Predicting the Impact of Climate Change on the Distribution of Rhipicephalus sanguineus in the Americas

Climate change may influence the incidence of infectious diseases including those transmitted by ticks. Rhipicephalus sanguineus complex has a worldwide distribution and transmits Rickettsial infections that could cause high mortality rates if untreated. We assessed the potential effects of climate change on the distribution of R. sanguineus in the Americas in 2050 and 2070 using the general circulation model CanESM5 and two shared socioeconomic pathways (SSPs), SSP2-4.5 (moderate emissions) and SSP2-8.5 (high emissions). A total of 355 occurrence points of R. sanguineus and eight uncorrelated bioclimatic variables were entered into a maximum entropy algorithm (MaxEnt) to produce 50 replicates per scenario. The area under the curve (AUC) value for the consensus model (\u3e0.90) and the partial ROC value (\u3e1.28) indicated a high predictive capacity. The models showed that the geographic regions currently suitable for R. sanguineus will remain stable in the future, but also predicted increases in habitat suitability in the Western U.S., Venezuela, Brazil and Bolivia. Scenario 4.5 showed an increase in habitat suitability for R. sanguineus in tropical and subtropical regions in both 2050 and 2070. Habitat suitability is predicted to remain constant in moist broadleaf forests and deserts but is predicted to decrease in flooded grasslands and savannas. Using the high emissions SSP5-8.5 scenario, habitat suitability in tropical and subtropical coniferous forests and temperate grasslands, savannas, and shrublands was predicted to be constant in 2050. In 2070, however, habitat suitability was predicted to decrease in tropical and subtropical moist broadleaf forests and increase in tropical and subtropical dry broadleaf forests. Our findings suggest that the current and potential future geographic distributions can be used in evidence-based strategies in the design of control plans aimed at reducing the risk of exposure to zoonotic diseases transmitted by R. sanguineus

Primer análisis filogenético de Ehrlichia canis en perros y garrapatas de México. Estudio preliminar

RESUMEN Objetivos. Caracterizar filogenéticamente Ehrlichia canis a partir de perros naturalmente infectados y sus garrapatas, mediante PCR y secuenciación del gene 16SrRNA para compararlos con diferentes aislados encontrados en el continente Americano. Material y métodos. Se colectaron muestras sanguíneas de 139 perros con manifestaciones clínicas sugestivas a Ehrlichiosis, y que estuvieran infestados con garrapatas; una parte del gene 16SrRNA, fue secuenciada y alineada junto con las 17 secuencias reportadas en los países de América. Se construyeron dos árboles filogenéticos utilizando el método de Máxima verosimilitud compuesta, y Máxima parsimonia. Resultados. Fueron positivos  a E. canis 25/139 (18.0%) perros y 29/139 (20.9%) garrapatas colectadas sobre los perros. Las manifestaciones clínicas presentadas fueron fiebre, astenia, depresión y vómito. Las garrapatas Rhipicephalus sanguineus, Dermacentor variabilis y Haemaphysalis leporis-palustris fueron positivas para E. canis. El análisis filogenético mostró que las secuencias 16SrRNA de Ehrlichia canis aisladas de perros y garrapatas en este estudio forman un tercer grupo que diverge de las secuencias de Sudamérica y EUA. Conclusiones. Es el primer análisis filogenético de E. canis en México. Hay diferencias entre las secuencias de este estudio, con las reportadas en otros países de Sudamérica y en EUA. Esta investigación sienta las bases para profundizar en el estudio de la variabilidad genética

Diversidad de aves en sitios con distinto uso de suelo en Nuevo Conhuas, Calakmul, México

