Disease

COVID-19

The countries with the 10 greatest number of Covid-19 cases:

The recent upsurge in Covid-19 cases across Spain, France and the UK has been caused by a new variant of the disease that has mutated in Spain and has been carried across borders by tourists returning home. The new variant appears to be more virulent than the older variant.

Night Bites

Artificial light is causing some disease-carrying mosquitoes to track down and bite humans more frequently outside their usually active periods, researchers say. Writing in the American Journal of Tropical Medicine and Hygiene, scientists say that Aedes aegypti mosquitoes, which normally fly and bite in the early morning and during the afternoon, will now bite at night in illuminated areas. They warn that increasing levels of light pollution could increase the chance of infection in humans with diseases such as dengue fever, yellow fever, chikungunya and Zika. Unlike other species that may emerge from the forest to feed on humans and animals, Aedes aegypti evolved with humans and prefers to feed on them.