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Background: Up to now, five cestode species have been reported infecting five hummingbird species. To date, there have been no reports of cestode infections in hummingbirds in Mexico., Methods: A Berylline hummingbird (Saucerottia beryllina) was found dead in a backyard at Toluca City, Mexico, and a window collision was assumed as the cause of death. The bird was preserved in 10% neutral buffered formalin for routine histological examination., Results: At the histological study, liver parenchymal disruption was observed. This lesion could be the result of the assume collision. No lesions were observed in other tissues examined. Conspicuous cestode structures were observed in the lumen of the small intestine. Structure of cestodes, as revealed from histological sections, suggests their position in the genus Anonchotaenia Cohn, 1900 (family Paruterinidae)., Conclusion: This is the first report of intestinal cestodosis in a Berylline hummingbird (S. beryllina) in Mexico., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

A new coccidian species, Isospora speciosae n. sp. (Apicomplexa: Eimeriidae) collected from the black-polled yellowthroat Geothlypis speciosa Sclater, is reported from the marsh Ciénegas del Lerma Natural Protected Area, Mexico. Sporulated oöcysts of the new species are subespherical to ovoidal, 24-26 × 21-23 (25.7 × 22.2) μm, with a length/width (L/W) ratio of 1.1; one or two polar granules are present, but micropyle and oöcyst residuum are absent. Sporocyts are ovoidal, 17-19 × 9-11 (18.7 × 10.2) μm, with a L/W ratio of 1.8; Stieda and sub-Stieda bodies are both present, but para-Stieda body is absent; sporocyst residuum compact. The new species is the sixth species of Isospora recorded in a bird of the family Parulidae in the New World., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

We examined 82 fresh fecal samples from American White Pelican (Pelecanus erythrorhynchos) at San Pablo Autopan, Toluca Valley, central Mexico, December 2021 to April 2022. Eggs of Contracaecum spp. were observed in 100%, Capillaria spp. in two (2.5%), Strongyloides spp. in eight (9.7%), and coccidial oocysts in 12 (15%)., (© Wildlife Disease Association 2023.)

The transmission of multidrug-resistant pathogens and antimicrobial resistance genes is an emerging problem involving multiple factors (humans, domestic animals, wildlife). The aim of this study was to investigate the presence of Escherichia coli isolates with different antimicrobial resistance genes from backyard poultry and to demonstrate the in vitro transduction phenomenon of these genes between phages from migratory wild birds and poultry E. coli isolates. We collected 197 E. coli isolates from chickens, turkeys, and ducks in backyard production units (northern region of the State of Mexico). Isolates were resistant to ampicillin (80.7%), tetracycline (64.4%), carbenicillin (56.3%), and nalidixic acid and trimethoprim-sulfamethoxazole (both, 26.9%). Moreover, the genes bla TEM (56.3%), tetB (20.8%), tetA (19.2%), sulI (7.6%), sulII (10.1%), qnrA (5.5%) were found. In vitro transduction using phages from migratory wild birds sampled in the wetland Chimaliapan (State of Mexico) was successfully achieved. It was possible to transduce qnrB (5.5%) were found. In vitro transduction using phages from migratory wild birds sampled in the wetland Chimaliapan (State of Mexico) was successfully achieved. It was possible to transduce qnrA , tetB , bla TEM , and sulII genes to E. coli isolates from poultry. This is the first report that describes the transduction of antimicrobial resistance genes from phages of migratory wild birds to poultry and suggests the possible transmission in backyard production units.

This is the first extensive report on the identification and characterization of Avibacterium paragallinarum (AVP) isolates obtained from outbreaks of infectious coryza (IC) in IC-vaccinated layer flocks from Sonora State in Mexico. Isolates obtained from IC outbreaks during the years 2007, 2014, 2015, 2017, and 2019 were identified by conventional PCR test and 16S rRNA gene analysis, serotyped by Page serotyping and genotyped by the recently described partial sequence analysis of the HPG2 region. Furthermore, antimicrobial susceptibility profiles were determined by a recently improved minimal inhibitory concentration (MIC) test. The conventional PCR test and the 16S rRNA analyses confirmed the isolates as AVP. Serotyping results showed the involvement of isolates belonging to serotypes A, B, and C in the IC outbreaks. Genotyping of the HPG2 region revealed the presence of sequence type (ST)1, ST4, and ST11, of which the latter has also been identified in Europe. The MIC susceptibility test showed that all tested isolates were susceptible for the majority of tested antimicrobials, including erythromycin and tetracycline, which are important antibiotics for the treatment of IC. The IC situation in Sonora State, Mexico, is complex because of the presence of serotypes A, B, and C. This finding emphasizes the importance of biosecurity in combination with the application of the most optimal vaccination programs in the control of IC in Sonora State, Mexico.

