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Avian metapneumovirus (aMPV) is a highly contagious pathogen for broilers. Its epidemiological aspects remain poorly understood in Morocco. Given that, we carried out a pilot seroepidemiological survey from December 2020 to June 2021 to define aMPV seroprevalence in Moroccan broiler flocks in different bioclimatic zones (humid to sub-humid, semi-arid, arid) during winter and spring. According to these zones, 48 flocks not vaccinated against aMPV were selected using a stratified random sampling model. With a simple random sampling strategy, fifteen to thirty sera per flock were collected then analysed using a commercial indirect ELISA kit (CIVTEST AVI TRT®, HIPRA S.A., Amer, Spain) that was able to titre antibodies against aMPV subtypes A and B. Furthermore, questionnaires were shared with veterinarians in charge of flocks to collect data and analyse it with multivariable logistic regression models to identify risk factors associated with virus circulation. From 1142 sera, 912 tested positive with the ELISA used, showing an overall aMPV seroprevalence of 79.86% in the broilers. The arid zone had the highest seroprevalences: 94.16% during winter and 84.82% during spring. Bioclimate and season seemed to contribute to aMPV seropositivity. Likewise, high stocking densities and poor hygiene scores on farms were proven to predispose birds to seropositivity. Hereby, we show the circulation of aMPV in Moroccan broiler farms is influenced by bioclimate, season, density, and hygiene conditions. The present study is the first serological evidence of aMPV in broilers in the Maghreb region.

Avian Metapneumovirus infection first emerged in South African turkeys, followed by respiratory problems in chickens with a swollen head syndrome. The etiological agent is a Metapneumovirus in the Pneumoviridae family and the first pneumovirus identified in avian species. This virus causes respiratory and reproductive affections that are worsened in the presence of other pathogens. The present review summarized the current knowledge about the virus's properties and spread, its different subtypes, and the immunological and pathological mechanisms, especially in the broilers. The diagnostic methods are based on serology and essentially ELISA to show and titer antibodies following infection in naïve birds. Molecular tools such as PCR aim to detect and subtype avian Metapneumovirus genetic material. Besides biosecurity, prevention relies mostly on good management and vaccination. [ABSTRACT FROM AUTHOR]