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.

The genus Leptospira includes at least 69 Gram-negative, aerobic spirochetes, of which 25 are pathogenic and associated with a diverse range of mammals, including members of the order Chiroptera. On the American continent, there are six confirmed Leptospira species. Among these, the common vampire bat (Desmodus rotundus), which ranges widely from northern Mexico to northern Argentina, has been reported to harbor four pathogenic taxa: Leptospira borgpetersenii, Leptospira interrogans, Leptospira weilii, and Leptospira cf. noguchii. All these species are frequently isolated from beef and dairy cattle, suggesting that contact with urine from infected cattle could serve as a potential source of infection for bats. However, previous studies have been limited by small sample sizes and low geographical representation among the countries where they were conducted. For this reason, the aim of this study was to identify the species of Leptospira associated with D. rotundus populations in five states within the Neotropical region of Mexico. Between 2015 and 2021, 54 bats were collected across five Mexican states. Our analysis identified the exclusive presence of L. interrogans in 13 specimens. The findings are discussed within the framework of a One Health perspective, emphasizing their relevance to understanding interspecies transmission dynamics.

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae pose a significant public health risk. As zoos grow in popularity, exotic animals come into closer contact with humans, making them potential reservoirs of ESBLs. However, data on ESBL presence in Mexican zoos remains limited. For this reason, this study aimed to isolate and assess the antimicrobial susceptibility of Enterobacteriaceae that colonize avian species in a petting zoo and to identify any ESBL-producing isolates. Cloacal swabs were collected from 34 healthy birds at Miguel Angel de Quevedo Zoo, Veracruz, Mexico. Samples were analyzed microbiologically and molecularly to detect ESBL-encoding genes. A total of seventeen E. coli and one K. pneumoniae strains were isolated from cloacal swabs of bird species, and multidrug resistance (MDR) was found. The most frequently detected genes were bla_CTX-M-1 (16/18) and bla_TEM-1 (12/18). The detection of multidrug-resistant (MDR) strains carrying bla_CTX-M-1, bla_TEM-1, and bla_SHV genes highlights the potential role of birds as reservoirs and disseminators of antimicrobial resistance (AMR) in urban environments. To the best of our knowledge, this is the first study conducted in Mexico. In conclusion, MDR ESBL-producing bacteria were found in the fecal microbiota of bird species at a petting zoo in Mexico. The limitations of this study emphasize the need for a One Health approach to analyze the genome-wide isolates and epidemiology of antimicrobial-resistant bacteria in captive zoo animals in Mexico. This would support targeted surveillance efforts and help reduce the emergence and spread of resistant bacteria among zoo animals and visitors.

Soft ticks represent a neglected group of ectoparasites associated with a wide range of vertebrates. In México, 24 species have been reported, the majority parasitizing bats. Several species are competent vectors of a wide range of pathogenic microorganisms. For this reason, the aim of the present work was to identify ticks associated with bats from Tuxpan de Rodriguez Cano, Veracruz, México. Bats were captured using mist nets and were visually inspected for tick presence. The ectoparasites were identified morphologically and molecularly with the use of the mitochondrial marker 16SrDNA, and molecular detection of several bacterial and protozoan pathogens was also performed. Twenty-five bats of 9 species were inspected. We collected 7 tick larvae morphologically identified as Ornithodoros hasei from a female black-winged little yellow bat (Rhogeessa tumida). Sequencing of the 400-bp fragment of the 16S rDNA gene, demonstrated a similarity of 96 % (373/388 bp) with O. hasei from Argentina and Brazil. In addition, the presence of Coxiella sp. was confirmed. Our findings provide relevant information on the biology of O. hasei by identifying R. tumida as a new host, providing the most north-eastern record for the geographical distribution of this tick in the Gulf of México and detecting the presence of a new endosymbiont in this tick.

Sheep production in Mexico encounters notable challenges, among which infectious diseases stand out as a growing concern. Ovine respiratory syndrome (ORS) is particularly problematic, being a leading cause of economic losses in the industry. However, despite its significant negative impact, there remains a lack of comprehensive understanding regarding the microorganisms involved. For this reason, the aim of this study was to isolate and identify the causal agents responsible for a respiratory disease outbreak in a sheep production unit in Northern Veracruz. This included: collection of samples from affected sheep, focusing on those displaying clinical signs of respiratory illness; microbial culturing and molecular identification of the isolated bacteria. We isolated rounded, raised colonies with a pink mucoid aspect which were molecularly identified as Enterobacter hormaechei, which exhibited a similarity of 99.59% with sequences from China. The isolation and molecular identification of E. hormaechei provide new insights into the pathogens affecting sheep, highlighting the importance of continuous surveillance and research in improving sheep health and production. This study represents a significant step in identifying and understanding the causal agents of ORS in Northern Veracruz.