Birds are one of the most important vertebrate groups for the ecosystems' functioning, because their functions include pollination and seed dispersal. Nevertheless, their communities and populations are affected by changes in the ecosystems. These modifications can be a reflection of land use, and for this reason it is important to analyze how sites with different land use and ground cover can have an influence on the birds' communities. For this study, we sampled birds from February to June 2017 using mist nets in sites with different land use conditions: a site inside the Calakmul Biosphere Reserve, two acahuales, one agricultural and one forested, and one livestock site. The diversity of communities was different in each one of the sampling sites. We identified that bird communities between acahuales and the Calakmul Biosphere Reserve had a greater similarity than the livestock site. The seeders guild and the generalist species were more abundant in the livestock site. There was a greater number of specialist birds with low abundances in the Calakmul Biosphere Reserve. 39% of the species were present in the Calakmul Biosphere Reserve, that was the site with the greater diversity (D1= 36.38), and livestock site was dominated by a lower number of species (D2= 3.88). The multivariate analysis showed that the vegetation type present in the sites influence the abundance of the bird species (Dev= 373.1, p= 0.001), and their families. The presence of shared species between the acahuales and the Calakmul Biosphere Reserve shows the importance of the conservation and regeneration of the acahuales because they are a transition stage that contributes to the recovery of some bird species present in mature jungles that are threatened or belong to a risk category.Las aves son uno de los grupos de vertebrados más importantes en el funcionamiento de los ecosistemas al cumplir con importantes funciones como la polinización o dispersión de semillas. Sin embargo, las comunidades y sus poblaciones se pueden ver afectadas por cambios en los ecosistemas. Estas modificaciones pueden ser reflejo de los diferentes usos de la tierra, por lo que es importante analizar cómo las áreas con diferentes usos de suelo y coberturas influyen en las comunidades de aves. Para este estudio, realizamos muestreos de aves de febrero a junio de 2017 utilizando redes de niebla en cuatro sitios con distintas condiciones de uso: un sitio con vegetación conservada (Reserva de la Biósfera de Calakmul), dos acahuales, uno agrícola, otro forestal y un sitio ganadero. La diversidad de las comunidades fue diferente en cada uno de los sitios muestreados, se identificó que las comunidades de aves en los acahuales y la Reserva de la Biósfera de Calakmul son más similares a las del sitio ganadero. El gremio de los semilleros y las aves generalistas fueron más abundantes en el sitio ganadero. El 39% de las especies estuvo presente en la reserva de Calakmul, que fue el sitio con la comunidad más diversa (D1= 36.38); el sitio ganadero estuvo dominado por un menor número de especies (D2= 3.88). Los análisis multivariados mostraron que el tipo de vegetación presente en los sitios influye en la abundancia de familias y especies de aves (Dev= 373.1, p= 0.001). La presencia de especies compartidas entre los acahuales y la Reserva de la Biósfera de Calakmul demuestra la importancia en la conservación y regeneración de acahuales ya que son estados de transición que ayudan a recuperar especies presentes en las selvas maduras y que se encuentren bajo alguna categoría de riesgo

Borrelia burgdorferi Infection and Cutaneous Lyme Disease, Mexico

Four patients who had received tick bites while visiting forests in Mexico had skin lesions that met the case definition of erythema migrans, or borrelial lymphocytoma. Clinical diagnosis was supported with histologic, serologic, and molecular tests. This study suggests the Borrelia burgdorferi infection is in Mexico

Species Distribution Models and Ecological Suitability Analysis for Potential Tick Vectors of Lyme Disease in Mexico

Species distribution models were constructed for ten Ixodes species and Amblyomma cajennense for a region including Mexico and Texas. The model was based on a maximum entropy algorithm that used environmental layers to predict the relative probability of presence for each taxon. For Mexico, species geographic ranges were predicted by restricting the models to cells which have a higher probability than the lowest probability of the cells in which a presence record was located. There was spatial nonconcordance between the distributions of Amblyomma cajennense and the Ixodes group with the former restricted to lowlands and mainly the eastern coast of Mexico and the latter to montane regions with lower temperature. The risk of Lyme disease is, therefore, mainly present in the highlands where some Ixodes species are known vectors; if Amblyomma cajennense turns out to be a competent vector, the area of risk also extends to the lowlands and the east coast

México: La ecología perfecta para garrapatas y sus enfermedades transmisibles

Las garrapatas son parásitos que pueden albergar agentes zoonóticos, el estudio de su microbioma nos indica que patógenos están circulando en una determinada región geográfica y en su fauna endémica

Implications of climate change on the distribution of the tick vector Ixodes scapularis and risk for Lyme disease in the Texas-Mexico transboundary region

BACKGROUND: Disease risk maps are important tools that help ascertain the likelihood of exposure to specific infectious agents. Understanding how climate change may affect the suitability of habitats for ticks will improve the accuracy of risk maps of tick-borne pathogen transmission in humans and domestic animal populations. Lyme disease (LD) is the most prevalent arthropod borne disease in the US and Europe. The bacterium Borrelia burgdorferi causes LD and it is transmitted to humans and other mammalian hosts through the bite of infected Ixodes ticks. LD risk maps in the transboundary region between the U.S. and Mexico are lacking. Moreover, none of the published studies that evaluated the effect of climate change in the spatial and temporal distribution of I. scapularis have focused on this region. METHODS: The area of study included Texas and a portion of northeast Mexico. This area is referred herein as the Texas-Mexico transboundary region. Tick samples were obtained from various vertebrate hosts in the region under study. Ticks identified as I. scapularis were processed to obtain DNA and to determine if they were infected with B. burgdorferi using PCR. A maximum entropy approach (MAXENT) was used to forecast the present and future (2050) distribution of B. burgdorferi-infected I. scapularis in the Texas-Mexico transboundary region by correlating geographic data with climatic variables. RESULTS: Of the 1235 tick samples collected, 109 were identified as I. scapularis. Infection with B. burgdorferi was detected in 45% of the I. scapularis ticks collected. The model presented here indicates a wide distribution for I. scapularis, with higher probability of occurrence along the Gulf of Mexico coast. Results of the modeling approach applied predict that habitat suitable for the distribution of I. scapularis in the Texas-Mexico transboundary region will remain relatively stable until 2050. CONCLUSIONS: The Texas-Mexico transboundary region appears to be part of a continuum in the pathogenic landscape of LD. Forecasting based on climate trends provides a tool to adapt strategies in the near future to mitigate the impact of LD related to its distribution and risk for transmission to human populations in the Mexico-US transboundary region

