Spatial distribution of Triatoma dimidiata peridomestic colonies modulated by distance between susceptible microhabitat patches.

Triatoma dimidiata is a vector of the hemoparasite Trypanosoma cruzi, the causal agent of Chagas disease. It settles reproductive colonies in the peridomicile of the premises. The peridomicile is comprised of a random set of artificial and natural features that overlap and assemble a network of microenvironmental suitable sites (patches) that interact with each other and favor the structure and proliferation of T. dimidiata colonies. The heterogeneity of patch characteristics hinders the understanding and identification of sites susceptible to colonization. In this study, a classification system using a random forest algorithm was used to identify peridomiciles susceptible to colonization to describe the spatial distribution of these sites and their relationship with the colonies of T. dimidiata in ten localities of Yucatan. From 1,000 peridomiciles reviewed, the classification showed that 13.9 % (139) of the patches were highly susceptible (HSP), and 86.1 % (861) were less susceptible (LSP). All localities had at least one HSP. The occupancy by patch type showed that the percentage of total occupancy and by colonies was higher in the HSP, while the occupancy by adult T. dimidiata without evidence of nymphs or exuviae (propagules) was higher in the LSP. A generalized additive model (GAM) revealed that the percentage of occupied patches increases as the abundance of individuals in the localities increases however, the percentage of occupied patches in LSP is lower than occupied in HSP. Distance analyses revealed that colonies and propagules were located significantly closer (approximately 200 m) to a colony in a HSP than any colony in a LSP. The distribution of T. dimidiata in the localities was defined by the distribution of patch type; as the occupancy in these patches increased, a network of peridomestic populations was configured, which may be promoted by a greater abundance of insects inside the localities. These results reveal that the spatial distribution of T. dimidiata individuals and colonies in the peridomicile at the locality scale corresponds to a metapopulation pattern within the localities through a system of patches mediated by distance and level of the vectors' occupancy.

Exposure to Trypanosoma cruzi and Leishmania parasites in dogs from a rural locality of Yucatan, Mexico. A serological survey.

Trypanosoma cruzi, the causal agent of American trypanosomiasis, and Leishmania spp., the causal agents of Leishmaniasis, are prevalent in more than 20 American countries, including Mexico. Dogs have been reported as incidental hosts for both parasites and may be helpful as transmission sentinels. We surveyed the dog population in a rural locality of the Merida municipality in Yucatan, Mexico, to evaluate the seroreactivity against T. cruzi and Leishmania spp. using two antigens, parasite homogenate (H) and iron superoxide dismutase extract (FeSODe), with two serological techniques (ELISA and Western Blot). Our study found that 3.33% of the tested dogs were seroreactive to T. cruzi using ELISA-H, and 29.5% were seroreactive to FeSODe antigen, with a 94.4% consistency between the two tests. Similarly, for L. mexicana, 1.6% were seroreactive using ELISA-H, and 9.8% were seroreactive using ELISA-FeSODe, with an 83.3% consistency between tests. For L. braziliensis, no dogs were seroreactive using ELISA-H, but 16.4% were seroreactive using ELISA-FeSODe, with a 90% consistency between tests. Finally, for L. infantum, 4.9% were seropositive using ELISA-H, and 6.6% were seropositive using ELISA-FeSODe, with a 75% consistency between tests. These results show noticeable evidence of exposure of dogs to trypanosomatid parasites and highlight the potential disease risk for the people and their companion animals in the region.

Cutaneous Leishmaniasis Emergence in Southeastern Mexico: The Case of the State of Yucatan.

Environmental changes triggered by deforestation, urban expansion and climate change are present-day drivers of the emergence and reemergence of leishmaniasis. This review describes the current epidemiological scenario and the feasible influence of environmental changes on disease occurrence in the state of Yucatan, Mexico. Relevant literature was accessed through different databases, including PubMed, Scopus, Google, and Mexican official morbidity databases. Recent LCL autochthonous cases, potential vector sandflies and mammal hosts/reservoirs also have been reported in several localities of Yucatan without previous historical records of the disease. The impact of deforestation, urban expansion and projections on climate change have been documented. The current evidence of the relationships between the components of the transmission cycle, the disease occurrence, and the environmental changes on the leishmaniasis emergence in the state shows the need for strength and an update to the intervention and control strategies through a One Health perspective.

