If the world does not curb its greenhouse gas emissions, by the end of this century, the number of people dying annually because of extreme heat will be greater than the current global death toll from infectious diseases - that’s all infectiousness diseases, from malaria to diarrhoeal diseases to HIV. This is the grim assessment of climate researchers and economists of the Climate Impact Lab in the largest global study to date of health and financial impacts of temperature-related deaths. Roland Pease talks to Solomon Hsiang of the University of California, Berkeley.

UK ecologists have new insights about how diseases jump the species barrier from wildlife to humans. With a global survey of land use and biodiversity, they’ve discovered that when natural habitats are converted to farmland or urbanised, the animal species that survive the change in greatest number are those species which carry viruses and bacteria with the potential to spread to us. This is particularly the case, says Rory Gibb of the University College London, with disease-carrying rodent species, bats and birds.

Do past infections by mild cold coronaviruses prepare the immune systems of some people for infection by SARS-CoV-2? Could immune memory T cells made in response to these cold viruses lessen the severity of Covid-19? Alessandro Sette and Daniela Weiskopf of the La Jolla Institute for Immunology lead the team which published the latest contributions to these questions.

Anglerfish are perhaps the weirdest inhabitants of the deep sea. Their sex lives are particularly strange because finding partners in the dark expanse of the ocean abyss is hard. Females are much bigger than males. When a male finds a female, he latches on her body with his teeth and over a couple of weeks, their flesh fuses so he is permanently attached. Her blood supplies him with all the food and oxygen he needs and he becomes an ever present supply of sperm whenever she produces eggs. But this fusion should be impossible. The female’s immune system should be rejecting her partner like a mismatched organ transplant. German scientists have now discovered that these fish do this by giving up the production of antibodies and immune T cells – essential for fighting infections in all other animals including us. It was a shocking discovery for Prof Thomas Boehm at the Max Planck Institute in Freiburg.

(Image: Relatives of heatstroke victims, their heads covered with wet towels, wait outside a hospital during a heatwave in Karachi. .Credit: Rizwan Tabassum/AFP via Getty Images)

Presenter: Roland Pease Producer: Andrew Luck-Baker