Free-ranging and feral dogs represent a group of unattended companion animals. They impact wild animal populations by predating native species, displacing predators and introducing exotic pathogens. The aim of this work was to describe the molecular occurrence of Rickettsia, Ehrlichia, Anaplasma, Mycoplasma and Bartonella in feral dogs. The study was carried out in the last relict of a protected area in Mexico City. Blood clots samples from 19 dogs were obtained and analyzed for detection of specific fragments of the 16S-rRNA gene for Anaplasma, Ehrlichia and Mycoplasma and citrate synthase (gltA) for Bartonella and Rickettsia. Our results showed that DNA from three bacteria species (Bartonella vinsonii subsp. berkhoffii, Ehrlichia canis and Mycoplasma haemocanis) was present with frequencies ranging from 5.3 to 15.8%. This is the first record of B. vinsonii subsp. berkhoffii and M. haemocanis in dogs from México, and also the first finding of Ehrlichia canis in Mexico City. It is important to perform surveillance of feral dog populations in order to identify the impact of these pathogens on wild animal populations and Public Health in order to establish prevention and protection programs.

La leptospirosis es la enfermedad zoonótica más ampliamente distribuida a nivel mundial, la cual es causada por 17 especies de espiroquetas del género Leptospira. Los miembros patógenos de este género bacteriano se relacionan con una amplia gama de hospederos vertebrados, en particular con cánidos, en los cuales pueden generar un amplio abanico de signos clínicos. Dado que se ha identificado que los perros fungen como una unidad centinela que permite identificar el grado de diseminación de estas bacterias en el medio, la vigilancia epidemiológica resulta prioritaria en estos hospederos. Por ello, el objetivo del presente trabajo fue identificar la seropositividad de la leptospirosis en cánidos de libre rango y ferales en una reserva ecológica urbana en la Ciudad de México, y explorar sus implicaciones en salud pública y medicina de la conservación. Se obtuvieron muestras de suero de 19 caninos, a los cuales se realizó la prueba de aglutinación microscópica (MAT, por sus siglas en inglés). El porcentaje de anticuerpos anti–Leptospira spp. en perros ferales fue de 100 % (IC 95 % 82,3–100), con una seroreactividad para tres serovariedades. Este es el primer trabajo realizado que identifica el grado de exposición a Leptospira spp. en perros ferales en México, en particular en una reserva ecológica.

Las redes de interacción entre mamíferos y pulgas son una herramienta útil para monitorear la transmisión de enfermedades. Pero estas redes se desconocen en la mayoría de los ambientes, particularmente en áreas urbanas. Por lo tanto, el objetivo de este artículo es construir una red de interacción entre mamíferos medianos y pulgas en la Reserva Ecológica del Pedregal de San Ángel (REPSA), una reserva urbana en la Ciudad de México. Agrupamos información de pulgas encontradas sobre mamíferos medianos de seis proyectos realizados entre 2019 y 2022. Con base en estos datos, construimos una red de interacciones entre pulgas y hospederos. Los mamíferos de la REPSA tienen pocas pulgas por hospedero (con un máximo de 7.9 en promedio en los cacomixtles; Bassariscus astutus), en comparación con otras áreas urbanas. La pulga más común y con mayor conectividad fue Ctenocephalides felis. El ardillón (Otospermophilus variegatus) es el mamífero menos conectado en la red. Concluimos que la infestación en nuestro sitio de estudio es baja en comparación con otras áreas urbanas, los monitoreos epidemiológicos deben concentrarse en C. felis y las enfermedades que esta pueda transmitir y que se requieren más estudios sobre roedores.

Species of the genus Hepatozoon are among the most widespread haemogregarine parasites infecting reptiles; however, information regarding their occurrence in native snakes from Mexico remains scarce. This study investigated the molecular occurrence of Hepatozoon spp. in free-ranging Mexican black-tailed rattlesnakes (Crotalus molossus nigrescens) rescued within the Reserva Ecológica del Pedregal de San Ángel (REPSA), an urban protected area in central Mexico. Opportunistically sampled squirrels were also included to explore the occurrence of these parasites in sympatric mammals. Blood samples from 26 rattlesnakes, six Mexican gray squirrels (Sciurus aureogaster), and three rock squirrels (Otospermophilus variegatus) were screened by PCR targeting a partial fragment of the 18S rRNA gene. Hepatozoon spp. DNA was detected in six rattlesnakes (23.1%) and two Mexican gray squirrels (33.3%), whereas all rock squirrels tested negative. Phylogenetic analyses suggested the presence of two distinct Hepatozoon lineages: one showing phylogenetic affinity with Hepatozoon cf. ophiosauri, detected in all positive rattlesnakes and one squirrel, and another closely related to Hepatozoon griseisciuri, identified in a second squirrel. These findings represent the first molecular detection of Hepatozoon in C. molossus nigrescens, the first record of infection in S. aureogaster, and the first report of a H. griseisciuri-like lineage in Mexico. Although parasite identification was based exclusively on partial 18S rRNA gene sequences, this study expands current knowledge of Hepatozoon diversity in Mexican wildlife and provides important baseline information for future studies integrating molecular, morphological, and ecological approaches to better understand parasite diversity and transmission in protected urban ecosystems.

Brucellosis is a neglected zoonotic disease that has become economic losses in the live- stock sector. Although attention has focused on domestic animals, wildlife can serve as a reservoir for several species of the genus Brucella, which is related to the emergence of the disease in areas affected by ecological changes caused by urbanization. In Mexico, although brucellosis is a disease that must be reported in both livestock and humans, there are few studies focused on wildlife. The aim of this research was to perform a serological diagnosis on 77 opossums (Didelphis virginiana) captured in a protected natural area in Mexico City during the period 2016-2018. The serum samples were analyzed using two serological tests: ABATEST 3% (PRONABIVE®) for animals and the Rose Bengal plate test (MICSA®), which is also used for human diagnosis. The results obtained using ABA TEST 3% indicated 18 positive cases (23.4%; 95%CI: 14.8-34. 6), while Rose Bengal showed 15 positives (19.5%; 95% CI: 11.6-30.4); however, in both tests, six samples were positive (7.7%; 95%CI: 3.2-16.8). The identification of antibodies against Brucella sp. in opossums provides initial evidence of exposure to this pathogen in wildlife inhabiting urban environments; however, the findings suggest that opossums may be involved in the transmission dynamics of Brucella sp. It is essential to consider cross-reactions with other pathogens, which reduce the specificity of serological tests, although these results highlight the need to integrate synanthropic wildlife into epidemiological surveillance and emphasize the importance of preventing and controlling zoonotic diseases.