Shamonda-like Virus in Europe: An Overlooked Nematode–Culicoides Transmission Pathway?

The recent emergence and rapid spread of Shamonda-like virus (SHAV/DE/2026) across several European countries raises questions about the mechanisms facilitating the circulation of this and related arboviruses. Although Culicoides biting midges are considered the most plausible vectors, the ecological pathways by which viruses may enter and persist within these insects remain incompletely understood. Here, we examine a potentially overlooked component of arbovirus transmission ecology: interactions among viruses, nematodes, and Culicoides. Published evidence demonstrates that mermithid nematodes can penetrate Culicoides larvae, develop within the insect, and in some systems persist through metamorphosis into adult midges. Importantly, experimental studies have also demonstrated nematode-associated enhancement of viral infection in Culicoides and virus carriage by nematodes in other arthropod systems. Based on these observations, we propose a testable environmental pathway in which virus-associated nematodes may facilitate viral entry into immature Culicoides, potentially linking environmental virus sources with adult vectors and susceptible vertebrate hosts. This hypothesis warrants targeted experimental investigation. If confirmed, such a pathway could expand current concepts of arbovirus transmission and should be considered in future biosurveillance, biorisk assessment, and preventive strategies against emerging arbovirus-associated biological threats.