Viruses constantly emerge and evolve, with some posing significant threats to human and animal health, while others remain confined to specific species. A recently identified example of the latter is the Camp Hill Virus (CHV), named after its discovery site in Camp Hill, Alabama.
The virus was isolated from the northern short-tailed shrew, a small mammal. CHV was found to be related to henipaviruses, a group known for their potential to cause severe disease in humans and animals.
“It is similar to other henipaviruses found in Asia, Australia, Europe, and parts of Africa,” said J. Victor Garcia-Martinez, Ph.D., professor and Charles H. McCauley Endowed Chair in the UAB Department of Microbiology, “which are known to cause severe respiratory illnesses and encephalitis.”
However, researchers have not observed CHV crossing species barriers or infecting humans.
“It is most closely related to other henipaviruses found in shrew species, none of which have been detected in humans,” explained Nicholas Lennemann, Ph.D., assistant professor in the UAB Department of Microbiology.
According to Angela Wahl, Ph.D., associate professor in the UAB Department of Microbiology and Todd Green, Ph.D., associate professor in the UAB Department of Microbiology, CHV is a negative-sense RNA virus that shares about 75 percent genetic similarity with Ninorex virus, previously found in Europe.
Garcia-Martinez, Lenneman, Wahl, and Green, offer additional insights into the virus, highlighting its potential risks and the need for continued research and surveillance.
Transmission and potential contagion
The Camp Hill virus was detected in the kidneys of all four shrews tested, though no symptoms were observed in the infected animals.
“So far, there is no evidence of human infection with Camp Hill virus,” Wahl said. “Other henipaviruses that transmit to humans typically do so through contact with infected animals or their bodily fluids. Nipah virus, which can spread between humans, is transmitted through direct contact with bodily fluids and respiratory secretions.”
While other henipaviruses have been known to infect humans, current research suggests that CHV remains restricted to its shrew host.
“The mode of transmission for CHV has not been determined,” Lennemann explained. “However, its presence in the kidneys suggests it could spread through aerosolized rodent urine, as seen in some hantaviruses. That said, there is no evidence to suggest CHV is capable of infecting humans—it has not been found in humans.”
Severity and symptoms
According to Wahl, the symptoms associated with infection in shrews remain unknown.
When comparing CHV to other high-mortality viruses, Wahl explained, "The virus is similar to Nipah virus and Hendra virus—both henipaviruses that have been transmitted to humans and can cause up to 70 percent mortality. However, what makes Camp Hill virus different is that it appears to primarily target kidney cells in shrews."
Public health response
While efforts are being made to combat emerging henipaviruses, further research is necessary to determine whether CHV poses a risk to humans.
“There are several groups in the U.S. working on developing vaccines against emerging henipaviruses that have been shown to infect humans,” Lennemann explained. “However, additional studies on CHV would be required to warrant the development of specific interventions in humans for this virus.”
Currently, no specific treatments exist for henipaviruses, though ongoing research may provide potential options.
“There are no specific antivirals or vaccines for henipaviruses at this time,” Wahl said. “However, studies are underway to evaluate antivirals for the Nipah virus, which is related to the Camp Hill virus. Some of these antivirals could also be tested for efficacy against the Camp Hill virus.”
Green added, "A Hendra virus vaccine is available for horses, aimed at reducing transmission from horses to humans, but no vaccine currently exists for human use.”
Risk assessment
According to Wahl, the populations most at risk are “those who frequently come into contact with wild animals, especially in areas of Alabama where northern short-tailed shrews are found.”
To reduce the risk of exposure, Wahl advises the public to exercise caution when interacting with wildlife. “People should always take precautions when encountering animals in the wild, particularly species like shrews that could carry potentially harmful viruses.”
Lennemann further emphasized the importance of observing wild animals from a safe distance.
“As with all wild animals, it’s best to observe them from a distance,” he said. “Although CHV hasn’t been shown to infect humans, the possibility of viruses crossing species barriers should still be considered.”
He also noted, “This study highlights a need for virus surveillance in rural and urban populations in order to identify and understand the potential for emergence of highly pathogenic viruses into the human population.”
Garcia-Martinez added, “The discovery of Camp Hill virus in the U.S. underscores the importance of continuous surveillance and research to assess the potential impact of emerging and re-emerging infectious diseases on human health, something UAB remains committed to through its ongoing research efforts.”
Green cautioned that CHV was not the only virus detected in shrews, saying, “A study on CHV also identified Camp Ripley virus, a hantavirus, in the same shrews, indicating a co-infection. This species has also been documented as a reservoir for Powassan virus, an Orthoflavivirus that can cause encephalitis or meningitis, leading to long-term complications in up to 50% of patients and a 15% fatality rate.”