Alberto Tobón

Clinical and laboratory findings of Plasmodium vivax malaria in Colombia, 2001

A descriptive study was carried out in 104 patients with Plasmodium vivax malaria, from the region of Turbo (Antioquia, Colombia). Clinical features and levels of hemoglobin, glycemia, serum bilirubin, alanine-aminotransferase (ALT), aspartate-aminotransferase (AST), creatinine and complete blood cell profile were established. 65% of the studied individuals were men and their mean age was 23. Of all individuals 59% had lived in the region for > 1 year and 91% were resident in the rural area. 42% were farmers and 35% had a history of malaria. The mean parasitaemia was 5865 parasites/mm3. The evolution of the disease was short (average of 4.0 days). Fever, headache and chills were observed simultaneously in 91% of the cases while the most frequent signs were palmar pallor (46%), jaundice (15%), hepatomegaly (17%), and spleen enlargement (12%). Anemia was found in 39% of the women and in 51% of the men, 8% of individuals had thrombocytopaenia and 41% had hypoglycemia.

Therapeutic efficacy test in malaria falciparum in Antioquia, Colombia

ObjectiveEvaluate the frequency of failure of eight treatments for non-complicated malaria caused by Plasmodium falciparum in patients from Turbo (Urabá region), El Bagre and Zaragoza (Bajo Cauca region), applying the 1998 protocol of the World Health Organization (WHO). Monotherapies using chloroquine (CQ), amodiaquine (AQ), mefloquine (MQ) and sulphadoxine-pyrimethamine (SP), and combinations using chloroquine-sulphadoxine-pyrimethamine (CQ-SP), amodiaquine-sulphadoxine-pyrimethamine (AQ-SP), mefloquine-sulphadoxine-pyrimethamine (MQ-SP) and artesunate-sulphadoxine-pyrimethamine (AS-SP), were examined.MethodologyA balanced experimental design with eight groups. Samples were selected based on statistical and epidemiological criteria. Patients were followed for 21 to 28 days, including seven or eight parasitological and clinical evaluations, with an active search for defaulting patients. A non-blinded evaluation of the antimalarial treatment response (early failure, late failure, adequate response) was performed.ResultsInitially, the loss of patients to follow-up was higher than 40%, but the immediate active search for the cases and the monetary help for transportation expenses of patients, reduced the loss to 6%. The treatment failure was: CQ 82%, AQ 30%, MQ 4%, SP 24%, CQ-SP 17%, AQ-SP 2%, MQ-S-P 0%, AS-SP 3%.ConclusionThe characteristics of an optimal epidemiological monitoring system of antimalarial treatment response in Colombia are discussed. It is proposed to focus this on early failure detection, by applying a screening test every two to three years, based on a seven to 14-day follow-up. Clinical and parasitological assessment would be carried out by a general physician and a field microscopist from the local hospital, with active measures to search for defaulter patients at follow-up.

Malaria-related anaemia: a Latin American perspective

Malaria is the most important parasitic disease worldwide, responsible for an estimated 225 million clinical cases each year. It mainly affects children, pregnant women and non-immune adults who frequently die victims of cerebral manifestations and anaemia. Although the contribution of the American continent to the global malaria burden is only around 1.2 million clinical cases annually, there are 170 million inhabitants living at risk of malaria transmission in this region. On the African continent, where Plasmodium falciparum is the most prevalent human malaria parasite, anaemia is responsible for about half of the malaria-related deaths. Conversely, in Latin America (LA), malaria-related anaemia appears to be uncommon, though there is a limited knowledge about its real prevalence. This may be partially explained by several factors, including that the overall malaria burden in LA is significantly lower than that of Africa, that Plasmodium vivax, the predominant Plasmodium species in the region, appears to display a different clinical spectrus and most likely because better health services in LA prevent the development of severe malaria cases. With the aim of contributing to the understanding of the real importance of malaria-related anaemia in LA, we discuss here a revision of the available literature on the subject and the usefulness of experimental animal models, including New World monkeys, particularly for the study of the mechanisms involved in the pathogenesis of malaria.

Resistencia de Plasmodium falciparum a tres fármacos antimaláricos en Turbo (Antioquia, Colombia), 1998

En 1998, se determino in vivo e in vitro la frecuencia y el grado de resistencia de Plasmodium falciparum a los tres farmacos antimalaricos (cloroquina, amodiaquina y sulfadoxina/ pirimetamina) mas utilizados en el municipio de Turbo (zona de Uraba, Antioquia, Colombia) en una muestra representativa de la poblacion con malaria. Se realizaron analisis clinicos y parasitologicos durante 14 dias segun la prueba estandar recomendada por la Organizacion Mundial de la Salud. In vivo, P. falciparum mostro resistencia a la cloroquina, amodiaquina y sulfadoxina/pirimetamina con una frecuencia de 97, 7 y 13%, respectivamente; in vitro, las cifras correspondientes fueron de 21, 23 y 9%, respectivamente. La concordancia entre los resultados in vivo e in vitro fue de 23% para la cloroquina.

Congenital malaria in Urabá, Colombia.