Up to now, four coccidian species have been identified in Rallidae (Aves: Gruiformes): Eimeria mongolica, E. alakuli, E. paludosa and E. porphyrulae. Here, we described an Eimeria species, E. paludosa, from a common gallinule (Gallinula galeata) in Mexico. Oocysts were ovoid and wall pitted single-layered. A prominent micropyle was present, the oocyst residuum absent and the polar granule was present. On histological examination of tissues, endogenous stages (meronts, microgametocytes and macrogametocytes) were seen in the epithelial cells of the small intestine (upper and lower intestine). In addition to a new locality, this is the first description of E. paludosa from G. galeata and is the third description of a coccidian infecting Rallidae in the Americas.

A new species of Acroeimeria Paperna & Landsberg, 1989 is described from Wiegmann's torquate lizard Sceloporus torquatus torquatus Wiegmann from Toluca, México. Oöcysts of Acroeimeria wiegmanni n. sp. are sub-spheroidal with a smooth bi-layered wall, measure on average 28.6 × 23.6 µm, and have a length/width (L/W) ratio of 1.2; a micropyle and an oocyst residuum are absent but polar granule(s) are present. Sporocysts are ellipsoidal and measure on average 11.7 × 8.6 µm, L/W 1.3; Stieda, sub-Stieda and para-Stieda bodies are absent. The sporocyst residuum is composed of numerous spheroidal granules in the center of the sporocyst. Endogenous stages of the new species develop in the duodenum of hosts. This is the first species of coccidian reported from S. t. torquatus and one of the few reported from a reptile in México.

Infectious pancreatic necrosis virus (IPNV) causes economic losses in Mexican rainbow trout industry. In this study, virulence and genetic fingerprints of Mexican IPNV isolates was investigated for the first time. Two Mexican IPNV isolates were analyzed in rainbow trout fry and the Sp strain was included as high virulence. One of the Mexican IPNV isolate was obtained from diseased fish and the other from fish without clinical signs. The infection was performed using a standardized immersion. Clinical signs were observed at 4 days post infection in fry group infected with strain Sp, two days earlier than in trout infected with IPNV isolates Mexican. Severe lesions were found in 100% of the individuals of Sp group, but only in 25% of each isolated Mexican group. Results suggest that Mexican IPNV isolates are pathogenic, but less virulent than strain Sp. The amino acid motif residues of both Mexican isolates, corresponded to a subclinical disease. Nevertheless, the accumulated motility observed in the field, suggest that other factors play a role in the virulence of the disease.

The members of the Aeromonas genus are important foodborne pathogens, with a worldwide distribution. Wild rainbow trout, from the national protected area Santuario del Agua State Park, Corral de Piedra, were analyzed. Species of Aeromonas were isolated from the trout, and their pathogenic potential was analyzed based on different pathogenicity and virulence factors. The isolates were identified as A. allosaccharophila ( n = 15), A. sobria ( n = 8), A. veronii ( n = 3), A. rivipollensis ( n = 2), A. piscicola ( n = 2), and A. popoffii ( n = 1), by RNA polymerase sigma factor ( rpoD ) gene sequencing. Sequence similarity with the type strain was 92.2 to 99.6% for A. sobria isolates, 97.8 to 98.0% for A. allosaccharophila isolates , 99.2% for the A. popoffii isolate, 99.2 to 100% for A. piscicola isolates, and 98.2 to 99.2% for A. veronii isolates. Notably, isolates A30T2-gills and A30T2-spleen showed sequence similarity of 98.0% with strain A. media CECT 4232T and 99.0% with strain A. rivipollensis P2G1T. Virulence genes were detected by PCR at the following frequencies: fla and serine protease, 96.77%; aerA, 93.54%; aexT, 87.09%; lipases, 74.19%; ascV and ahyB, 67.74%; exu, 61.29%; act, 41.93%; ascF-G, 38.70%; lafA, 32.26%; alt, 6.46%; aopP, 9.67%; and ast, 3.23%. These results indicate that several Aeromonas species had the potential pathogenicity to infect wild rainbow trout in the waterway created by the Corral de Piedra dam, suggesting they could be an emerging zoonotic pathogen.

