The Rhipicephalus sanguineus group encompasses at least 12 validated species of Palearctic and Afrotropical hard ticks, which are relevant in veterinary medicine and public health. The taxonomy of R. sanguineus s.s., has been particularly intensely debated, due to its wide geographic distribution, morphological variants, parasite-host associations, and its capacity and vectorial competence for the transmission of several pathogens. By sequencing mitochondrial markers, it was possible to identify the existence of multiple lineages, among which the Tropical and the Temperate lineages stand out, particularly in America. However, the northern limit between these lineages is not clear due to the lack of extensive sampling across Mexico. For this reason, the aim of the present study was to determine the genetic diversity and structure of the R. sanguineus group in Mexico and to compare it with the populations reported in the Americas, in order to propose the northern limit of the R. sanguineus Tropical lineage and the potential regions of sympatry with R. sanguineus s.s. The findings of this study now confirm the presence of R. sanguineus s.s. in Mexico, showing a subtle genetic structure and high genetic diversity throughout its distribution in the Americas. In contrast, the Tropical lineage seems to be genetically less diverse in its overall distribution in the Americas. The genetic diversity of these two independent lineages could have important epidemiological implications in the transmission of tick pathogens.

Resumen. Se proporcionan nuevos registros de distribución de las siguientes especies: Latrodectus mactans (Fabricius), L. geometricus C. L. Koch, Loxosceles boneti Gertsch, L. colima Gertsch & Ennik, y L. zapoteca Gertsch & Ennik, para 12 estados de la República Mexicana; así como una lista actualizada de la distribución geográfica de las especies incluidas en los géneros Latrodectus Walckenaer y Loxosceles Heineken & Lowe en México, ésto, con el propósito de conocer la actual distribución de estos arácnidos, ya que representan un importante riesgo en la salud pública en nuestro país por el creciente número de casos de intoxicación por su mordedura. New distribution records of Latrodectus mactans (Fabricius), L. geometricus C. L. Koch, Loxosceles boneti Gertsch, L. colima Gertsch & Ennik, and L. zapoteca Gertsch & Ennik for 12 states of Mexico are given; as well as an updated list of the distribution records of the species included of the genera Latrodectus Walckenaer and Loxosceles Heineken & Lowe in Mexico; with the purpose to describe the actual distribution of these arachnids because they represent an important issue in the public health in the country for the increasing number of cases because of their bites.

The Trypanosomatidae family encompasses around 24 genera of unicellular protozoans, many of which are transmitted by various hematophagous arthropods, particularly members of the Orders Diptera and Hemiptera. Fleas and ticks—an understudied group of ectoparasites—have been shown to be hosts of a wide and crescent variety of trypanosomatid species. Further, fleas and ticks of companion animals have been particularly neglected in trypanosomatid surveillance despite the proximity to human populations and the anthropophagous habits of many of these arthropods, which can potentially act as vectors of zoonotic trypanosomatids. We aimed to identify the presence, characterize the species, and establish the prevalence of Kinetoplastids, including members of the Trypanosomatidae family, in ectoparasites collected from dogs and humans from Mexico. A total of 537 ectoparasite specimens belonging to six ectoparasite taxa (Amblyomma mixtum, A. tenellum, Ctenocephalides felis felis, Pulex simulans, Rhipicephalus linnaei, and Rh. sanguineus s.s.) were collected from 15 States of Mexico. An 800 bp fragment of the 18S-rDNA gene from kinetoplastids was amplified and sequenced. The presence of two agents (Trypanosoma caninum and Parabodo sp.) was detected in R. linnaei ticks and one (Blechomonas lauriereadi) in the cat flea Ct. felis felis. This is the first record of genetic material of kinetoplastid species in ectoparasites from dogs and humans in Mexico.

In America, the presence of Rhipicephalus sanguineus sensu stricto and Rhipicephalus linnaei has been confirmed. Both species are found in sympatry in the southern United States, northern Mexico, southern Brazil, and Argentina. The objective of this work is to evaluate the projection of the potential distribution of the ecological niche of Rhipicephalus sanguineus sensu lato in two climate change scenarios in Mexico and the border with Central America and the United States. Initially, a database of personal collections of the authors, GBIF, Institute of Epidemiological Diagnosis and Reference, and scientific articles was built. The ENMs were projected for the current period and two future scenarios: RCP and SSP used for the kuenm R package, the ecological niche of R. sanguineus s.l. It is distributed throughout the Mexico and Texas (United States), along with the border areas between Central America, Mexico, and the United States. Finally, it is observed that the ecological niche of R. sanguineus s.l. in the current period coincides in three degrees with the routes of human migration. Based on this information, and mainly on the flow of migrants from Central America to the United States, the risk of a greater gene flow in this area increases, so the risk relating to this border is a latent point that must be analyzed.