Biomonitoring Organochlorine Pesticides in Didelphis virginiana from Yucatan, Mexico by GC-ECD.

The aim of the present work was to apply a validated methodology for the detection of organochlorine pesticides in Didelphis virginiana (Virginia opossum) serum samples collected in Yucatan, Mexico. Recent studies performed to investigate the presence of Organochlorines (OCLs) in water, human blood and milk, and animal tissues from Yucatan have shown that the OCLs concentrations are high and can be associated with potential human health risk. Since opossum is considered an important synanthropic species in Yucatan, 40 opossum serum samples were analyzed by gas chromatography with electron capture detector. The most common OCLs found in opossum sera were lindanes, chlordanes, drines, and endosulfan. Heptachlor, heptachlor epoxide, and lindanes were found at the highest concentrations, while dichlorodiphenyl trichloroethane and its metabolites were found at the lowest concentrations in the samples. The good linearity, precision, and accuracy obtained in the evaluated parameters in the extraction and chromatographic methods support its application for the monitoring of OCLs pesticides in populations of opossums and other wild species in Yucatan.

PHYSIOLOGICAL BASAL PARAMETERS OF FREE-RANGING OPOSSUMS ( DIDELPHIS VIRGINIANA) IN THE YUCATAN PENINSULA, MEXICO.

The aim of the present study is to determine the basal parameters in opossums ( Didelphis virginiana) during physical examination in Yucatan, Mexico. Sixty-six opossums were captured and manually handled for physical examinations. Sex, age, cardiac and respiratory rate, body temperature, pulse, mucous membranes, capillary refill time, hydration, size of superficial lymph nodes, mental status, and body condition were evaluated. Also, comparisons between rectal and auricular temperatures were performed. The means of physiological parameters obtained were: cardiac frequency 146 beats per minute (95% confidence interval [CI]: 138.91-155.24), respiratory frequency 27.33 breaths per minute (95% CI: 25.15-29.64), and body temperature 34.01°C (95% CI: 33.71-34.31). In 54% of animals, a sinus arrhythmia was present. A significant difference was found between rectal and auricular temperature measurements. A variation of -1.64 to 1.14°C was obtained via the auricular thermometer compared with the rectal device.

Class I-Restricted T Cell-Associated Molecule Is a Marker for IFN-γ-Producing iNKT Cells in Healthy Subjects and Patients with Type 1 Diabetes.

Class I-restricted T cell-associated molecule (CRTAM) is an activation marker expressed on the cell surface of activated invariant natural killer T (iNKT) cells, CD8+ T cells, and a small subset of CD4+ T cells. CRTAM has also been associated with a proinflammatory profile in murine CD4+ T cells. However, CRTAM has not been thoroughly explored in human cells. This work focused on evaluating CRTAM expression in human iNKT lymphocytes after activation with α-galactosylceramide, its widely used specific glycolipid antigen. We also analyzed the involvement of costimulatory molecules in CRTAM expression and whether CRTAM expression is associated with a specific effector cytokine profile. We found that the signal produced by invariant T cell receptor (iTCR) engagement with α-galactosylceramide is sufficient to trigger CRTAM expression on human iNKT cells after 18 h of stimulation. Moreover, we observed a clear association between CRTAM expression and IFN-γ production in iNKT cells from healthy subjects and patients with type 1 diabetes. However, blocking the engagement of costimulatory molecules, such as CD40, CD80, and CD86, did not modify CRTAM expression. These results indicate that CRTAM may also play a role in triggering the production of IFN-γ in human iNKT cells and that CRTAM could be used as a marker to identify these inflammatory cells.

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.