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.

The role of monocytes/macrophages in Leishmania infection: A glance at the human response.

Leishmania are obligate intracellular parasites of mononuclear phagocytes transmitted by Phlebotomine sandflies. Monocytes are one of the main cell types recruited to the site of the bite having an important role in the defense against Leishmania parasites in the first hours of infection. In the tissue, macrophages play a pivotal role as both the primary replication sites and the major effector cells responsible for parasite elimination. Many authors have reviewed the monocyte/macrophage-Leishmania interactions from results derived in mice, however, given the important differences between mice an humans we considered vital to discuss the role of these cells in human leishmaniasis. In this review, we recapitulated the most important studies carried out to understand the different roles of human monocyte/macrophages in Leishmania infection and how they can participate in both control and the immunopathogenesis of the disease.

Preliminary epidemiological findings of Leishmania infection in the municipality of Tinum, Yucatan State, Mexico.

Localized cutaneous leishmaniasis (LCL) is endemic in Mexico, mainly in the states of Campeche and Quintana Roo, hyperendemic areas of Leishmania (Leishmania) mexicana transmission. In this report, epidemiological features of Leishmania infections in the municipality of Tinum, Yucatan State, Mexico are presented. Nine cases of LCL were diagnosed in 2015. Patients were men between 30 and 74 years of age, without a history of living or traveling to endemic areas (Quintana Roo or Campeche). Due to asymptomatic infection is the most common outcome after Leishmania inoculation, between November 2017 to June 2018, 47 men working in the forest were tested by Montenegro skin test (MST). Thirteen of them (27.6%) were identified MST positive, in absence of either lesion or typical scar, and evidence of exposure to vector. Findings in Tinum, Yucatan, supported the presence of specific environmental conditions that seem to favor Leishmania transmission in this region. Thus, active surveillance for the detection of new cases in the municipality of Tinum as well as the eco-epidemiological characterization to identify all the transmission components (parasite, vector, and reservoir species) are urgently needed.

Finding a model for the study of Leishmania (Leishmania) mexicana infection: The Yucatan Deer mouse (Peromyscus yucatanicus) as a suitable option.

For more than four decades, the murine model has been employed extensively to understand immunological mechanisms associated with Leishmania infection. Although the use of laboratory mice has been very informative, mainly for L. (L.) major infection, the extrapolation to other Leishmania species and more importantly to human disease has been limited. Particularly in the case of L. (L.) mexicana, most infected mouse strains are highly susceptible and never presented asymptomatic infection, which is the main outcome in human. Thus, we postulated the use of Peromyscus yucatanicus, a primary reservoir of L. (L.) mexicana in the Yucatan Peninsula of Mexico, as an experimental model to study Leishmania infection. This rodent species can produce both asymptomatic and clinical infections therefore they seem more appropriate for studying host-pathogen interactions. In this review, we recapitulate the immunological findings observed in the traditional murine model of L. (L.) mexicana highlighting the differences with humans' infection and demonstrate the pertinence of P. yucatanicus as the experimental model for studying L. (L.) mexicana infection.

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.

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.

Cytokine mRNA expression in Peromyscus yucatanicus (Rodentia: Cricetidae) infected by Leishmania (Leishmania) mexicana.

Peromyscus yucatanicus, the main reservoir of Leishmania (Leishmania) mexicana in the Yucatan peninsula of Mexico, reproduces clinical and histological pictures of LCL in human as well as subclinical infection. Thus, we used this rodent as a novel experimental model. In this work, we analyzed cytokine mRNA expression in P. yucatanicus infected with L. (L.) mexicana. Animals were inoculated with either 2.5×10(6) or 1×10(2) promastigotes and cytokine expressions were analyzed by real-time RT-PCR in skin at 4 and 12weeks post-infection (wpi). Independently of the parasite inoculum none of the infected rodents had clinical signs of LCL at 4wpi and all expressed high IFN-γ mRNA. All P. yucatanicus inoculated with 2.5×10(6) promastigotes developed signs of LCL at 12wpi while the mice inoculated with 1×10(2) remained subclinical. At that time, both IFN-γ and IL-10 were expressed in P. yucatanicus with clinical and subclinical infections. Expressions of TNF-α and IL-4 were significantly higher in clinical animals (2.5×10(6)) compared with subclinical ones (1×10(2)). High TGF-ß expression was observed in P. yucatanicus with clinical signs when compared with healthy animals. Results suggested that the clinical course of L. (L.) mexicana infection in P. yucatanicus was associated with a specific local pattern of cytokine production at 12wpi.

In situ cytokines (IL-4, IL-10, IL-12, IFN-γ) and chemokines (MCP-1, MIP-1α) gene expression in human Leishmania (Leishmania) Mexicana infection.

