Every June 21st sees a census of the world’s urban microbes. Depending on where you live, June 21st is either the summer or the winter solstice. For some, this is a moment of celebration, accompanied by strange rituals. And among the celebrants are members of the International Metagenomics and Metadesign of Subways and Urban Biomes Consortium (Metasub). If, in Bogotá, Doha, Kuala Lumpur, London, Minneapolis or any other of some 60 cities around the world, you see on that day someone furtively swabbing a ticket counter, handrail, turnstile or seat in your local underground-railway station, be not afraid. It is just one of Metasub’s volunteers gathering samples of the local microbes...

The Economist: A midsummer bug hunt