Zookeepers are counting their losses after the tragic deaths of around 50 of their 69 penguins due to an avian malaria outbreak.Dozens of Humboldt penguins at Dudley Zoo have died having contracted the disease, leading to an outpouring of sympathy and sadness from zoo fans. Similar to human malaria, avian malaria is a parasitic disease transmitted through the bite of infected mosquitoes. It cannot be passed on to humans or other animal species, but penguins are particularly susceptible to it as they do not have natural immunity to the disease. This is a completely separate disease to avian flu, which...