Desafíos y consideraciones bioéticas de la investigación para la salud en colaboración entre países del Norte y del Sur / Bioethical challenges and considerations of research for health in collaboration amongst Southern and Northern Countries / Desafios e considerações bioéticas da pesquisa em saúde em colaboração entre países do Norte e do Sul

Resumen: La investigación para la salud es esencial para enfrentar los retos actuales y futuros mediante la generación de nuevos conocimientos, que a su vez deben ser traducidos en mejores formas de prevenir y tratar las enfermedades, todo con el fin de lograr un desarrollo humano global sostenible. La tan necesaria investigación colaborativa Norte-Sur para la salud ha ido en franco aumento en las últimas décadas como respuesta a lo anterior. Por diversas razones, en esta interacción han surgido desafíos y cuestionamientos bioéticos que deben ser afrontados. En el presente trabajo se identifican 1) la asimetría; 2) el colonialismo; 3) la explotación; 4) la información, y 5) los comités de ética en investigación como los principales desafíos y se revisan los aspectos bioéticos que son necesarios atender. Resulta evidente la urgencia de construir una bioética de la investigación para la salud en colaboración entre países del Norte y países del Sur.

Abstract: Health research is essential to face current and future challenges by generating new knowledge, which in turn must be translated into better ways to prevent and treat diseases; all of this in order to achieve sustainable global human development. The much-needed North-South collaborative research for health has been on the rise in recent decades in response to the above. Due to various reasons, bioethical challenges and questions that must be addressed have arisen in this interaction. In this work we have identified: 1) asymmetry, 2) colonialism, 3) exploitation, 4) information , and 5) the research ethics committees, as the main challenges. Additionally, the bioethical aspects to be addressed have been reviewed. The urgency to build the bioethics of health research in cooperation between Northern and Sothern countries becomes evident.

Resumo: A pesquisa em saúde é essencial para enfrentar os desafios atuais e futuros mediante a geração de novos conhecimentos que, por sua vez, devem ter traduzidos em melhores formas de prevenir e tratar as doenças, a fim de atingir um desenvolvimento humano global duradouro. A tão necessária pesquisa colaborativa Norte-Sul em saúde tem aumentado nas últimas décadas como resposta a tudo isso. Por diversas razões, nessa interação vêm surgindo desafios e questionamentos bioéticos que devem ser enfrentados. Neste trabalho são identificados como os principais: 1) assimetria; 2) colonialismo; 3) exploração; 4) informação e 5) comitês de ética em pesquisa; além disso, são verificados os aspectos bioéticos que são necessários atender. É evidente a urgência de construir uma bioética da pesquisa em saúde em colaboração entre países do Norte e do Sul.

Asymptomatic infection with American cutaneous leishmaniasis: epidemiological and immunological studies

American cutaneous leishmaniasis (ACL) is a major public health problem caused by vector-borne protozoan intracellular parasites from the genus Leishmania, subgenera Viannia and Leishmania. Asymptomatic infection is the most common outcome after Leishmania inoculation. There is incomplete knowledge of the biological processes explaining the absence of signs or symptoms in most cases while other cases present a variety of clinical findings. Most studies of asymptomatic infection have been conducted in areas of endemic visceral leishmaniasis. In contrast, asymptomatic ACL infection has been neglected. This review is focused on the following: (1) epidemiological studies supporting the existence of asymptomatic ACL infection and (2) immunological studies conducted to understand the mechanisms responsible for controlling the parasite and avoiding tissue damage.

Animal models frr the study of leishmaniasis immunolggy / Modelos animales para el estudio de la inmunologia de la leishmaniosis

Leishmaniasis remains a major public health problem worldwide and is classified as Category I by the TDR/WHO, mainly due to the absence of control. Many experimental models like rodents, dogs and monkeys have been developed, each with specific features, in order to characterize the immune response to Leishmania species, but none reproduces the pathology observed in human disease. Conflicting data may arise in part because different parasite strains or species are being examined, different tissue targets (mice footpad, ear, or base of tail) are being infected, and different numbers (“low” 1×102 and “high” 1×106) of metacyclic promastigotes have been inoculated. Recently, new approaches have been proposed to provide more meaningful data regarding the host response and pathogenesis that parallels human disease. The use of sand fly saliva and low numbers of parasites in experimental infections has led to mimic natural transmission and find new molecules and immune mechanisms which should be considered when designing vaccines and control strategies. Moreover, the use of wild rodents as experimental models has been proposed as a good alternative for studying the host-pathogen relationships and for testing candidate vaccines. To date, using natural reservoirs to study Leishmania infection has been challenging because immunologic reagents for use in wild rodents are lacking. This review discusses the principal immunological findings against Leishmania infection in different animal models highlighting the importance of using experimental conditions similar to natural transmission and reservoir species as experimental models to study the immunopathology of the disease.

