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The article presents a case report of the isolation and identification of Avibacterium paragallinarum serovar B-1 from severe infectious coryza outbreaks in broiler breeders in Panama. Researchers characterized disease outbreaks by an up to 45 percent drop in egg production and increased mortality. The use of a commercial trivalent bacterin and a strengthened biosecurity program prevented outbreaks in susceptible flocks.

A new coccidian species, Eimeria atricillae n. sp. (Apicomplexa: Eimeriidae) collected from the laughing gull Leucophaeus atricilla, is reported from Port Isabel, Texas, USA. Sporulated oöcysts of the new species are spherical to subspherical, 16.0-18.1 × 14.4-16.6 (17.1 × 15.4) μm, with a length/width (L/W) ratio of 1.0-1.1; polar granules are present, but micropyle and oöcyst residuum are absent. Sporocysts are ovoid, 9.1-9.7 × 6.1-7.1 (9.4 × 6.6) μm, with a L/W ratio of 1.3-1.5; Stieda body present, but sub-Stieda and para-Stieda bodies are absent; sporocyst residuum diffuse., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

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 (9.6%), and 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.

Nematodes of the Anisakidae family have the ability to infest a wide variety of aquatic hosts during the development of their larval stages, mainly marine mammals, aquatic birds, such as pelicans, and freshwater fish, such crucian carp, these being the hosts where the life cycle is completed. The participation of intermediate hosts such as cephalopods, shrimp, crustaceans and marine fish, is an important part of this cycle. Due to morphological changes and updates to the genetic information of the different members of the family, the purpose of this review was to carry out a bibliographic search of the genus and species of the Anisakidae family identified by molecular tests, as well as the geographical area in which they were collected. The Anisakidae family is made up of eight different parasitic genera and 46 different species. Those of clinical importance to human health are highlighted: Anisakis pegreffi , A . simplex sensu stricto , Contracaecum osculatum , Pseudoterranova azarazi , P . cattani , P . decipiens and P . krabbei . The geographical distribution of these genera and species is located mainly in the European continent, Asia and South America, as well as in North and Central America and Australia. Based on the information collected from the Anisakidae family, it was determined that the geographical distribution is affected by different environmental factors, the host and the ability of the parasite itself to adapt. Its ability to adapt to the human organism has led to it being considered as a zoonotic agent. The disease in humans manifests nonspecifically, however the consumption of raw or semi-raw seafood is crucial information to link the presentation of the parasite with the disease. The use of morphological and molecular tests is of utmost importance for the correct diagnosis of the genus and species of the Anisakidae family.

Isospora dipperia n. sp. is described from the feces of the American dipper Cinclus mexicanus Swainson collected in Yosemite National Park, California, USA. Sporulated oöcysts of the new species are subespherical, 20-24 × 17-21 (20.9 × 18.7) μm, with a length/width (L/W) ratio of 1.0-1.1 (1.1); one polar granule is present, but micropyle is absent. Sporocyts are lemon-shaped, 14-16 × 8-11 (15.5 × 9.8) μm, with a L/W ratio of 1.6; prominent Stieda and sub-Stieda bodies are both present, but para-Stieda body is absent. Sporocyst residuum of many scattered granules is present and the sporozoites have prominent anterior and posterior refractile bodies. The mean dimensions (15.9 × 13.8 µm) of unsporulated oöcysts of I. cincli Gottschalk, 1972 from the white-throated dipper C. cinclus (L.) in Europe, appear to be considerably smaller than those in I. dipperia n. sp. Comparisons of Isospora dipperia n. sp. with two species of Isospora Schneider, 1881 described in the Americas from birds of the family Sturnidae, related to Cinclidae, revealed that the mean dimensions of the sporulated oöcysts in the new species are considerably smaller than those in I. graculai Bhatia, Chauhan, Arora & Agrawal, 1973 from Gracula religiosa (24.6 × 22.4 µm) and I. rothschildi Upton, Wilson, Norton & Greiner, 2001 from Leucopsar rothschildi (22.3 × 21.6 µm). The new species is the first species of Isospora recorded in a bird of the family Cinclidae in the New World.

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.

