Global health risks back in focus as animal viruses emerge
Emerging viruses draw renewed concern
Two animal-origin viruses are drawing attention from infectious disease researchers who warn they could spread more widely among humans if gaps in monitoring persist. The viruses, influenza D virus (IDV) and canine coronavirus, have circulated for years with little public attention. Scientists now say current conditions favor broader transmission.
Related: Nipah Virus triggers health alerts in Asia
Warnings from public health experts
In a January article published in Emerging Infectious Diseases, a journal of the US Centers for Disease Control and Prevention, (CDC), a group of infectious disease experts cautioned that delayed surveillance and limited diagnostic testing raise the risk of outbreaks linked to these pathogens. According to the authors, both viruses show traits associated with respiratory illness in humans, yet public health responses remain limited.
John Lednicky, a research professor at the University of Florida (UF) College of Public Health and Health Professions, said their review of existing studies shows both viruses pose respiratory disease risks to people. He said that if either virus develops efficient person to person transmission, it could trigger epidemics or pandemics because most people lack immunity.
Influenza D virus and animal exposure
Influenza D virus (IDV) was first identified in 2011 and has been linked to infections in pigs and cattle. Researchers have since detected it in other animals, including poultry, deer, giraffes, and kangaroos. The virus contributes to bovine respiratory disease, which costs the American cattle industry an estimated one billion dollars each year.
Earlier studies by the research team examined cattle workers in Colorado and Florida. Results showed that up to 97 percent of workers carried antibodies to IDV, which points to prior exposure. These infections did not cause noticeable illness, but researchers say the virus shows signs of rapid genetic change. A strain isolated in China has already demonstrated the ability to spread between humans.
Lednicky said IDV has not caused severe illness in people so far. He added that canine coronavirus has caused human disease, but routine testing rarely includes it, leaving its broader impact unclear.
According to the CDC , IDV primarily affects cattle but can spill over to other animals. Meanwhile, studies show that infections have been confirmed worldwide through serological and molecular testing, as well as virus isolation. Researchers said that the virus carries a hemagglutinin-esterase fusion protein, which sets it apart from other influenza viruses and determines its broad host range. Cattle are considered the main reservoir, and the virus contributes to bovine respiratory disease syndrome. Animals associated with humans that can be infected include camels, pigs, small ruminants, and horses, while wild and captive species such as feral pigs, wild boars, deer, hedgehogs, giraffes, wildebeests, kangaroos, wallabies, and llamas have also tested positive. High antibody prevalence in camels suggests they may serve as a reservoir as well. Studies have detected IDV antibodies in people with professional contact with cattle, indicating potential zoonotic risk, though no cases of illness in the general population have been documented.
Canine coronavirus in humans
Canine coronavirus typically causes gastrointestinal illness in dogs and is different from the virus that causes Covid-19. While human cases remain uncommon, researchers have linked infections to pneumonia hospitalizations in parts of Southeast Asia.
In a study led by Lednicky, a UF team isolated a canine coronavirus from a medical worker who traveled from Florida to Haiti in 2017. The individual later developed mild fever and malaise. The researchers named the strain HuCCoV_Z19Haiti.
Evidence of global circulation
In 2021, a research group led by Gregory Gray at the University of Texas Medical Branch identified another strain, CCoV-HuPn-2018. Scientists isolated it from a hospitalized child in Malaysia. Genetic analysis showed the virus closely resembled the strain identified by the Florida team. Since then, researchers have detected CCoV-HuPn-2018 in people with respiratory illness in Thailand, Vietnam, and the U.S. state of Arkansas. These findings indicate the virus already circulates across multiple regions.
Lessons from past outbreaks
The researchers said recent findings involving IDV and canine coronavirus echo lessons from earlier pandemics. They said a virus that gains efficient human transmission can escalate quickly into a widespread outbreak. According to the authors, stronger virus monitoring, improved testing, medical treatments, and potential vaccines could reduce that risk. They added that current knowledge about how these viruses spread and cause disease remains limited. Even so, available evidence points to a serious public health concern.
New findings from China
Researchers in China have also reported growing concern about a livestock-linked influenza variant that shows signs of adaptation to humans. The findings add to broader scientific attention on IDV. A research team from the Changchun Veterinary Research Institute studied a strain known as D/HY11, first detected in livestock in northeastern China in 2023.
According to the study, the virus can grow and replicate in human airway cells and in several animal tissues, which suggests increasing adaptation to human biological conditions. The researchers found that the virus could spread through the air between animals such as rodents and ferrets without direct contact. Ferrets serve as a standard model for studying influenza transmission in humans, and the findings suggest possible future airborne transmission among people.
Blood tests showed that about 74% of people in northeastern China carried antibodies to the virus, which indicates widespread exposure. Among individuals with respiratory symptoms, the antibody rate reached 97%. The researchers said it remains unclear whether transmission has occurred between humans or if infections resulted from direct contact with animals.
The team concluded that IDV outbreaks have likely become an ongoing problem affecting both livestock and humans. They said the findings reinforce warnings that gaps in surveillance and testing could delay detection of viruses with broader public health implications.
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