Las leishmaniosis siguen siendo un importante problema de salud pública a nivel mundial y se clasifican como categoría I por el programa TDR/WHO, debido principalmente a la ausencia de control. Muchos modelos experimentales tales como roedores, perros y monos han sido desarrollados, cada uno con características específicas, para caracterizar la respuesta inmune a las diferentes especies de Leishmania, sin embargo ninguno reproduce la patología observada en la enfermedad humana. La diversidad en los resultados obtenidos podría deberse en parte a que diferentes cepas de parásitos o especies están siendo examinadas, diferentes tejidos (cojinete plantar, oreja o base de la cola) han sido infectados y diferente número (“bajo” 1×102 y “alto” 1×106) de promastigotes metacíclicos han sido inoculados. Recientemente, nuevos enfoques han sido propuestos con el fin de obtener datos más significativos en cuanto a la respuesta inmune del huésped y a la patogénesis, de tal forma que reproduzcan lo que ocurre en la enfermedad humana. El uso de la saliva del insecto y de un número de parásitos menor en las infecciones experimentales ha permitido reproducir la transmisión natural, identificar nuevas moléculas, así como mecanismos inmunes que deberían ser considerados en el diseño de vacunas y estrategias de control. Adicionalmente, se ha propuesto como una buena alternativa el uso de roedores silvestres como modelos experimentales tanto para el estudio de las relaciones huésped-patógeno como para probar nuevas vacunas. A la fecha, el uso de reservorios naturales para estudiar la infección por Leishmania ha sido un reto, debido a la carencia de reactivos inmunológicos para uso en roedores silvestres. Esta revisión describe los principales hallazgos inmunológicos ante la infección por Leishmania, en los diferentes modelos animales, destacando la importancia del uso de condiciones experimentales similares a la transmisión natural y de reservorios como modelos experimentales para el estudio de la inmunopatología de la enfermedad.

Nitric oxide production by Peromyscus yucatanicus (Rodentia) infected with Leishmania (Leishmania) mexicana

Peromyscus yucatanicus (Rodentia: Cricetidae) is a primary reservoir of Leishmania (Leishmania) mexicana (Kinetoplastida: Trypanosomatidae). Nitric oxide (NO) generally plays a crucial role in the containment and elimination of Leishmania. The aim of this study was to determine the amount of NO produced by P. yucatanicus infected with L. (L.) mexicana. Subclinical and clinical infections were established in P. yucatanicus through inoculation with 1 x 10 2 and 2.5 x 10 6 promastigotes, respectively. Peritoneal macrophages were cultured alone or co-cultured with lymphocytes with or without soluble Leishmania antigen. The level of NO production was determined using the Griess reaction. The amount of NO produced was significantly higher (p ≤ 0.0001) in co-cultured macrophages and lymphocytes than in macrophages cultured alone. No differences in NO production were found between P. yucatanicus with subclinical L. (L.) mexicana infections and animals with clinical infections. These results support the hypothesis that the immunological mechanisms of NO production in P. yucatanicus are similar to those described in mouse models of leishmaniasis and, despite NO production, P. yucatanicus is unable to clear the parasite infection.

Preliminary study towards a novel experimental model to study localized cutaneous leishmaniasis caused bY Leishmania (Leishmania) mexicana / Estudio preliminar sobre un nuevo y original modelo experimental de leishmaniosis cutánea localizada causada por Leishmania (Leishmania) mexicana

There is not an experimental model of localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana. The aim of the present study was to characterize the clinical and histological features of Peromyscus yucatanicus experimentally infected with L. (L.) mexicana. A total of 54 P. yucatanicus (groups of 18) were inoculated with 1x10(6) promastigotes of L. (L.) mexicana in the base of the tail. They were euthanized at three and six months post experimental infection. The control group was inoculated with RPMI-1640. The predominant clinical sign observed was a single ulcerated lesion in 27.77% (5/18) and in 11.11% (2/18) P. yucatanicus at three and six months respectively. The histological pattern described as chronic granulomatous inflammation with or without necrosis was found in 7/7 (100%) biopsies of euthanized P. yucatanicus at three (n = 5) and six (n = 2) months, respectively. These results resembled clinical and histological features caused by L. (L.) mexicana in humans, and support the possibility to employ P. yucatanicus as a novel experimental model to study LCL caused by this parasite.

