Unveiling the diversity, transmission, and zoonotic potential of microbes in true insectivores

Abstract The Eulipotyphla (true insectivores) is the third largest mammalian order, comprising over 500 species, and could be an important source of human infectious diseases. However, relatively little is known about the diversity of microbes in insectivores and the contribution of insectivores to virus transmission more specifically among wild hosts. In this study, we compiled a comprehensive dataset containing over 400,000 records of insectivores and their associated microbes from 1903 to 2023. Our analyses showed that insectivores host a wide spectrum of 941 microbes, 60% of which are viruses and are predominantly found in the shrew and hedgehog families. Notably, human-associated viruses harbored by shrews and hedgehogs were phylogenetically closely related to those found in humans, suggesting potential bidirectional transmission between insectivores and humans. Moreover, virus-sharing networks revealed that insectivores held the second-most central position for virus sharing, just second to bats, among all mammalian orders. Insectivores had a high proportion of cross-order transmitted viruses, including many human-associated viruses. Dietary diversity, habitat diversity, and distributional traits (e.g. geographical range size, mean latitude, and urban adaptation status) emerged as the key ecological factors contributing to this cross-species virus transmission. Our findings highlight the microbial diversity present in insectivores, indicating this order may act as potential incubators for novel viruses capable of infecting mammals and spreading viruses of public health concern.