Identification of SARS-CoV-2 in urban rodents from Southern Mexico City at the beginning of the COVID-19 pandemic

ABSTRACT Currently, there are some concerns about the situation and, in particular, about the future of the COVID-19 pandemic and the new emerging variants of SARS-CoV-2. Rodents are an example of synanthropic animals in urban environments that harbor important zoonoses. Although the molecular identification of SARS-CoV-2 in Rattus norvegicus from New York City had been reported, in other studies, urban wild rodents infected with this virus have not been found. This study aimed to molecularly identify the presence of SARS-CoV-2 in urban wild rodents from Mexico City, trapped along a water channel of a public park as part of a pest control program, at the beginning of the COVID-19 pandemic, during the fall and winter of 2020. Up to 33 Mus musculus and 52 R. norvegicus were captured and euthanized, large intestine samples with feces from the animals were obtained. RNAs were obtained and subjected to qRT-PCR for SARS-CoV-2 identification and threshold cycle (Ct) values were obtained. Four mice (12.1%) and three rats (5.8%) were positive, three rodents exhibited Ct<30. Our results on the frequency of SARS-CoV-2 in urban rats are in line with other previous reports. Thus, similar to other authors, we suggest that surveillance for the detection of SARS-CoV-2 in urban wild rodents, as sentinel animals, should be maintained.

Viral Prevalence in Wild Serval Population is Driven by Season and Sex.

One of the key factors influencing the population dynamics of threatened species such as felids is disease, but long-term studies of the factors influencing seroprevalence of wild felids are extremely rare, hindering conservation efforts. We set out to determine seroprevalence of six viral diseases (feline panleukopenia virus, feline leukemia virus, feline coronavirus, feline calicivirus, feline herpes virus, and feline immunodeficiency virus) among a population of serval (Leptailurus serval) with an extremely high density in South Africa. We captured 55 individuals over four years and screened blood samples for antibodies to each virus. We found that seroprevalence were high (ranging from 30.0% positive for a single virus to 1.8% positive for up to five viruses) and that seroprevalence was influenced by season and sex, but not body condition. We suggest further monitoring of this population and recommend that long-term studies are conducted for serval and other felids to determine whether these trends are representative on a broader scale.

The genus Rickettsia in Mexico: Current knowledge and perspectives.

The genus Rickettsia encompasses 35 valid species of intracellular, coccobacilli bacteria that can infect several eukaryotic taxa, causing multiple emerging and re-emerging diseases worldwide. This work aimed to gather and summarise the current knowledge about the genus Rickettsia in Mexico, updating the taxonomy of the bacteria and their hosts by including all the records available until 2020, to elucidate host-parasite relationships and determine the geographical distribution of each Rickettsia species present in the country. Until now, 14 species of Rickettsia belonging to four groups have been recorded in Mexico. These species have been associated with 26 arthropod species (14 hard ticks, three soft ticks, two sucking lice, and seven fleas) and 17 mammal species distributed over 30 states in Mexico. This work highlights the high biological inventory of rickettsias for Mexico and reinforces the need to approach the study of this group from a One Health perspective.

Morphometric differences in testicular tissue of tadarida brasiliensis bats from the urban area of Mexico City during summer, autumn, and winter / Diferencias morfométricas en parenquima testicular de murcielagos tadarida brasiliensis del área urbana de la Ciudad de México en verano, otoño e invierno

Most of the neotropical bats reproduce in a seasonal fashion. The purpose of this study was to assess changes in testicular tissue by morphometry, in Tadarida brasiliensis bat, in a south urban zone of Mexico City during summer, autumn, and winter. Three sample collections (February, June, and September) from T. brasiliensis were carried out (n=6). Testicle fragments were obtained for histological studies. Diameter of the seminiferous tubules and interstitial space were measured, cellular populations were identified and counted. June samples showed smaller diameter of seminiferous tubules and larger interstitial space between tubules; also there were less number of germinal epithelium cells and spermatids were absent. Tissues from September and February showed a significant increase (p 0.05) in tubule diameter, germinal epithelium thickness, and number of germinal epithelium cells when compared to June samples. Only February samples showed presence of spermatids. Our results suggest the existence of seasonal variations in the reproductive activity of T. brasiliensis, under conditions in which the study was conducted.

La mayoría de los murciélagos neotropicales se reproducen de manera estacional. El objetivo de este estudio fue determinar los cambios morfométricos en el parénquima testicular del murciélago Tadarida brasiliensis que habita en un área urbana del sur de la Ciudad de México durante las estaciones de verano, otoño e invierno. Se obtuvieron fragmentos de tejido testicular para su estudio histológico. Se midió el diámetro de los túbulos seminíferos y el espacio interstisial y se identificaron y contaron distintos tipos celulares. En las muestras de junio se encontró un menor diámetro de los túbulos seminíferos y un mayor espacio intersticial entre los túbulos; también hubo un menor número de células del epitelio germinal y no hubo presencia de espermátides. En las muestras de tejido obtenidas en el mes de septiembre y febrero se observó un incremento significativo en el diámetro del túbulo, grosor del epitelio germinal y número de células del epitelio germinal cuando fueron comparadas con las muestras de junio (p 0.05). Solo en las muestras de febrero hubo presencia de espermátides. En conjunto, nuestros resultados sugieren la existencia de variaciones estacionales en la actividad reproductiva de T. brasiliensis, bajo las condiciones en que se realizó el estudio.