No existe un modelo experimental de la leishmaniosis cutánea localizada (LCL) causada por Leishmania (Leishmania) mexicana. El objetivo del presente estudio fue el de caracterizar los cuadros clínico e histológico de Peromyscus yucatanicus infectados experimentalmente con L. (L.) mexicana. Un total de 54 P. yucatanicus (grupos de 18) fueron inoculados en la base de la cola con 1x10(6) promastigotes de L. (L.) mexicana. A los 3 y 6 meses posteriores a la infección experimental fueron sacrificados. El grupo control fue inoculado con RPMI-1640. El signo clínico predominante fue una lesión única ulcerada en 27.77% (5/18) y en 11.11% (2/18) P. yucatanicus a los 3 y 6 meses respectivamente. El patrón histológico descrito como inflamación crónica granulomatosa con o sin necrosis se observó en 7/7 (100%) biopsias de los P. yucatanicus a los 3 (n=5) y 6 (n=2) meses respectivamente. Los resultados son similares a los cuadros clínico e histológico de la infección por L. (L.) mexicana en humanos, y apoyan la posibilidad de utilizar P. yucatanicus como un nuevo y original modelo para el estudio de la LCL causada por L. (L.) mexicana.

The histopathology of cutaneous leishmaniasis due to Leishmania (Leishmania) mexicana in the Yucatan peninsula, Mexico

La Leishmaniosis Cutánea Localizada (LCL) mejor conocida como "úlcera del chiclero" en el sureste de México fue descrita por SEIDELIN en 1912. Desde entonces la región selvática de la península de Yucatán ha sido identificada como un área endémica de LCL. En el presente estudio se analizaron 73 biopsias de lesiones de casos de LCL causados por Leishmania (Leishmania) mexicana con el fin de: 1) examinar la respuesta a nivel tisular; y 2) relacionar las manifestaciones de esta respuesta con ciertas características de la presentación clínica. Con base en la clasificación histopatológica de Magalhães el patrón histopatológico más frecuente se caracterizó por la presencia de granuloma desorganizado y ausencia de necrosis (43.83%). Otro hallazgo importante a señalar fue la presencia de parásito en 50/73 (68.5%) de las biopsias estudiadas. Respecto a las posibles relaciones significativas hubo una relación directa entre el tamaño de la lesión y el tiempo de evolución (rs = 0.3079, p = 0.03); una correlación inversa entre el tamaño de la lesión y la abundancia de promastigostes (rs = -0.2467, p = 0.03). Con base en la complejidad de los hallazgos clínicos e histopatológicos, consideramos necesario estudiar la respuesta inmune mediada por células relacionada con los cambios histopatológicos, así como el papel de los factores genéticos.

Seasonal transmission of Leishmania (Leishmania) mexicana in the state of Campeche, Yucatan Peninsula, Mexico

In the Yucatan Peninsula, Mexico, localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana is a typical wild zoonosis restricted to the forest, and humans are only accidentally involved. The transmission of L. (L.) mexicana has been related to the patient's occupation: chicleros(gum collectors) and agricultural workers. The objective of this study was to document L. (L.) mexicana seasonally of transmission in endemic areas of LCL in the state of Campeche, Yucatan Peninsula, Mexico. The timing of incidence of LCL in humans during 1993-1994, as well as the rate and time of infection in rodents and sand flies between February 1993 and March 1995 were analyzed. Rodents and sand flies were found infected between November and March, when men carried out their field activities and are exposed. Based on results analyzed, it is concluded that L. (L.) mexicana in the endemic area of LCL in the state of Campeche, Yucatan Peninsula, Mexico, presents a seasonal transmission restricted to the months of November to March. The knowledge of the timing of the transmission cycle in an endemic area of leishmaniasis is very important because intervention measures on the high-risk focus and population might be restricted.

