducing the morbidity and mortality associated with malaria. Microscopy (MI) is the current diagnostic gold standard in the field; however, it requires expert personnel, is time-consuming, and has limited sensitivity. Although rapid diagnostic tests for antigen detection (RDTs) are an alternative to diagnosis, they also have limited sensitivity and produce false positive results in detecting recent past infection. The automated hematology analyzer XN-31 prototype (XN-31p) (Sysmex Corporation, Kobe, Japan) is able to identify plasmodium-infected erythrocytes, count parasitemia and perform complete blood-cell counts within one minute. The performance of the XN-31p in diagnosing malaria was evaluated and compared with real-time polymerase chain reaction (qPCR), MI and RDT in an endemic area of Colombia where Plasmodium falciparum and Plasmodium vivax are present. Acute febrile patients were enrolled from July 2018 to April 2019 in Quibdó, Colombia. Malaria diagnoses were obtained from MI and RDT in the field and later confirmed by qPCR. Venous blood samples in EDTA were processed with an XN-31p in the field. Sensitivity, specificity, positive/negative predictive values, and the likelihood ratios of positive and negative tests were calculated with respect to the results from qPCR, MI and RDT. The intraclass correlation coefficient (ICC) and Bland-Altman plot were used to evaluate the concordance in the parasitemia with respect to MI. A total of 1,754 subjects were enrolled. The mean age was 27.0 years (IQR 14-44); 89.6% were Afro-Colombians, 94.3% lived in urban areas and 0.91% were pregnant. With respect to qPCR, the XN-31p showed a sensitivity of 90% (95% CI 87.24-92.34) and a specificity of 99.83% (95% CI 99.38-99.98) in detecting Plasmodium spp.; both parameters were equivalent to those for MI and RDT. Using MI as the reference, the XN-31p showed a sensitivity of 98.09% (95% CI 96.51-99.08), a specificity of 99.83% (95% CI 99.4-99.98), an ICC of 0.85 (95% CI 0.83-0.87) and an average difference of - 3096 parasites/µL when compared with thick-smear MI and an ICC of 0.98 (95% CI 0.97-0.98) and an average difference of - 0.0013% when compared with thin-smear MI. The XN-31p offers a rapid and accurate alternative method for diagnosing malaria in clinical laboratories in areas where P. falciparum and P. vivax cocirculate.
RESUMEN
En Colombia poco se han estudiado las parasitosis intestinales en caninos, y los perros de la calle constituyen un grupo de elevado riesgo para la adquisición de enfermedades zoonóticas parasitarias. Por medio de un estudio descriptivo transversal realizado en 2014 se determinó la prevalencia de parasitosis intestinal en 68 caninos de ambos sexos de dos centros de bienestar animal de Medellín y el oriente antioqueño (Colombia) y sus factores asociados. El diagnóstico parasitológico se realizó por examen directo con solución salina al 0,8 % y lugol, y el método de flotación de Sheather. La prevalencia global de enteroparásitos fue 72,1 % (49), helmintos 58,8 % (40), protozoos 33,8 % (23) y poliparasitismo en el 45,6 % (31). Se identificaron 11 agentes parasitarios, de los cuales los más prevalentes fueron Uncinaria stenocephalia, con el 39,7 % (27); Ancylostoma caninum, con el 20,6 % (14); Trichuris vulpis, con el 16,2 % (11), y Toxocara spp., con el 11,8 % (8). Estos fueron estadísticamente mayores en el oriente antioqueño (valor p chi² < 0,05). Taenia spp. presentó una prevalencia de 4,4 % (3) y fue mayor en Medellín. No hubo asociación entre la prevalencia de cada taxón con el sexo ni la edad (valor p > 0,05). Se evidenció una alta prevalencia de parasitismo intestinal en caninos de Medellín y del oriente antioqueño, y gran diversidad en las prevalencias de los subgrupos estudiados. Esta información pone de manifiesto la necesidad de fomentar investigaciones tendientes a conocer la magnitud y los factores asociados en poblaciones específicas como base para la orientación de acciones en salud veterinaria y la salud pública, dado el potencial zoonótico de algunas parasitosis de caninos.
In Colombia, there are very few studies about intestinal parasitosis in dogs, and street dogs constitute a high-risk group for the acquisition of parasitic zoonotic diseases. Through a cross-sectional descriptive study carried out in 2014, the prevalence of intestinal parasitosis and its associated factors were determined in 68 dogs of both sexes from two animal welfare centers in Medellin and eastern Antioquia (Colombia). The parasitological diagnosis was made by direct examination with saline solution at 0.8% and iodine, and the Sheather flotation method. The overall prevalence of intestinal parasitosis was 72.1% (49), helminths 58.8% (40), protozoa 33.8% (23) and parasitism in 45.6% (31). 11 parasitic agents, of which the most prevalent were Uncinaria stenocephala with 39.7% (27), were identified; Ancylostoma caninum, with 20.6% (14); Trichuris vulpis, with 16.2% (11) and Toxocara spp., with 11.8% (8). These were statistically higher in eastern Antioquia (p value chi² < 0,05). Taenia spp. presented a prevalence of 4.4% (3) and it was higher in Medellin. There was no association between the prevalence of each taxon to sex or age (p value > 0.05). A high prevalence of intestinal parasitism in dogs from Medellin and eastern Antioquia was evidenced, as well as a great diversity in the prevalence of the subgroups studied. This information highlights the need to promote research in order to determine the magnitude and associated factors in specific populations as the foundation for targeting actions on veterinary health and public health, given the zoonotic potential of some parasitosis of dogs.
Na Colômbia são poucos os estudos realizados sobre as parasitoses intestinais em caninos, e os cachorros da rua constituem um grupo de elevado risco para a aquisição de doenças zoonótico parasitárias. Através de um estudo descritivo transversal realizado em 2014 se determinou a prevalência de parasitose intestinal em 68 caninos de ambos os sexos de dois centros de bem-estar animal de Medellín e do oriente da região de Antioquia (na Colômbia) e seus fatores associados. O diagnóstico parasitológico se realizou por exame direto com solução salina ao 0,8 % e lugol, e o método de flotação de Sheather. A prevalência global de enteroparasitas foi 72,1 % (49), helmintos 58,8 % (40), protozoários 33,8 % (23) e poli parasitismo em 45,6 % (31). Identificaram-se 11 agentes parasitários, dos quais os mais prevalentes foram Uncinaria stenocephala, com o 39,7 % (27); Ancylostoma caninum, com o 20,6 % (14); Trichuris vulpis, com 16,2 % (11), e Toxocara spp., com 11,8 % (8). Estes foram estatisticamente maiores no oriente da região de Antioquia (valor p chi² < 0,05). Taenia spp. Apresentou uma prevalência de 4,4 % (3) e foi maior em Medellín. Não houve associação entre a prevalência de cada táxon com o sexo nem a idade (valor p > 0,05). Evidenciou-se uma alta prevalência de parasitismo intestinal em caninos de Medellín e no oriente da região de Antioquia, e grande diversidade nas prevalências dos subgrupos estudados. Esta informação manifesta a necessidade de fomentar as pesquisas tendentes a conhecer a magnitude e os fatores associados em populações específicas como base para a orientação de ações em saúde veterinária e em saúde pública, devido o potencial zoonótico de algumas parasitoses de caninos.