Haemosporidian parasites of birds are found worldwide and include the genera Haemoproteus , Plasmodium and Leucocytozoon . Infection with haemosporidian parasites can affect host physical condition and reproductive success. The aim of this study was to identify the blood parasites and parasitaemia in endemic and non-endemic passerine birds from central Mexico highlands. This study included 157 passerines representing 29 species from 17 families. Overall, 30.6% (48/157) of the birds were infected with blood parasites. Of those, Haemoproteus spp. were found in 14.0% (n = 22), Leucocytozoon spp. 12.1% (n = 19) and microfilariae 0.6% (n = 1). Blood parasites were found in 71.4% (5/7) of endemic bird species and 45.4% (10/22) of non-endemic species. Medium to high parasitaemia (number of parasites/number erythrocytes) was observed in birds with infections of Haemoproteus spp. and Leucocytozoon spp. Co-infections 3.8% (n = 6) were observed in two species of endemic birds. This study contributes to the knowledge of haemoparasites in endemic and non-endemic passerine birds from central Mexico highlands. Additional investigation on the molecular identification of haemosporidian parasites, pathogenicity and health status of these birds is necessary., Competing Interests: The authors declare no conflict of interest., (© 2020 The Author(s).)

Isospora phainopepla n. sp. is described from the faeces of Phainopepla nitens (Swainson) collected in Joshua Tree National Park, California, USA. To our knowledge, there are no metazoan or protist parasites described yet from any species in the Ptiliogonatidae of the Americas. Sporulated oöcysts of the isosporan are ellipsoidal, 30-35 × 22-29 (32.9 × 25.4) μm, with a length/width (L/W) ratio 1.20-1.35 (1.30); one rice-shaped polar granule is present, but both oöcyst residuum and micropyle are absent. Sporocyts are elongate-ellipsoidal, 22-27 × 11-14 (23.9 × 12.0) μm, with L/W ratio 1.97-2.02 (2.00); prominent Stieda and sub-Stieda bodies are both present, but para-Stieda body is absent. Sporocyst residuum of many scattered granules is present and the sporozoites have prominent anterior and posterior refractile bodies. This parasite is clearly new to science and represents the first species of Isospora hosted by a New World bird species from this small family of silky flycatchers (Ptiliogonatidae). This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as 7F664B0D-DF0E-4CAD-8CEA-45D79C8BBF92. This article was published as an Online First article on the online publication date shown on this page. The article should be cited by using the doi number. This is the Version of Record.

Isospora toxostomai n. sp. (Apicomplexa: Eimeriidae) is described based on material from the curved-billed thrasher Toxostoma curvirostre (Swainson) in the Central Highlands of Mexico. The new species possesses subspherical oöcysts, with a smooth, bi-layered wall. Sporulated oöcysts measure 22-25 × 21-24 (23.4 × 22.3) µm; length/width (L/W) ratio of 1.0-1.1 (1.1). Sporocysts are ellipsoidal, 15-17 × 10-11 (15.8 × 10.5); L/W ratio of 1.3-1.6 (1.5). Micropyle and oöcyst residuum are both absent, and a polar granule present (many fibrils). Mean dimensions of both sporulated oöcysts and sporocysts of I. toxostomai n. sp. appear to be considerably larger than those of Isospora mimusi Coelho, Berto, Neves, Oliveira Flausino & Lopes, 2011 from the tropical mockingbird Mimus gilvus (Vieilot) in Brazil. This is the second species of Isospora Schneider, 1881 infecting a host of the Mimidae in the Americas.

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.

The bacterium Ornithobacterium rhinotracheale is associated with respiratory disease in wild birds and poultry. In this study, the phylogenetic analysis of nine reference strains of O. rhinotracheale belonging to serovars A to I, and eight Mexican isolates belonging to serovar A, was performed. The analysis was extended to include sequences from another 23 strains available in the public domain. The analysis showed that the 40 sequences formed six clusters, I to VI. All eight Mexican field isolates were placed in cluster I. One of the reference strains appears to present genetic diversity not previously recognized and was placed in a new genetic cluster. In conclusion, the phylogenetic analysis of O. rhinotracheale strains, based on the 16S rRNA gene, is a suitable tool for epidemiologic studies.

