Among the respiratory pathogens of birds, the Avian Metapneumovirus (aMPV) is one of the most relevant, as it is responsible for causing infections of the upper respiratory tract and may induce respiratory syndromes. aMPV is capable of affecting the reproductive system of birds, directly impacting shell quality and decreasing egg production. Consequently, this infection can cause disorders related to animal welfare and zootechnical losses. The first cases of respiratory syndromes caused by aMPV were described in the 1970s, and today six subtypes (A, B, C, D, and two more new subtypes) have been identified and are widespread in all chicken and turkey-producing countries in the world, causing enormous economic losses for the poultry industry. Conventionally, immunological techniques are used to demonstrate aMPV infection in poultry, however, the identification of aMPV through molecular techniques helped in establishing the traceability of the virus. This review compiles data on the main aMPV subtypes present in different countries; aMPV and bacteria co-infection; vaccination against aMPV and viral selective pressure, highlighting the strategies used to prevent and control respiratory disease; and addresses tools for viral diagnosis and virus genome studies aiming at improving and streamlining pathogen detection and corroborating the development of new vaccines that can effectively protect herds, preventing viral escapes.

Brazil is the second largest producer of broiler chicken in the world, and the surveillance of avian pathogens is of great importance for the global economy and nutrition. Avian metapneumovirus (aMPV) infection results in high rates of animal carcass losses due to aerosacculitis and these impacts can be worsened through co-infection with pathogenic bacteria, particularly Escherichia coli (APEC). The present study evaluated the seroprevalence of the main aMPV subtypes in unvaccinated broiler chickens from poultry farms in Brazil, as well as the clinical effects of co-infection with APEC. Blood samples, respiratory swabs, femurs, liver, and spleen of post-mortem broiler chickens were collected from 100 poultry production batches, totaling 1000 samples. The selection of the production batch was based on the history of systemic and respiratory clinical signs. The results indicated that 20% of the lots showed serological evidence of the presence of aMPV, with two lots being positive for aMPV-B. A total of 45% of batches demonstrated co-infection between aMPV and APEC. The results point to the need for viral surveillance, targeted vaccination, and vaccination programs, which could reduce clinical problems and consequently reduce the use of antibiotics to treat bacterial co-infections.

Colibacillosis is a disease caused by Escherichia coli and remains a major concern in poultry production, as it leads to significant economic losses due to carcass condemnation and clinical symptoms. The development of antimicrobial resistance is a growing problem of worldwide concern. Lysogenic bacteriophages are effective vectors for acquiring and disseminating antibiotic resistance genes (ARGs). The aim of this study was to investigate the complete genome of Escherichia coli isolates from the femurs of Brazilian broiler chickens in order to investigate the presence of antimicrobial resistance genes associated with bacteriophages. Samples were collected between August and November 2021 from broiler batches from six Brazilian states. Through whole genome sequencing (WGS), data obtained were analyzed for the presence of antimicrobial resistance genes. Antimicrobial resistance genes against the aminoglycosides class were detected in 79.36% of the isolates; 74.6% had predicted sulfonamides resistance genes, 63.49% had predicted resistance genes against β-lactams, and 49.2% of the isolates had at least one of the tetracycline resistance genes. Among the detected genes, 27 have been described in previous studies and associated with bacteriophages. The findings of this study highlight the role of bacteriophages in the dissemination of ARGs in the poultry industry.

Infectious bronchitis virus (IBV) poses a significant threat to poultry worldwide, necessitating robust surveillance and vaccination strategies. This study aimed to conduct IBV surveillance in Brazil, assess potential vaccine viral escapes, and evaluate vaccine persistence in vaccinated broilers. A total of 1000 tracheal swabs from 100 flocks across six states were analyzed using RT-PCR. The results showed that 91% of the flocks tested positive for IBV. The detected strains included GI-1, GI-11, and GI-23. Notably, 90% of batches received vaccines containing either GI-1 or GI-11 lineages. The study revealed vaccine persistence in 67 samples between days 16 and 32 post-vaccination. In contrast, unvaccinated batches had a high prevalence of IBV GI-11 strains (70%). These findings highlight widespread IBV circulation in Brazil with persistent viral presence in vaccinated birds and wild viruses in unvaccinated ones. Collectively, the data reveal a widespread presence of IBV in Brazil, characterized by prolonged viral persistence in vaccinated animals and the occurrence of wild viruses in both unvaccinated birds and those vaccinated against specific strains. It can be concluded from this study that there was a widespread occurrence of IBV in Brazil, providing long viral persistence in vaccinated animals, as well as the occurrence of wild virus in unvaccinated birds or birds vaccinated against individual strains.

Avian pathogenic Escherichia coli (APEC) causes colibacillosis, one of the main diseases leading to economic losses in industrial poultry farming due to high morbidity and mortality and its role in the condemnation of chicken carcasses. This study aimed to isolate and characterize APEC obtained from necropsied chickens on Brazilian poultry farms. Samples from birds already necropsied by routine inspection were collected from 100 batches of broiler chickens from six Brazilian states between August and November 2021. Three femurs were collected per batch, and characteristic E. coli colonies were isolated on MacConkey agar and characterized by qualitative PCR for minimal predictive APEC genes, antimicrobial susceptibility testing, and whole genome sequencing to identify species, serogroups, virulence genes, and resistance genes. Phenotypic resistance indices revealed significant resistance to several antibiotics from different antimicrobial classes. The isolates harbored virulence genes linked to APEC pathogenicity, including adhesion, iron acquisition, serum resistance, and toxins. Aminoglycoside resistance genes were detected in 79.36% of isolates, 74.6% had sulfonamide resistance genes, 63.49% showed β-lactam resistance genes, and 49.2% possessed at least one tetracycline resistance gene. This study found a 58% prevalence of avian pathogenic E. coli in Brazilian poultry, with strains showing notable antimicrobial resistance to commonly used antibiotics.

Os vírus entéricos são vírus não envelopados que se replicam no trato gastrointestinal e apresentam transmissão fecal-oral. Estão, portanto, associados às más condições de saneamento básico e controles sanitários. As infecções por vírus entéricos podem causar enfermidades em indivíduos susceptíveis, principalmente crianças com idade inferior aos dez anos. Estas enfermidades estão associadas ao consumo de água e alimentos contaminados devido ao descarte inadequado de esgotos e águas residuais. A legislação brasileira não inclui a análise de vírus entéricos para determinar a qualidade da água, apenas padrões bacterianos, recomendando a análise de vírus apenas em caso de surtos de veiculação hídrica. Os vírus entéricos, por terem característica proteica e serem não-envelopados permanecem com capacidade infecciosa no ambiente, mesmo em contato com cloro, salinidade e aumentos de temperatura. Neste sentido, o presente capítulo apresenta uma introdução aos vírus entéricos, destacando sua presença em águas, alimentos e em efluentes de humanos e animais, considerando a necessidade do seu monitoramento para fins de segurança sanitária.