#18,232
While it doesn't get a lot of attention, the diminutive shrew - a tiny mole-like creature which can be found across much of the globe - with nearly 400 known species, is the 4th most species diverse mammal family, following two families of rodents and bats.
The initial report indicated - in addition to the confirmed human infections - that genetic testing of 25 animals found low levels of the virus in dogs (5%) and goats (2%), but much higher levels (27%) in shrews, which they suspect may be the reservoir host for this virus.Two years ago, Chinese scientists reported on an outbreak of a previous unknown henipavirus virus among farmers (see NEJM: A Novel Henipavirus With Human Spillover In China).
Six weeks later, in J. Virus Erad: A Review Of The Langya Virus Outbreak in China, 2022, we looked at a more detailed review of this emerging virus, where the authors wrote:
Langya virus is a zoonotic virus that belongs to the family Paramyxoviridae; genus Henipavirus with close relation to species; HeV and NiV. Its animal reservoir is shrews, others being domestic goats and dogs. Its symptoms can range from mild respiratory illness to fatal encephalitis.
Since then, shrews have come under increased scrutiny as potential carriers of zoonotic diseases. A few recent studies include:
Molecular prevalence, subtype distribution, and zoonotic potential of Blastocystis sp. in wild rodents and shrews inhabiting Zhejiang province of ChinaMpox infection in animals: A systematic review and meta-analysis
To this growing list we can add a fascinating report, published this week in Nature, which finds a remarkably diverse range of pathogens (including influenza H5N6) in Shrews captured along the East Coast of China.
This is a lengthy, and highly detailed report, which needs to be read in its entirety to fully appreciate its findings. I've only posted the link, abstract, and a couple of excerpts below. Follow the link to read it in its entirety.
I'll have a bit more after the break.
Decoding the RNA viromes in shrew lungs along the eastern coast of ChinaJing-Tao Zhang, Zhen-Yu Hu, Fang Tang, Yan-Tao Liu, Wei-Long Tan, Xiao-Fang Ma, Yun-Fa Zhang, Guang-Qian Si,Lei Zhang, Mei-Qi Zhang, Cong Peng, Bo-Kang Fu, Li-Qun Fang, Xiao-Ai Zhang & Wei Liu
npj Biofilms and Microbiomes volume 10, Article number: 68 (2024) Cite this article
Abstract
Shrews being insectivores, serve as natural reservoirs for a wide array of zoonotic viruses, including the recently discovered Langya henipavirus (LayV) in China in 2018. It is crucial to understand the shrew-associated virome, viral diversity, and new viruses.
In the current study, we conducted high-throughput sequencing on lung samples obtained from 398 shrews captured along the eastern coast of China, and characterized the high-depth virome of 6 common shrew species (Anourosorex squamipes, Crocidura lasiura, Crocidura shantungensis, Crocidura tanakae, Sorex caecutiens, and Suncus murinus).
Our analysis revealed numerous shrew-associated viruses comprising 54 known viruses and 72 new viruses that significantly enhance our understanding of mammalian viruses. Notably, 34 identified viruses possess spillover-risk potential and six were human pathogenic viruses: LayV, influenza A virus (H5N6), rotavirus A, rabies virus, avian paramyxovirus 1, and rat hepatitis E virus.
Moreover, ten previously unreported viruses in China were discovered, six among them have spillover-risk potential. Additionally, all 54 known viruses and 12 new viruses had the ability to cross species boundaries. Our data underscore the diversity of shrew-associated viruses and provide a foundation for further studies into tracing and predicting emerging infectious diseases originated from shrews.
(SNIP)
Based on the analysis of RdRp protein sequences from RNA viruses and replicase protein sequences from DNA viruses, a total of 126 viruses from 23 families were identified and characterized (Fig. 2a and Supplementary Table 3–4).
This encompassed 35 species of positive-sense single-stranded RNA (ssRNA) viruses from nine families (Arteriviridae, Astroviridae, Dicistroviridae, Flaviviridae, Hepeviridae, Iflaviridae, Permutotetraviridae, Picornaviridae, and Solinviviridae); 23 negative-sense ssRNA viruses from ten families (Aliusviridae, Artoviridae, Chuviridae, Hantaviridae, Lispiviridae, Nairoviridae, Orthomyxoviridae, Paramyxoviridae, Rhabdoviridae, and Xinmoviridae); six double-stranded RNA (dsRNA) viruses from two families (Picobirnaviridae and Sedoreoviridae); as well as one single-stranded DNA (ssDNA) virus in the family Circoviridae and one reverse transcribing DNA (RTDNA) virus in the family Hepadnaviridae.
Additionally, there were 60 species of unclassified RNA viruses. Among these viral families, Paramyxoviridae was most frequently detected with the largest number of libraries (24), followed by Picobirnaviridae (14), Picornaviridae (13), Arteriviridae (12), and Orthomyxoviridae (11), whereas other viral families were only sporadically detected (Fig. 2a). No viruses closely related to either SARS-CoV, SARS-CoV-2 or other sarbecoviruses was found among all examined shrews.
While this study confines itself to shrews, we've seen other studies looking at a wider range of peridomestic mammals which have returned similar findings:
- A report from late 2023 ( V. Sinica: Diversity and Independent Evolutionary Profiling of Rodent-borne Viruses in Hainan, China) published by Chinese scientists that describes the discovery of 8 previously unknown pathogens with zoonotic potential circulating in rodents on Hainan Island, China.
- Last February, in Preprint: Virome Characterization of Field-Collected Rodents in Suburban Beijing, researchers identified 75 novel viruses and 67 known viruses from from 432 wild rodents tested; 25 viruses were classified as high-risk, including 8 zoonotic viruses and 17 spillover-risk viruses.
- Also in February, in Alaska Health Department Announces A Fatal Alaskapox Infection, public health officials identified red-backed voles and shrews as common carriers of the virus.
We can go back even further, to 2015's Taking HPAI To The Bank (Vole) which found this European mammal was susceptible to two types of avian flu viruses (H5N1 & H7N1), most were able to carry the virus asymptomatically, shed the virus in copious amounts, and were able to pass on the virus to naïve co-housed sentinel voles.
In 2013's mBio: A Strategy To Estimate The Number Of Undiscovered Viruses researchers from Columbia University's Mailman School of Public Health, EcoHealth Alliance, the NIH, et al. estimated a `. . . minimum of 320,000 mammalian viruses awaiting discovery.'All of which should give us pause when we see reports of HPAI H5N1 spillover into peridomestic mammals in and around infected farms (see USDA Adds 3 New Species (Deer Mice - Prairie Vole - Desert Cottontail) to Mammals with H5N1 List).
Thankfully, the vast majority won't have any appreciable impact on human health.
But the reality is, it only takes one `Spanish Flu', or `COVID' virus to claim millions of lives and to disrupt the entire globe for years to come.
