Animal origin likely
Because most patients stated in a questionnaire that they had been exposed to an animal during the month preceding the onset of their symptoms, the researchers tested goats, dogs, pigs, and cattle living in the villages of infected patients for antibodies against LayV. They found LayV antibodies in a handful of goats and dogs and identified LayV viral RNA in 27% of the 262 sampled shrews. These findings suggest that the shrew may be a natural reservoir of LayV, passing it between themselves “and somehow infecting people here and there by chance,” Emily Gurley, PhD, MPH, an infectious diseases epidemiologist at Johns Hopkins University, Baltimore, told Nature.
The researchers did not find strong evidence of LayV spreading between the people included in the study. There were no clusters of cases in the same family, within a short time span, or in close geographical proximity. “Of the 35 cases, not a single one is linked,” said Dr. Wang, which Dr. Gurley considered good news. It should be noted, however ,”that the study did retrospective contact tracing on only 15 family members of nine infected individuals, which makes it difficult to determine how exactly the individuals were exposed,” reported Nature.
Vigilance is needed
Should we be worried about a potential new epidemic? The replies from two experts interviewed by Nature were reassuring. “There is no particular need to worry about this virus, but ongoing surveillance is critical,” said Professor Edward Holmes, an evolutionary virologist at the University of Sydney. Regularly testing people and animals for emerging viruses is important to understand the risk for zoonotic diseases – those that can be transmitted from other animals to humans, he said.
It is still not clear how people were infected in the first place – whether directly from shrews or an intermediate animal, said Dr. Gurley. That’s why a lot of research still needs to be done to work out how the virus is spreading in shrews and how people are getting infected, she added.
Nevertheless, Dr. Gurley finds that large outbreaks of infectious diseases typically take off after a lot of false starts. “If we are actively looking for those sparks, then we are in a much better position to stop or to find something early.” Still, she noted that she didn’t see anything in the data to “cause alarm from a pandemic-threat perspective.”
Though there is not currently any cause for worry of a new pandemic, vigilance is crucial. Professor Holmes says there is an urgent need for a global surveillance system to detect virus spillovers and rapidly communicate those results to avoid more pandemics, such as the one sparked by COVID-19. “These sorts of zoonotic spillover events happen all the time,” he said. “The world needs to wake up.”
This article was translated from the Medscape French edition. A version appeared on Medscape.com.