A new coccidian species (Chromista: Sporozoa: Eimeriidae) collected from the northern saw-whet owl Aegolius acadicus (Gmelin) is reported from Mexico. Eimeria aegoliusia n. sp. has subspherical oöcysts, with smooth, bi-layered wall. Micropyle and oöcyst residuum are both absent and a polar granule is present. To date, eight species of Eimeria Schneider, 1875 have been described from strigiform birds. Mean dimensions of sporulated oöcysts (23.7 × 22.4 µm) and sporocysts (12.8 × 8.3 µm) appear to be considerably smaller than those from other Eimeria spp. with owl definitive hosts: E. atheni Chauhan & Jain, 1979; E. megabubonis Upton, Campbell, Weigel & McKown, 1990; E. spenotytoi Carini, 1939; E. strigis Kutzer, 1963; and E. varia Upton, Campbell, Weigel & McKown. Dimensions of these sporulated oöcysts appear to be larger than those in E. bemricki Averbeck, Cooney, Guarnera, Redig & Stromberg, 1998. The presence of polar granules and their number allowed differentiation from E. bubonis Cawthorn & Stockdale, 1981 and E. nycteae Volf, Koudela & Modry, 1999. This is the first description of an eimeriid coccidian infecting A. acadicus.

A new coccidian species (Protista: Apicomplexa: Eimeriidae) collected from the rufous-capped brush finch Atlapetes pileatus Wagler in the Nevado de Toluca Natural Protected Area, Mexico. Oöcysts of Eimeria pileata n. sp. are ellipsoidal, measuring on average 16.5 × 14.1 μm, with a smooth, bi-layered wall. Micropyle and oöcyst residuum are absent, but a polar granule is present. Sporocysts are ellipsoidal, measuring on average 9.0 × 5.4 μm. Stieda and sub-Stieda bodies are both present. A sporocyst residuum is present as a compact mass of granules. This is the third description of an eimeriid coccidian infecting passerines.

A new coccidian species (Protista: Apicomplexa: Eimeriidae) is described from the orange-crowned warbler Oreothlypis celata (Say) collected in the Nevado de Toluca National Park, Mexico at 3,000 metres above sea level. Isospora celata n. sp. has subspheroidal oöcysts, measuring 28.4 × 26.4 μm, with smooth, bi-layered wall c.1.2 μm thick. Micropyle and polar granule are absent, but oöcyst residuum is present as a compact mass. Sporocysts are ovoidal, 18.2 × 12.8 µm. Stieda body knob-like and sub-Stieda body irregular and barely discernible. Sporocyst residuum is composed of granules of different sizes. Sporozoites are vermiform with one refractile body and a nucleus. This is the third description of an isosporoid coccidian infecting a New World warbler.

Infectious pancreatic necrosis virus (IPNV) is one of the most important viruses in the Pacific salmon Oncorhynchus spp., Atlantic Salmon Salmo salar, and Rainbow Trout O. mykiss industry. This virus has been shown to produce high mortality among salmonid fry and juveniles, and survivors might become carriers. Since 2000, IPNV has affected Mexican Rainbow Trout culture, resulting in considerable economic losses. In the current study, molecular characterization of the VP2 gene of a number of Mexican IPNV isolates was done and the virus's phylogenetic relationships to IPNV reference strains were investigated. The phylogenetic analysis indicated that Mexican IPNV isolates are closely related to strains from the United States and Canada and that all Mexican IPNV isolates belong to genogroup 1. Furthermore, low genetic diversity was found between the Mexican isolates (identity, 95.8-99.8% nucleotides and 95.8-99.6% amino acids). The result of the analysis of the amino acid residues found at positions 217, 221, and 247 (alanine, threonine, and glutamic acid, respectively) could be associated with virulence, although the expression of virulence factors is more complex and may be influenced by the agent and host factors. The high percentage of identity among the VP2 genes from geographically distant IPNV isolates and the evidence of wide distribution in the country might have been facilitated by carrier trout. This hypothesis is supported by the identification of the amino acid threonine at position 221 in all Mexican isolates, a factor related to the carrier state for IPNV, as reported by other studies.