Clinical picture of cutaneous leishmaniases due to Leishmania (Leishmania) mexicana in the Yucatan peninsula, Mexico

Localized cutaneous leishmaniasis (LCL), known as "chiclero's ulcer" in southeast Mexico, was described by Seidelin in 1912. Since then, the sylvatic region of the Yucatan peninsula has been identified as an endemic focus of LCL. The purpose of the present work was to describe the clinical picture of LCL caused by Leishmania (Leishmania) mexicana in the Yucatan peninsula. A total of 136 cases of LCL, based on isolation and characterization of L. (L.) mexicana by isoenzymes and/or monoclonal antibodies, were selected. Some variability of clinical features regarding number, type, size, form, location and time of evolution of the lesions was observed. The most frequently observed presentation was a single, ulcerated, rounded small lesion, located on the ear, with an evolution time of less than three months, with neither cutaneous metastases nor lymphatic nor mucosal involvement. This picture corresponds to previous studies carried out in the same endemic area where an organism of the L. mexicana complex has been incriminated as a major aetiological agent of classical "chiclero's ulcer", confirming that in the Yucatan peninsula LCL due to L. (L.) mexicana when located on the pinna of the ear is a remarkable characteristic

Retention of Leishmania (Leishmania) mexicana in naturally infected rodents from the State of Campeche, Mexico

In the State of Campeche, Mexico, zoonotic cutaneous leishmaniasis is mainly due to Leishmania (L.) mexicana. The parasite population is maintained in a mammalian species, a reservoir in which the ideal course of infection should be long and relatively nonpathogenic. The objective of the present study was to document the retention of L. (L.) mexicana in 29 naturally infected rodents. These cricetids lived in captivity for up to two years and were tested monthly for the presence of the parasite, by cultures of needle aspirates from the base of the tail. Peromyscus yucatanicus and Ototylomys phyllotis were incriminated as the primary reservoir hosts. The finding that the multiplication of parasites in P. yucatanicus might be triggered by temperature, suggests that this animal would be a good choice for further research on L. (L.) mexicana.

Use of monoclonal antibodies for the identification of Leishmania spp. isolated from humans and wild rodents in the State of Campeche, Mexico

The genus Leishmania includes 30 described species which infect a wide variety of mammalian hosts. The precise identification of leismanial parasites at the species level is very important in order to determine whether an organism, causing the disease in a given area, is of the same biotype as that found in suspected mammalian reservoir. the objectives of the present study were (1) to identify leismanial parasites isolated from humans and wild rodents from the State of Campeche, an endemic focus of localized cutaneous leishmaniasis (LCL) in southern Mexico, using an indirect immunofluorescent assay (IFA) with monoclonal antibodies (Mabs): and (2) to determine if the parasites of the two types of hosts wre of the same biotype. All the wild rodents (six Ototylomys phyllotis, eight Oryzomys melanotis, five Peromyscus yucatanicus and two Sigmodon hispidus) and 96 (por cento) (24/25) of the human isolates were identified as Leishmania (L.) mexicana confirming that this specific LCL focus is a wild zoonosis. The presence of one human isolate of L. (Viannia) braziliensis in the State of Campeche, conirmed the importance of an accurate taxonomic identification at species level.

Obtención de cultivo axénico de amastigotes de tres cepas de Leishmania (Leishmania) mexicana a partir de promastigotes aislados de pacientes con leishmaniasis cutánea localizada en México / Obtention of axenic cultivation of amastigotes of the three strains of Leishmania (Leishmania) mexicana using promastigotes isolated from patients with cutaneous leishmaniasis in Mexico

Introducción. La Leishmaniasis Cutánea Localizada, en la Península de Yucatán, es causada predominantemente por Leishmania (L.) mexicana. Las especies de Leishmania son parásitos intracelulares obligados dimórficos. Los promastigotes, formas flageladas y móviles, se replican y diferencian en el intestino del insecto vector. Los mastigotes, formas intracelulares inmóviles, viven dentro del fagolisosoma del macrófago huésped. Los amastigotes son más difíciles de obtener, debido a que se requieren ser aislados de tejidos y/o cultivos en líneas celulares de macrófagos. La alternativa es el cultivo axénico de formas de amastigotes. Material y métodos. El presente estudio describe la obtención de formas de amastigotes de tres cepas de Leishmania (L.) mexicana, (M/HOM/MX/94/VMC/663,M/HOM/MX/94/JM/758,M/HOM/MX/MX/95LPD/787), mediante la variación del pH y la temperatura de incubación en el medio de cultivo de Grace. Resultados. Los resultados mostraron un comportamiento diferente en cada cepa, determinado por la densidad celular y el porcentaje relativo de transformación. Los promastigotes de cada cepa se transformaron en más del 80 por ciento a formas de amastigotes al segundo día de incubación a pH 5.5 y temperatura de 35ºC. Por otro lado, la variación del pH, de 7.2 a 5.5 a 25ºC, permitió la transformación de promastigotes en metacíclicos. Conclusiones. La variación del pH y la temperatura de incubación permitió obtener las tres etapas de transformación del parásito (promastigotes, metacíclicos y amastigotes), los cuales podrán emplearse en futuros estudios bioquímicos e inmunológicos

