Pathogens

Definition An organism or virus that causes disease in its host.

Example # 1 Influenza is caused by viruses

Example # 2 Tuberculosis is caused by bacteria

Example # 3 Thrush is caused by fungi aka yeast infection (candida albicans)

Example # 4 Malaria is caused by protozoa P. falciparum, P. vivax, P. ovale, and P. malariae Anopheles mosquito

Example # 5 Schistosomiasis (bilharzia) is caused by flatworms

Example # 6 Hookworm is caused by roundworms Ancylostoma duodenale and Necator americanus.

Transmission of Pathogens Contact Touch, pathogen enters through skin Cuts Skin cut or punctured by infected object Droplets Droplets containing pathogens are sneezed out by infected person and breathed in by another Food or Water Enter body through soft gut wall Sexual Intercourse Enter body through soft mucus membranes of penis or vagina Insects Suck blood out of infected person and transmit pathogens to another

Tuberculosis—A Bacterial Disease Cause Mycobacterium tuberculosis Rod-shaped bacterium Malnutrition, overcrowding, stress increase chances of infection

Tuberculosis Transmission Droplets A rare form of TB can pass from cow’s milk to humans

Tuberculosis Effects Lungs infected with TB bacteria Phagocytes move to lungs and engulf bacteria Bacteria survive and breed inside phagocyte Tubercles form in lungs—small, rounded swellings containing infected phagocytes First infection is usually not severe Re-infection results in chronic TB which gradually destroys the lung tissue Fever, loss of appetite, weight loss, persistent cough, coughing up blood Infection can spread to lymph nodes, bones, and gut Over 3 million deaths/year world-wide caused by TB

The next slide is kind of gross

Antibiotics Used to treat bacterial diseases Bacterial cells are very different than human cells so bacteria can be targeted and killed without harming human cells Viruses use human cells as hosts. If a virus was targeted with an “antibiotic,” human cells would be harmed.