In this study, we found unsporulated coccidia oocysts in passerines from the Nevado de Toluca National Park, Mexico. We captured birds and took samples of their droppings during three field visits. We examined a total of 72 fecal samples and found unsporulated coccidia oocysts in 10 samples from five passerine species: Atlapetes pileatus (3), Cardelina ruber (1), Mniotilta varia (1), Oreothlypis celata (2) and Regulus calendula (3). This appears to be the first recorded study of unsporulated coccidia oocysts in passerine species from Mexico.

Between 2008 and 2010, 14 isolates of Avibacterium paragallinarum were identified as serovar C-1 in Mexico. All isolates were obtained from commercial laying hens suffering infectious coryza despite a history of vaccination. The enterobacterial repetitive intergenic consensus-based PCR genotyping showed that all isolates had a common pattern. Until recently, serovars A-1, A-2, B-1, and C-2 were the serovars prevalent in Mexico. Serovar C-1 has been identified in Japan and recently in the Americas in Ecuador. Our current study suggests that Av. paragallinarum serovar C-1 is an emerging serovar in Mexico. Our results also indicate that the Mexican isolates of Av. paragallinarum serovar C-1 may have a clonal relationship. Knowledge of the genetic diversity of Av. paragallinarum may be of value in understanding vaccine performance and identifying the best combination to achieve broader protection.

Trout farming is a growing aquaculture industry in Mexico, with stock mainly supplied by the importation of eyed eggs. The aim of the present study was to determine the frequency of bacterial isolations in farmed rainbow trout Oncorhynchus mykiss from Mexico. Sixty-five farms distributed among seven states of Mexico were included in the study. Individual samples from gills, liver, spleen, intestine, and kidney were obtained from 563 apparently healthy fish. In total, 371 bacterial isolates were recovered from sampled fish; isolates of the genera Aeromonas, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Plesiomonas, Pseudomonas, and Yersinia were identified. Aeromonads were the most frequently isolated bacteria. Renibacterium salmoninarum was not isolated from any of the sampled fish. Our results showed the presence of bacteria that are potential pathogens of both rainbow trout and humans.

The presence of infectious pancreatic necrosis virus (IPNV) in salmonids predominantly produces a high mortality rate in first-feeding fry. Genomic analysis of the vp2 gene sequence is most commonly used to determine the genetic diversity of IPNV isolates. Recently, information obtained from the vp1 gene allowed for efficient analysis of the genetic diversity of IPNV. In this study, the vp1 gene from a Mexican IPNV isolate was characterized and compared with IPNV isolates from Europe, North America, and Asia. The results indicate that the Mexican isolate is most closely related genetically to the 2310 strain from Spain.

The infectious pancreatic necrosis virus (IPNV) affects several species of freshwater and marine fish. In Mexico, IPNV has an important impact on farming of rainbow trout Oncorhynchus mykiss; however, IPNV distribution in Mexico is unclear. The diagnosis of IPNV is laborious; usually it is based on isolation tests in cell culture followed by immunological identification using techniques of serum neutralization, immunofluorescence, or enzyme-linked immunosorbent assay. It has recently been demonstrated that reverse transcriptase polymerase chain reaction (RT-PCR) is an adequate method for the detection of aquatic birnaviruses. However, its diagnostic use is still limited because very low titers of viable virus cannot be easily detected. In this study, a combination of short-time cell culture and multiplex RT-PCR was established for the diagnosis of IPNV in rainbow trout obtained from farms in the state of Mexico. Three primer sets were used in a single reaction in the multiplex RT-PCR to increase the probability of identifying all serotypes of IPNV serogroup A as well as to help prevent a false-negative result. This approach was able to identify samples with an IPNV concentration of just 0.01 tissue culture infective dose with 50% endpoint (TCID50)/mL, and it identified more infected fish than RT-PCR alone or first-passage cell culture alone. Moreover, this technique made the same identifications as second-passage cell culture but in approximately 30% of the time needed for second-passage cell culture. Consequently, the time and cost efficiency of IPNV diagnosis were greatly reduced.