Pathogens reach new hosts in different ways, and knowing the route tells us how to stop it. Cholera bacteria spread in contaminated water, so the spread is reduced by providing clean drinking water, treating sewage and washing hands before handling food. Tuberculosis bacteria are airborne, spread in droplets when an infected person coughs or sneezes. The spread is reduced by covering the mouth, good ventilation, and isolating and treating infected people.
The fungus that causes Chalara ash dieback is also airborne, spreading as spores. Infected trees can be destroyed and the movement of ash plants restricted. Malaria is spread by an animal vector, the mosquito, which picks up the protist from an infected person and passes it on when it bites the next. The spread is reduced by mosquito nets, insect repellent and removing stagnant water where mosquitoes breed.
For separate Biology, Helicobacter bacteria that cause stomach ulcers pass by oral transmission, through contaminated food, water or saliva, so good hygiene helps. Ebola is spread by direct contact with infected body fluids, so patients are isolated and staff wear protective clothing.