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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. Anopheles mosquito.
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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 Anopheles mosquito • Malaria is caused by protozoa • P. falciparum, P. vivax, P. ovale, and P. malariae
Example # 5 • Schistosomiasis (bilharzia) is caused by flatworms
Example # 6 • Hookworm is caused by roundworms • Ancylostomaduodenale and Necatoramericanus.
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
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.