Emerging Viral Threats: Influenza D Virus and Canine Coronavirus HuPn-2018 Identified as High-Risk Candidates
A recent perspective review has identified Influenza D virus (IDV) and Canine Coronavirus HuPn-2018 (CCoV-HuPn-2018) as high-risk viral candidates with potential for human infection and epidemic spread. The review highlights that these viruses are not routinely detected by current diagnostic and surveillance systems, leading to calls for enhanced monitoring at the human-animal interface and the development of specific diagnostic tools and preventive measures.
Overview of Emerging Viral Threats
A perspective review published in Emerging Infectious Diseases consolidated data on the Influenza D virus (IDV) and Canine Coronavirus HuPn-2018 (CCoV-HuPn-2018), categorizing them as viruses of concern. Both have been identified in animal populations and show evidence of human exposure and potential infection, particularly in occupational groups with frequent animal contact.
These viruses belong to families (Orthomyxoviridae and Coronaviridae) that have historically produced respiratory pathogens capable of zoonotic transmission and widespread human outbreaks, such as H1N1 and SARS-CoV-2.
Influenza D Virus (IDV)
IDV was first identified in pigs with respiratory illness in 2011. Structurally, it is similar to Influenza C virus but possesses a broader host range, with cattle identified as a significant reservoir.
Research indicates human exposure, especially among those in close contact with livestock.
- Studies have shown over 97% of Florida cattle workers tested positive for neutralizing antibodies against IDV.
- 67% of dairy workers in Colorado showed molecular evidence of the virus in their noses over a five-day period, suggesting frequent infections that may be subclinical.
- Serological evidence of infection was also found in 73% of 612 participants in a study in China.
Laboratory experiments demonstrate IDV's capacity for airborne droplet transmission between ferrets and its efficient replication in human airway epithelial cells. Direct evidence of human-to-human transmission is currently unconfirmed.
Canine Coronavirus HuPn-2018 (CCoV-HuPn-2018)
This virus is a novel recombinant coronavirus, incorporating genetic material from both canine and feline coronaviruses. It was initially isolated in 2021 from a child hospitalized with pneumonia in Malaysia.
Since its initial detection, CCoV-HuPn-2018 has been identified in individuals with respiratory illness in several countries, including Haiti, Thailand, the USA, and Vietnam, suggesting a potentially broad geographic distribution. Surveillance studies in Vietnam detected the virus in 9% of patients hospitalized with pneumonia.
Evolutionary and cell-culture studies suggest the virus can infect human cells through pathways independent of the standard aminopeptidase N receptor.
Diagnostic and Surveillance Challenges
Current routine diagnostic tests and surveillance systems do not typically detect IDV or CCoV-HuPn-2018.
This lack of detection can lead to cases being misdiagnosed or classified as "pneumonia of unknown origin," particularly as standard clinical respiratory panels often miss CCoV-HuPn-2018. This situation suggests that these viruses may be unrecognized contributors to a subset of pneumonia cases.
Approved laboratory tests or vaccines are not yet available for these two viruses.
Recommendations for Enhanced Preparedness
The perspective review advocates for several measures to mitigate the potential public health risks posed by these viruses:
- Diagnostic Development: Immediate development of commercial real-time reverse transcription PCR (RT-PCR) tests specifically targeting IDV and CCoV-HuPn-2018.
- Enhanced Surveillance: A shift towards "panspecies" diagnostics and the strategic, targeted use of agnostic next-generation sequencing. This should be focused on high-risk human-animal interfaces, such as farms and markets.
- Clinical Awareness: Clinicians are advised to consider IDV and CCoV-HuPn-2018 when standard diagnostic panels do not identify a cause for pneumonia.
- Research & Development: Evaluation of antivirals and potential vaccines for these pathogens is also recommended.
- "One Health" Approach: Implementation of a "One Health" surveillance strategy at the human-animal interface to reduce the risk of future epidemics.
These recommendations underscore the importance of improved surveillance and preparedness to prevent future widespread outbreaks from novel respiratory viruses.