BackgroundCongenital malaria has been considered a rare event; however, recent reports have shown frequencies ranging from 3% to 54.2% among newborns of mothers who had suffered malaria during pregnancy. There are only a few references concerning the epidemiological impact of this entity in Latin-America and Colombia.ObjectiveThe aim of the study was to measure the prevalence of congenital malaria in an endemic Colombian region and to determine some of its characteristics.MethodsA prospective, descriptive study was carried out in the mothers who suffered malaria during pregnancy and their newborns. Neonates were clinically evaluated at birth and screened for Plasmodium spp. infection by thick smear from the umbilical cord and peripheral blood, and followed-up weekly during the first 21 days of postnatal life through clinical examinations and thick smears.Results116 newborns were included in the study and 80 umbilical cord samples were obtained. Five cases of congenital infection were identified (four caused by P. vivax and one by P. falciparum), two in umbilical cord blood and three in newborn peripheral blood. One case was diagnosed at birth and the others during follow-up. Prevalence of congenital infection was 4.3%. One of the infected newborns was severely ill, while the others were asymptomatic and apparently healthy. The mothers of the newborns with congenital malaria had been diagnosed with malaria in the last trimester of pregnancy or during delivery, and also presented placental infection.ConclusionsCongenital malaria may be a frequent event in newborns of mothers who have suffered malaria during pregnancy in Colombia. An association was found between congenital malaria and the diagnosis of malaria in the mother during the last trimester of pregnancy or during delivery, and the presence of placental infection.

Pathogenic mechanisms in Plasmodium falciparum malaria

The most recognized pathogenic mechanisms of the infection with Plasmodium falciparum, during both the erythrocytic and exo-erythrocytic stages are presented. Vascular obstruction explained by the sequestration of parasitized red blood cells and erythrocyte rosetting, mediated by different endothelial ligands and receptors, in addition to the inflammatory processes induced by the presence of the parasite, are central aspects in the pathogenesis of malaria that explain the processes of damage, dysfunction and cell death in various organs. Alterations such as increased vascular permeability, hypoxia and anaerobic metabolism leading to localized lesions in organs such as brain and lung, as well as to a generalized acidotic state with multisystem failure can be explained by events such as the injury and destruction of erythrocytes, hepatocytes and endothelial cells, the loss of endothelial integrity, and the activation of cell damage and apoptosis promoters.

Ictericia y hepatopatía en el paciente con malaria

Resumen La ictericia es un hallazgo frecuente en el paciente con malaria. Segun la Organizacion Mundial de la Salud, se considera un signo de peligro cuando se acompana de aumento importante de las bilirrubinas y comunmente se relaciona con disfuncion hepatica y lesion de otros sistemas. La lesion hepatica en estos pacientes es frecuente, esta asociada a otras complicaciones, y es reversible si se identifica y se trata a tiempo. Con este trabajo se pretende revisar el valor semiologico de la ictericia como indicador de malaria complicada, explicar su patogenesis y los mecanismos de dano hepatico; ademas, hacer un enfoque del paciente con hepatopatia paludica, diferenciando la disfuncion hepatica de la falla y la encefalopatia hepaticas.

Diagnostic accuracy of loop-mediated isothermal amplification (LAMP) for screening malaria in peripheral and placental blood samples from pregnant women in Colombia

BackgroundPregnant women frequently show low-density Plasmodium infections that require more sensitive methods for accurate diagnosis and early treatment of malaria. This is particularly relevant in low-malaria transmission areas, where intermittent preventive treatment is not recommended. Molecular methods, such as polymerase chain reaction (PCR) are highly sensitive, but require sophisticated equipment and advanced training. Instead, loop mediated isothermal amplification (LAMP) provides an opportunity for molecular detection of malaria infections in remote endemic areas, outside a reference laboratory. The aim of the study is to evaluate the performance of LAMP for the screening of malaria in pregnant women in Colombia.MethodsThis is a nested prospective study that uses data and samples from a larger cross-sectional project conducted from May 2016 to January 2017 in three Colombian endemic areas (El Bagre, Quibdó, and Tumaco). A total of 531 peripheral and placental samples from pregnant women self-presenting at local hospitals for antenatal care visits, at delivery or seeking medical care for suspected malaria were collected. Samples were analysed for Plasmodium parasites by light microscopy (LM), rapid diagnostic test (RDT) and LAMP. Diagnostic accuracy endpoints (sensitivity, specificity, predictive values, and kappa scores) of LM, RDT and LAMP were compared with nested PCR (nPCR) as the reference standard.ResultsIn peripheral samples, LAMP showed an improved sensitivity (100.0%) when compared with LM 79.5% and RDT 76.9% (p < 0.01), particularly in afebrile women, for which LAMP sensitivity was two-times higher than LM and RDT. Overall agreement among LAMP and nPCR was high (kappa value = 1.0). Specificity was similar in all tests (100%). In placental blood, LAMP evidenced a four-fold improvement in sensitivity (88.9%) when compared with LM and RDT (22.2%), being the only method, together with nPCR, able to detect placental infections in peripheral blood.ConclusionsLAMP is a simple, rapid and accurate molecular tool for detecting gestational and placental malaria, being able to overcome the limited sensitivity of LM and RDT. These findings could guide maternal health programs in low-transmission settings to integrate LAMP in their surveillance systems for the active detection of low-density infections and asymptomatic malaria cases.