The most deadly viruses in the world may be quietly fermenting in fruit orchards—literally over your head? You got it. In a finding that is generating high-profile buzz throughout the international scientific community, scientists in China have discovered over 20 novel bat viruses, some of which have close relatives to Hendra and Nipah—diseases with skull-chilling mortality rates and a track record of crossing over from animals to humans.So what does this all mean to you, me, and the rest of the world? A new science study issued a warning to the global health community: scientists have found over 20 previously unknown viruses in Chinese Yunnan province bats. Two newly discovered henipaviruses closely related to the lethal Hendra and Nipah viruses are causing special concern because of their likely ability to cause human and animal disease. Health professionals caution that these discoveries have "critical implications" for global public health, highlighting an urgent need for increased surveillance and biosecurity protocols.The discovery, reported in the journal PLOS Pathogens, has been sending shockwaves across the world's scientific and medical circles, with scientists alerting that the newly discovered viruses may have "critical implications" for global public health.The Two Viruses That Have Experts Particularly on EdgeTwo of the 22 viruses identified were particularly concerning: henipaviruses—a class of viruses with a reputation for being lethal. These were discovered in fruit bats that inhabit the vicinity of orchards and human habitations, a configuration that duplicates earlier outbreaks of Hendra virus in Australia. Among the viruses discovered in the study is the closest-known relative of the Hendra and Nipah viruses, which carry mortality rates of 40% to 80% in humans and are responsible for causing severe respiratory disease and brain inflammation.What is more alarming is the transmission mode: both Hendra and Nipah viruses can also be transmitted via bat urine. In farming areas where bats scavenge in fruit farms, infected fruit can be used as a bridge for spillover into livestock—or humans."Academically, this is not a concern," replied Associate Professor Vinod Balasubramaniam, a virologist at Monash University's Malaysian campus. "This has practical implications, particularly for nations such as Australia where the ecology is shockingly similar."Why Bats Are A Matter of Concern?Bats have long been known to be the main hosts of viruses that are able to leap onto humans and animals, sometimes with catastrophic consequences. From Ebola to SARS, MERS, and most recently, the coronavirus causing COVID-19, bats are often suspected to be responsible for the appearance of new infectious diseases. Their own biology—long lifespan, social roosting habits, and strong immune systems—tends to make them perfect reservoirs for a vast range of viruses.The emphasis of the new study on the kidneys is important. While most research to date has focused on bat saliva, feces, or blood, the kidneys might be important in viral shedding, especially by way of urine. This is particularly important for henipaviruses, which have been found to be excreted in bat urine and can infect fruit or surfaces and cause spillover to humans and animals.The Henipavirus ThreatOf all the viruses that have been found, the two new henipaviruses in fruit bats are of most concern to researchers. One of them is now known to be the closest-known relative of the Hendra and Nipah viruses—both of which have caused fatal outbreaks among humans and animals.Hendra and Nipah viruses have the notorious reputation for high mortality rates, ranging from 40% to 80%. They induce severe brain inflammation (encephalitis) and respiratory illness, and can spread efficiently within populations of both humans and animals. In Australia alone, Hendra virus has caused 66 recorded outbreaks since 1994, killing four individuals and scores of horses. Nipah virus, on the other hand, has produced recurrent outbreaks in South and Southeast Asia, frequently associated with the consumption of fruit or fruit products contaminated by urine from bats.The detection of henipaviruses closely related to each other in Yunnan's fruit bats—particularly those that inhabit orchards and villages—heightens the possibility of future spillover incidents. As Associate Professor Vinod Balasubramaniam of the Malaysian campus of Monash University points out, "The proximity between the Australian rural setting and Yunnan's orchards close to human dwellings emphasizes the need for heightened surveillance and biosecurity efforts."How Do These Viruses Spread?Bats have come under closer scientific examination as natural reservoirs for most lethal viruses, including SARS, MERS, Ebola, and even SARS-CoV-2. This research is special because it targets the kidneys—a less often examined organ in virology studies.Both Hendra and Nipah viruses can be spread by contact with bat urine. Fruit bats in agricultural environments tend to roost and feed in orchards near human habitation. When their urine gets onto fruit, the virus is consumed by livestock or human beings, paving the way for possible outbreaks.This method of transmission is especially cause for alarm in areas where humans and animals are in close contact to bat habitats. As Dr. Alison Peel, a disease ecologist of wildlife at the University of Sydney, describes, these results indicate "potential opportunities for contact" with humans—particularly those in rural and peri-urban settings.This research broadens our knowledge of the bat kidney infectome," scientists said. "It identifies the imperative zoonotic dangers lurking in plain sight and emphasizes the importance of complete-spectrum viral monitoring in understudied organs.As per Dr. Yong Gao Peng, a virologist who participated in the research, "This finding does not mean an outbreak will be imminent. But it does show just how much we still don't know about the viral world within bats, and how important it is to chart it out comprehensively."Why the World Should Pay Attention?The detection of so many new bat viruses in a fairly small sample puts into perspective how much scientists actually still have yet to learn about the microbial universe borne by bats. As Dr. Yong Gao Peng, a virologist at Nias, cautions, "While the results are based on bat kidney samples and do not suggest impending outbreaks, they show how much we still don't know about the microbes bats carry."In light of the past history of lethal outbreaks with bat-borne viruses, the stakes are obvious. Increased monitoring, particularly where bats and humans coexist in close proximity, is called for. The research also underscores the necessity of thorough investigations of hitherto less-studied organs—such as the kidneys—to fully evaluate the entire range of spillover threats."These viruses don't have to be pathogenic today," added Dr. Peel, "because viruses change. The take-home message here is the need for urgency in surveillance, especially in ecotones where humans, animals, and wildlife overlap."Dr. Peng further contributes that the existence of such viruses, while localized to kidneys in this instance, is a sign from nature. "Most outbreaks are initiated by asymptomatic spillovers," he states. "Without timely detection and proper containment measures, they could quietly ferment into international crises."This finding arrives as the globe is still fighting COVID-19 and wrestling with the advent of new infectious variants. Only 6% of Australian adults have been vaccinated with the new COVID-19 booster, as reported in national health figures. With the northern hemisphere preparing to face another winter surge, public health officials say complacency is not a choice.