Viruses (Including SARS-CoV-2), Nematodes and Their Spread

This review explores a hypothetical and previously underexplored ecological pathway that may contribute to virus dispersal, including human pathogens, through passive transport involving free-living nematodes and migratory animals. Available data on nematode-associated viruses, nematode survival in diverse environments, and mechanisms of passive dispersal are synthesized to propose a conceptual framework for long-distance pathogen movement. Particular attention is given to the ecological interactions among nematodes, animals, and viruses, and to the potential role of these interactions in shaping pathogen distribution patterns under environmental and anthropogenic pressures. The article discusses a theoretical model of possible virus transfer across ecological niches and highlights key gaps requiring experimental validation. This study highlights a previously underestimated route of potential virus transmission, including human pathogens, through possible long-distance dispersal (500 km or more) by free-living nematodes and migratory birds. Data on the spread of viruses of nematodes of the genus Caenorhabditis spp., the survival of nematodes in various conditions, and their spread by various groups of animal carriers, including their ability to pass through the gastrointestinal tract of birds in a viable state, are analyzed. The role of a number of migratory bird species as biological carriers not only of free-living nematodes themselves over considerable distances, but also of viruses hypothetically associated with nematodes on/inside their bodies, is considered as a potential mechanism. This work raises questions about previously underestimated biological risk factors associated with this potential route of passive pathogen dispersal to new territories and ecological niches, especially in conditions of environmental stress, intensive animal husbandry, and global movement of wild animals. The article discusses a hypothetical scenario in which SARS-CoV-2 and other viruses could be passively dispersed through ecological interactions involving nematodes and migratory birds. Understanding the ecological dynamics of the interaction between birds, nematodes, and virusesmay contribute to ecological risk assessment and understanding of emerging pathogen dynamics. This manuscript presents a conceptual ecological hypothesis and should not be interpreted as evidence of confirmed transmission pathways.