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Avian influenza is one of the most devastating avian diseases. The current high pathogenicity avian influenza (HPAI) A virus H5N1 clade 2.3.4.4b epizootic began in the 2020–2021 season, and has caused a panzootic, considered one of the worst ever reported. The present panzootic has novel epidemiological features that represent a challenge for its prevention and control. This review examines key epidemiological changes of the disease such as seasonality, geographic spread, and host range. The seasonality of the virus has changed, and contrary to previous avian influenza epizootics, this subclade was able to persist during boreal summer. Its geographic range has expanded, with reports in all continents except Australia. During this epizootic, HPAIV H5N1 has broadened its host range, infecting hundreds of bird species, and causing the death of thousands of wild birds and over 300 million poultry. The number and diversity of mammal species infected by H5N1 2.3.4.4b is unprecedented. Although considered low, this strain's potential to spillover to humans should not be underestimated, especially considering the current extremely high viral circulation in animals and increasing adaptation to mammals. Overall, HPAI A(H5N1) clade 2.3.4.4b represents an ongoing and growing threat to poultry, wildlife, and human health. [ABSTRACT FROM AUTHOR]

The knowledge regarding infectious agents affecting wildlife is crucial for species' conservation. We hypothesized that herpesviruses are present in wild Neotropical carnivores. Herein, we used DNA polymerase and glycoprotein B broad‐spectrum PCRs to molecularly survey the presence of herpesviruses in spleen and/or lung samples of 53 wild Neotropical carnivores of Brazil, comprising the families Canidae, Felidae, Mustelidae, and Procyonidae. The percentage of PCR‐positives was 28.3% (15/53). An alphaherpesvirus was found in a Neotropical river otter (Lontra longicaudis, 1/1), a betaherpesvirus in a lesser grison (Galictis cuja, 1/3), and different gammaherpesviruses in Neotropical river otter (1/1), lesser grison (1/3), crab‐eating raccoons (Procyon cancrivorus, 8/9), South American coati (Nasua nasua, 1/2), southern tiger cat (Leopardus guttulus, 1/2), jaguarundi (Puma yagouaroundi, 1/5), and ocelot (Leopardus pardalis, 1/10). None of the tested canids were herpesvirus‐positive. This is the first report of herpesvirus in procyonids, and in jaguarundi, southern tiger cat, lesser grison, and Neotropical river otter. This study broadens the host range of herpesviruses in Neotropical carnivores. [ABSTRACT FROM AUTHOR]

The European mink (Mustela lutreola) is a riparian mustelid, considered one of the most endangered carnivores in the world. Alpha, beta and gammaherpesviruses described in mustelids have been occasionally associated with different pathological processes. However, there is no information about the herpesviruses species infecting European minks. In this study, 141 samples of swabs (oral, conjunctival, anal), faeces and tissues from 23 animals were analysed for herpesvirus (HV) using a pan‐HV‐PCR assay. Two different, potentially novel, gammaherpesvirus species were identified in 12 samples from four animals (17.3%), and tentatively named Mustelid gammaherpesvirus‐2 (MUGHV‐2) and MuGHV‐3. Gross examination was performed on dead minks (n = 11), while histopathology was performed using available samples from HV‐positive individuals (n = 2), identifying several neoplasms, including B‐cell lymphoma (identified by immunohistochemistry) with intralesional syncytia and intranuclear inclusion bodies characteristic of HV (n = 1), pulmonary adenocarcinoma (n = 1), and biliary (n = 1) and preputial (n = 1) cystadenomas, as well as other lesions (e.g., axonal vacuolar degeneration [n = 2] and neuritis [n = 1]). Viral particles, consistent with HVs, were observed by electron microscopy in the mink with neural lymphoma and inclusion bodies. This is the first description of neoplasms and concurrent gammaherpesvirus infection in European minks. The pathological, ultrastructural and PCR findings (MuGHV‐2) in the European mink with lymphoma strongly suggest a potential role for this novel gammaherpesvirus in its pathogenesis, as it has been reported in other HV‐infected species with lymphoma. The occurrence of neural lymphoma with intralesional syncytia and herpesviral inclusions is, however, unique among mammals. Further research is warranted to elucidate the potential oncogenic properties of gammaherpesviruses in European mink and their epidemiology in the wild population. [ABSTRACT FROM AUTHOR]