| Many countries now battling a resurgence of the coronavirus are learning that they were too late in discovering the virus was back. That's in part because the virus had already transmitted widely, and quietly, in the population before it made anyone visibly sick—a stealthy quality that's challenging containment efforts. Indeed, despite the re-introduction of social-distancing measures and lockdowns, it's still spreading unfettered in places like Melbourne. It's becoming more urgent to find a way to catch the virus's resurgence at an earlier stage, a task scientists around the world are now working on. One method is sewage surveillance—testing for traces of the virus in wastewater flushed down toilets. When people are infected with Sars-CoV-2 but haven't yet developed symptoms, they not only spread the virus through respiratory droplets, but also shed them in stool.  A laboratory in Paris monitors wastewater to detect the presence of the coronavirus. Photographer: THOMAS SAMSON/AFP Dutch scientists in March found that the detection of the coronavirus in sewage precedes an increase in clinical cases. Since then, similar studies of the pathogen's presence in wastewater conducted in the U.S. and Europe have backed that up. Countries like Singapore are now prying open the city's manholes to collect brownish liquid for virus testing. The hope is that such advance surveillance methods can help governments stay on top of resurgences while allowing residents to live mostly normal lives. There are other alternative surveillance methods being investigated. The ultra-sensitive sense of smell that dogs possess could be harnessed, with multiple teams across Europe and Australia now training hounds to sniff out metabolic changes in people infected with the virus. There are also "pandemic drones" being outfitted with sensors and vision systems to spot people with telltale signs of respiratory infections within crowds. To be sure, most of these alternative methods aim to seek out vestiges of the virus in places where it isn't apparent, making their relevance where the illness is widespread, such as in parts of the U.S. and some developing countries, questionable. They'll also likely face resistance from populations that prize privacy and individual choice, especially in the absence of detected cases. Still, with lockdowns showing signs of no longer working and a vaccine still at least months away, governments are quickly running out of options and these alternative methods could provide a lifeline.—Dong Lyu | 
⋗≗⋄〖Film!〗 2020 Rosas do Asfalto PelÃcula Completa En LÃnea released 2020. story: Rosas do Asfalto PelÃcula Completa En LÃnea. △∴∻Rosas do...
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