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Covid in the sewers
Science In Action
Mar 17, 2022

Analysis of wastewater from sewage systems has provided an early warning system for the presence of Covid-19 in communities – showing up in the water samples before people test positive. It’s also possible to identify the variants and even specific genetic mutations. Davida Smyth of Texas A&M University has been using this technique in New York and found intriguing results - forms of the virus not present in humans. The suggestion is that mutated forms may be infecting other animals, possibly those present in the sewers.

An analysis of long Covid, symptoms of fatigue, and ‘brain fog’ which occur long after initial infection, show that around a quarter of those infected develop these symptoms. Lucy Cheke of Cambridge University discusses the implications.

The war in Ukraine has highlighted the importance of the region in supplying raw materials and energy to other countries, gas, cereal crops, and fertilisers in particular. As crop scientist John Hammond from Reading University explains, the stopping of fertiliser exports from Russia, in particular, could impact food security in many countries.

And with unseasonal fires already burning in the Western US Caroline Juang of Columbia University’s Earth Observatory gives us her analysis of the driving factors in the intensification of fires year-on-year.

(Image: USA, New York, steam coming out from sewer. Credit: Westend61/Getty Images)

Presenter: Roland Pease Producer: Julian Siddle

More Episodes
May 29, 2025
Thirteen months to a chip off the moon

China is aiming to join the small club of nations who have successfully returned scientific samples of asteroids for analysis on earth, teaching us more about how our and potentially other solar systems formed. Tianwen-2 launched successfully this week, bound for an asteroid known as Kamo‘oalewa, which sits in a very strange orbit of both the earth and the sun, making it a “quasi-satellite”.

Last year, scientists including Patrick Michel of the Côte d'Azur Observatory in France, published an intriguing suggestion that Kamo‘oalewa might in fact not be a conventional asteroid, but instead be a small piece of our moon that was ejected when the Giordano Bruno crater formed. In a little over a year from now, we might find out if that is right.

Do you have to hold text at arm’s length to read properly? Qiang Zhang, professor of physics at the University of Science and Technology of China, whose team recently published their demonstration of using a technique from radio astronomy but using optical light. Active Optical Interferometry involves using laser beams to achieve resolutions at distances far in excess of conventional imaging with lenses. As his team showed, and as Miles Paggett of Glasgow University admires, they managed to read newsprint sized letters at a distance of over 1.3km.

Finally, how did the Inca Empire write things down, and who did the writing? It has been thought that ornate threads of strings and baubles known as khipu are how records were made for business and administration, probably by a decimal code of knots in strings. But the exact purpose, nature and any meaning encoded therein, has eluded scholars for decades. Sabine Hyland, an anthropologist at the University of St Andrews, Scotland, has been studying them for years, and recently was granted access to the records of a village, only the fourth known, to have continued a form of the khipu tradition after the Spanish conquest to this day. She believes that they could even provide us in the modern world with valuable climate data.

Presenter: Roland Pease Producer: Alex Mansfield Production co-ordinator: Jazz George

(A Long March-3B Y110 carrier rocket carrying China's Tianwen-2 probe blasts off from the Xichang Satellite Launch Center on 29 May, 2025 in Sichuan Province of China. Credit: VCG/Getty Images)


35min 53sec

May 22, 2025
WHO Pandemic Agreement reached

This week, 124 countries agreed at the World Health Assembly in Geneva on measures aimed at preventing a future pandemic. The agreement very strongly favours a “One Health” approach, appreciating how so many potential pathogens originate in human-animal interactions. Still to agree on the terms of how to share pathogens and information with global science and vaccine researchers, eventually the treaty will need to be signed by at least 60 countries. But can the inequity between countries of the global south and north, and issues of intellectual property, be bridged?

A new study on origins of the Nigerian mpox epidemic points strongly to zoonotic crossovers and mobility of wildlife in West Africa. Edyth Parker of Redeemer’s University in Nigeria describes their phylogenetic tree.

Can the bovine form of H5N1 flu infect pigs, and could domestic pig populations then provide a crucible for further variants to develop? Jürgen Richt of Kansas State University and colleagues have been investigating. We need to keep up vigilance.

Lucy van Dorp of University College London, working with a consortium including London’s Crick Institute, has been looking at a moment in the past when human activity provided an opportunity for a bacterial human pathogen to change its lifestyle. According to their phylogenetic tree, the bacterium Borrelia recurrentis (which causes louse-borne relapsing fever in humans) adapted and moved from ticks to human body lice around about the same time as humans started using woollen clothing.

And Susan Lieberman, VP for International Policy at the Wildlife Conservation Society, was in the trenches of the Pandemic Agreement negotiations, and shares some of her hopes for its success.

Image: World Health Assembly formally adopts by consensus world's first Pandemic Agreement, Geneva, Switzerland - 20 May 2025 Image Credit: Magali Girardin via EPA-EFE/Shutterstock

Presenter: Roland Pease Producer: Alex Mansfield


40min 18sec

May 15, 2025
Vaccinating rabies’ reservoir dogs

In 2015, the World Health Organisation set the goal of eradicating rabies deaths from dog-bites to “Zero by 2030”. A team at the University of Glasgow and colleagues in Tanzania have been assessing the efficacy of dog vaccination schemes for reducing the numbers of human infections over the last 20 years. As Prof Katie Hampson tells Science in Action, in rural areas especially, vaccinating dog populations does work, but you need to keep at it, and not leave patches untouched. It should be funded as a public health measure, rather than a veterinary issue.

Last weekend, the remains of a failed 1972 Soviet mission to Venus landed harmlessly somewhere back on earth. As the BBC’s Maddie Molloy explains, the fears were that the robust lander craft would survive re-entry into earth’s atmosphere as it was originally engineered to withstand the harsh pressures and chemistry of Venus.

How and why then would sketches be emerging of Chinese plans to launch a sample-return mission to Venus in the next decade? Science Journalist Andrew Jones describes some of the challenges they will face collecting droplets of the highly acidic atmosphere somewhere 60km above the surface and turning round to head back to earth.

Why? William Bains of Cardiff University is one of a growing number of scientists interested in exploring some of the more exotic possibilities for complex organic biology in the otherwise destructive sulphuric, hot, dense, low pH clouds they will find. Could a different sort of information-encoding molecular chemistry enable life, though not as we know it?

Presenter: Roland Pease Producer: Alex Mansfield Production Coordinator: Jasmine Cerys George and Josie Hardy

Photo: A domestic dog receives a rabies vaccine during a mass vaccination in Bunda, Tanzania, October 8, 2012. (Chris Sweda/Chicago Tribune/Tribune News Service via Getty Images)


38min 45sec


Covid in the sewers

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