A two years study on vectors of cutaneous leishmaniasis: evidence for sylvatic transmission cycle in the state of Campeche, Mexico

Vectors of cutaneous leishmaniasis in the State of Campeche were studied in relation to the transmission cycle of Leishmania (Le.) mexicana. To determine how transmission of leishmaniasis occurs, we collected phlebotomine sand flies for two years. In the first year (October 1990 to November 1991) the collections were made with CDC light traps, Shannon traps and direct captures at natural shelters around the village (<200m) of La Libertad. In the second year (February 1993 to January 1994) the catches were perfomed at 8 km southeast of La Libertad in the forest. Female sand flies were examined for Leishmania. During the first year, 347 sand flies of nine species were collected, most of which were Lutzomyia deleoni (61.3 per cent). When all nine species were considered, more females than males were captured. Low densities of anthropophillic species of sand flies around the village indicated that sylvatic transmission was taking place. For the second year, 1484 sand flies of 16 species were caught. The most common were L. olmeca olmeca (21.7 per cent), L. cruciata (19.2 per cent) and L. ovallesi (14.1 per cent). Similarly, more females were caught than males. Thirty-five females of five species were found infected with flagellates believed to be Leishmania sp. The highest infection rate was found in L. olmeca olmeca (7.1 per cent) followed by L. cruciata (4.5 per cent) and L. ovallesi (1.1 per cent). These data plus other evidence on the epidemiology of human cases and results from reservoir studies are discussed in relation to the sylvatic transmission cycle.

Population dynamics and biting rhythm of the anthropophilic sandfly Lutzomyia cruciata (Diptera: Psychodidae) in Southeast, Mexico

Flebotomo atraidos por cebo humano fueron conectados en un foco de leishmaniais cutanea localizada en el estado de Campeche, Mexico. Colectas fueron llevadas a cabo mensalmente de Febrero 1994 a Enero de 1995 entre las 18:00 a 22:00 h. Lutzomyia cruciata fue la unica especie capturada. El mayor pico plobacional fue encontrado en Marzo con picos similares en Febrero, Diciembre 1994 y Enero 1995. La tasa maxima de picadura de Lu. cruciata estuvo compreendida entre 18:00 e 19:00 h Las hembras hambientes de Lu. cruciata, fueron directamente relacionadas con niveles de humedad relativa entre 88 a 100 por cento. Bajas y altas temperaturas tuvieron un efecto negativo sobre la actividad de Lu. cruciata. Se discute el posible papel de Lu. criciata como vector de leishmaniasis en el estado de Campeche, Mexico

Induction of macrophage killing of Leishmania donovani by human CD4+ T cell clones

Immunitary in leishmaniasis is mediated by T cells, but protective responses in humans have not been fully defined. In this study, the functional activity of CD4+ T cell clones derived from an immune individual was investigated to identify potentially protective responses. The T cells proliferated and produced interferon-gamma (IFN-gamma) in response to a soluble Leishmania donovani antigen extrac and live amastigotes. There was considerable variation in the anti-leishmanial activity of the T cell clones when they were co-cultured with L. donavani infected monocytes isolated from an HLA-DR,DQ mathced donor. All of the clones which demonstrated antigen specific reactivity by proliferation or cytokineproduction induced some dregee of inhibition of intracellular parasite replication, but only a few of the clones induced pronounced leishmanicidal activity. There was strong correlation between the level of amastigote-induced IFN-gamma secretion and anti-leishmanial activity. This approach anables the identification of potentially protective immune responses in humans at the clonal level, and offers a means for the identification of the relevant antigen(s)