Evaluation of factors leading to poor outcomes for pediatric acute lymphoblastic leukemia in Mexico: a multi-institutional report of 2,116 patients

Background and aimsPediatric acute lymphoblastic leukemia (ALL) survival rates in low- and middle-income countries are lower due to deficiencies in multilevel factors, including access to timely diagnosis, risk-stratified therapy, and comprehensive supportive care. This retrospective study aimed to analyze outcomes for pediatric ALL at 16 centers in Mexico.MethodsPatients <18 years of age with newly diagnosed B- and T-cell ALL treated between January 2011 and December 2019 were included. Clinical and biological characteristics and their association with outcomes were examined.ResultsOverall, 2,116 patients with a median age of 6.3 years were included. B-cell immunophenotype was identified in 1,889 (89.3%) patients. The median white blood cells at diagnosis were 11.2.5 × 103/mm3. CNS-1 status was reported in 1,810 (85.5%), CNS-2 in 67 (3.2%), and CNS-3 in 61 (2.9%). A total of 1,488 patients (70.4%) were classified as high-risk at diagnosis. However, in 52.5% (991/1,889) of patients with B-cell ALL, the reported risk group did not match the calculated risk group allocation based on National Cancer Institute (NCI) criteria. Fluorescence in situ hybridization (FISH) and PCR tests were performed for 407 (19.2%) and 736 (34.8%) patients, respectively. Minimal residual disease (MRD) during induction was performed in 1,158 patients (54.7%). The median follow-up was 3.7 years. During induction, 191 patients died (9.1%), and 45 patients (2.1%) experienced induction failure. A total of 365 deaths (17.3%) occurred, including 174 deaths after remission. Six percent (176) of patients abandoned treatment. The 5-year event-free survival (EFS) was 58.9% ± 1.7% for B-cell ALL and 47.4% ± 5.9% for T-cell ALL, while the 5-year overall survival (OS) was 67.5% ± 1.6% for B-cell ALL and 54.3% ± 0.6% for T-cell ALL. The 5-year cumulative incidence of central nervous system (CNS) relapse was 5.5% ± 0.6%. For the whole cohort, significantly higher outcomes were seen for patients aged 1–10 years, with DNA index >0.9, with hyperdiploid ALL, and without substantial treatment modifications. In multivariable analyses, age and Day 15 MRD continued to have a significant effect on EFS.ConclusionOutcomes in this multi-institutional cohort describe poor outcomes, influenced by incomplete and inconsistent risk stratification, early toxic death, high on-treatment mortality, and high CNS relapse rate. Adopting comprehensive risk-stratification strategies, evidence-informed de-intensification for favorable-risk patients and optimized supportive care could improve outcomes

Infection of Anaplasma phagocytophilum and Ehrlichia spp. in Opossums and Dogs in Campeche, Mexico: The Role of Tick Infestation

In recent years, some tick-borne diseases such as anaplasmosis and ehrlichiosis became widespread worldwide, threatening the health of humans, domestic animals and wildlife. The aims of this study were to determine the presence of Anaplasma phagocytophilum, Ehrlichia canis, and Ehrlichia chaffeensis in 102 opossums (Didelphis spp.) and 44 owned free-ranging dogs in southeastern Mexico using a specific polymerase chain reaction (PCR). A. phagocytophilum was detected in opossums and dogs with a prevalence of 3 and 27%, respectively. E. canis was only present in 7% of dogs, while we didn't detect E. chaffeensis in any host. We report the first evidence of infections of A. phagocytophilum in Didelphis virginiana and D. marsupialis in Mexico. The infection rates and patterns we found of A. phagocytophilum suggest that dogs are more directly involved in the ecology of this pathogen than opossums. Despite the small prevalence found, our results are of public health concern because of the zoonotic capabilities of A. phagocytophilum, the high tick infestation rates found and because both opossums and free-ranging dogs can achieve high population densities in the region