Human infections have different pathogens. Measles is a viral infection spread in droplets and causes a fever and red rash. Salmonella food poisoning is a bacterial infection from contaminated food and causes fever, vomiting and diarrhoea. Athlete's foot is a fungal infection that makes the skin between the toes itchy and flaky.
HIV is a viral sexually transmitted infection. It spreads by sexual contact and by exchange of body fluids such as blood, for example by sharing needles. HIV damages the immune system. In late stage infection, called AIDS, the body cannot fight other infections. Antiviral drugs control HIV. Chlamydia is a bacterial sexually transmitted infection that often has no symptoms. It can cause infertility, but antibiotics treat it, and condoms reduce the risk.
Tobacco mosaic virus (TMV) is a viral plant disease. It gives leaves a mosaic of yellow and green patches, so there is less photosynthesis and growth is poor. Barley powdery mildew is caused by the fungus Erysiphe graminis and makes white powdery patches on leaves. Crown gall disease is caused by the bacterium Agrobacterium tumefaciens and produces swellings on stems and roots.