Crucial to the defense against Leishmania is the ability of the host to mount a cell-mediated immune response capable of controlling and/or eliminating the parasite. The composition of the cell populations recruited in the early phase of the infection seems to be essential for defining the infection outcomes. The signals that initiate and regulate the early immune response and local accumulation of cell subsets in the skin are poorly understood. We previously studied the in situ expression of cytokine genes in patients with localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana. In the present study we examined in situ cytokine (IL-4, IL-10, IL-12, IFN-γ) and chemokine (MCP-1, MIP-1α) gene expression in L. (L.) mexicana active LCL lesions, and in the delayed type hypersensitivity (DTH) skin response to Leishmania antigen in subjects with healed lesion and subclinical infection. Data regarding cytokines were similar to previous studies in patients with active LCL. There were no significant differences in the profile of cytokine and chemokine gene expression in DTH from subjects with healed or subclinical infection. IL-12 gene expression detected in both groups was similar. High expression of MCP-1 was detected in all patients with active LCL. There was no difference in the level of MCP-1 expression between the healed lesion and the subclinical infection groups (p = 0.876). IL-12 and MCP-1 in the absence of IFN-γ might be playing a crucial role in infection outcomes at skin level.

Animal models for the study of leishmaniasis immunology.

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 × 10(2) and "high" 1 × 10(6)) 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.

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.

Cloning and sequence analysis of Peromyscus yucatanicus (Rodentia) Th1 (IL-12p35, IFN-γ and TNF) and Th2 (IL-4, IL-10 and TGF-ß) cytokines.

The Yucatan deer mouse, Peromyscus yucatanicus (order Rodentia), is the principal reservoir of Leishmania (Leishmania) mexicana in the Yucatan peninsula of Mexico. Experimental infection results in clinical and histopathological features similar to those observed in humans with cutaneous leishmaniasis (CL) as well as peritoneal macrophage production of nitric oxide. These results support the possible use of P. yucatanicus as a novel experimental model to study CL caused by L. (L.) mexicana. However, immunological studies in these rodents have been limited by the lack of specific reagents. To address this issue, we cloned and analyzed cytokine sequences of P. yucatanicus as part of an effort to develop this species as a CL model. We cloned P. yucatanicus interleukin 4 (IL-4), IL-10, IL-12p35, gamma interferon, transforming growth factor beta and tumor necrosis factor partial cDNAs. Most of the P. yucatanicus sequences were highly conserved with orthologs of other mammalian species and the identity of all sequences were confirmed by the presence of conserved amino acids with possible biological functions in each putative polypeptide. The availability of these sequences is a first step which will allow us to carry out studies characterizing the immune response during pathogenic and nonpathogenic L. (L.) mexicana infections in P. yucatanicus.

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.

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.

Preliminary study towards a novel experimental model to study localized cutaneous leishmaniasis caused by 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.

Reproductive characteristics of a captive colony of big-eared climbing rats (Ototylomys phyllotis).

The authors analyzed the breeding characteristics of a colony of Ototylomys phyllotis (big-eared climbing rat) from Campeche, México, that was bred in captivity for 6 y. The big-eared climbing rat is a reservoir of Leishmania (Leishmania) mexicana, a causal agent of localized cutaneous leishmaniasis on the Yucatán Peninsula. The colony had been established to facilitate studies analyzing the effectiveness of O. phyllotis as an experimental model for L. (L.) mexicana. The authors describe the housing and husbandry of the colony, the procedures used for mating the animals and the behavior of the animals during mating. They report that the animals showed social behavior and could be bred successfully. Most breeding pairs successfully produced litters; some pairs produced more than one litter. The authors also report data for other parameters, such as the interval between pairing and birth or between births of consecutive litters, litter size, survival to weaning, the timing of sexual maturity and the effects of breeder age on breeding success.

Leishmaniasis entomological field studies: ethical issues.

Occupational health remains neglected in developing countries because of competing social, economic and political challenges. Ethical issues in the workplace related to the hazards and risks of becoming infected by Leishmania (Leishmania) mexicana, through the bite of naturally infected sand flies, is another area of concern that has been neglected as well. We report here the results of reviewing two entomological field studies carried out in our research center from 2003 to 2006. Eight students from our School of Biology were invited to catch sand flies. A total of six of the eight (75%) developed a typical clinical picture of Localized Cutaneous Leishmaniasis (LCL) caused by L. (L.) mexicana. In this article we identify the ethical issues related to these kinds of studies and propose some guidelines for conducting them.

The histopathology of cutaneous leishmaniasis 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 documented as an endemic focus of LCL. This study of 73 biopsies from parasitological confirmed lesions of LCL cases of Leishmania (Leishmania) mexicana infection was undertaken: 1) to examine host response at tissue level; and 2) to relate manifestations of this response to some characteristics of clinical presentation. Based on Magalhães' classification we found that the most common pattern in our LCL cases caused by L. (L.) mexicana was predominantly characterized by the presence of unorganized granuloma without necrosis, (43.8%). Another important finding to be highlighted is the fact that in 50/73 (68.5%) parasite identification was positive. There was direct relation between the size of the lesion and time of evolution (rs = 0.3079, p = 0.03), and inverse correlation between size of the lesion and abundance of amastigotes (rs = -0.2467, p = 0.03). In view of the complexity of clinical and histopathological findings, cell-mediated immune response of the disease related to clinical and histopathological features, as so genetic background should be studied.

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.