Eimeria pileata Soriano-Vargas, Medina, Salgado-Miranda, García-Conejo, Galindo-Sánchez, Janczur, Berto and Lopes, 2015 is a junior homonym of Eimeria pileata Straneva and Kelley, 1979 and needs to be replaced. This coccidium was described from a rufous-capped brush finch Atlapetes pileatus Wagler in the Nevado de Toluca Natural Protected Area, Mexico. Thus, to maintain the original intent of the specific epithet derived from the scientific name of the type-host, the name Eimeria atlapetesi nom. nov. is proposed as a replacement name. Additionally, the current work reports another rufous-capped brush finch A. pileatus parasitized by E. atlapetesi in co-infection with an Isospora sp., providing observations of histopathology and phylogenetic analysis of 18S ribosomal RNA (rRNA) gene from E. atlapetesi. Endogenous forms of E. atlapetesi and Isospora sp. were observed in intestinal sections. Few oocysts of Isospora sp. were observed; therefore they were not morphologically or molecularly identified. In return, E. atlapetesi was identified and it was phylogenetically close to Eimeria dispersa Tyzzer, 1929 from the domestic turkey Meleagris gallopavo Linnaeus.

A new coccidian species (Protozoa: Apicomplexa: Eimeriidae) collected from the red warbler Cardellina rubra (Swainson) is reported from the Nevado de Toluca National Park, Mexico. Isospora cardellinae n. sp. has subspherical oöcysts, measuring on average 26.6 × 25.4 μm, with smooth, bi-layered wall, c.1.3 μm thick. Micropyle, oöcyst residuum, and polar granule are absent. Sporocysts are ovoidal, measuring on average 19.0 × 12.0 µm, with a knob-like Stieda body, a trapezoidal sub-Stieda body and sporocyst residuum composed of scattered spherules of different sizes. Sporozoites are vermiform with one refractile body and a nucleus. This is the fourth description of an isosporoid coccidian infecting a New World warbler.

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.

This study describes the macroscopic and microscopic lesions in farmed rainbow trout (Oncorhynchus mykiss) naturally infected with genetically identified Aeromonas salmonicida, A. hydrophila, and A. veronii species. The genus Aeromonas includes bacteria that naturally inhabit both waterways and organisms. At least 27 Aeromonas species have been identified to date, some of which can cause significant economic losses in aquaculture. As up to 68.8% of Aeromonas isolates may be misidentified in routine biochemical and phenotypic tests, however, reported cases of Aeromonas infection in fish may be wrongly identified. Our findings confirmed that the 3 Aeromonas species studied are associated with septicemia and dermal lesions in rainbow trout.

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.

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.

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.

Since 1970, aquaculture production has grown. In 2010, it had an annual average rate of 6.3% with 59.9 million tons of product and soon could exceed capture fisheries as a source of fishery products. However, the occurrence of viral diseases continues to be a significant limiting factor and its control is important for the development of this sector. In aquaculture farms, fish are reared under intensive culture conditions, and the use of viral vaccines has enabled an increase in production. Several types of vaccines and strategies of vaccination have been developed; however, this approach has not reached the expected goals in the most susceptible stage (fingerlings). Currently, there are inactivated and recombinant commercial vaccines, mainly for salmonids and cyprinids. In addition, updated genomic and proteomic technology has expedited the research and expansion of new vaccine models, such as those comprised of subunits or DNA. The objective of this review is to cover the various types of viral vaccines that have been developed and are available for bony fishes, as well as the advantages and challenges that DNA vaccines present for massive administration in a growing aquaculture, possible risks for the environment, the controversy regarding genetically modified organisms and possible acceptance by consumers.

Avibacterium paragallinarum is the causative agent of infectious coryza, an acute respiratory disease of chickens. In this study, a total of 28 isolates of A. paragallinarum from Ecuador were serotyped by the hemagglutinin scheme which recognizes nine serovars. Out of 28 isolates, 17 isolates belonged to serovar A-3, and five isolates to each serovars B-1 and C-1, whereas one isolate was non-typeable. This is the first report of A. paragallinarum serovar A-3 outside Brazil and serovar C-1 outside Japan.

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.