Infectious Diseases

Viruses Virus- a tiny, disease-causing particle that invades a healthy cell and instructs that cell to make more viruses. Viruses are a non-living thing. Some viruses can be spread through direct person-to-person contact. Ex. Shaking hands or kissing. Other viruses are spread through indirect contact. Ex. Sneezing or sharing a drink. Vaccine- Medicine that contains killed or weakened pathogens and is given to protect your against a particular disease. Vaccines stimulate your immune system to produce antibodies. Antibody- Chemical that your body produces to fight invading pathogens. www.brainpop.com viruses

Bacteria Bacteria are living things and are more complex than viruses. Bacteria- extremely small, single-celled organisms that do not have a nucleus. Most bacteria can live on their own and they live everywhere. Bacteria can be spread through direct or indirect contact. Most bacteria is harmless to humans, some bacteria can also be helpful. Examples of disease caused by bacteria include whooping cough, anthrax, tooth decay, and some forms of food poisoning and ulcers. www.brainpop.com Bacteria

Controlling Bacteria Washing your hands. Keeping your kitchen clean. Most bacterial diseases can be treated with antibiotics. Antibiotic- a medicine used to stop the growth of or to kill bacteria and other microorganisms. *Antibiotics are not used for any noninfectious disease.

Protozoa and Parasites Protozoa- small, single-celled organisms that have a nucleus. They are more complex than bacteria. Parasite- organism that gets its food from another organism, called the host, without killing the host. Example: Mosquitoes, Leeches.

Protozoa and Parasites Most protozoa are harmless to humans but few can cause illness. Giardia is protozoa that can be found in contaminated water supplies. Giardia can cause stomach upset, cramps, and diarrhea in humans. They are relatively rare in the United States. Plasmodium- is a parasite that causes malaria in humans. Plasmodium is carried by certain kinds of mosquitoes. Malaria is usually found in tropical countries and is rare in the United States. Antibiotics and other drugs are used to treat most diseases caused by protozoa and other parasites.

Fungi Fungi- complex organisms that cannot make their own food. Fungi break down other substances and absorb the nutrients from them. There are over 100,000 species of fungi. Most fungi is harmless to humans and some fungi such as yeast and edible mushrooms are useful. The most common fungal diseases are athletes foot and yeast infections. Fungal infections can be spread by person-to-person contact. Others can be spread by fungal spores in the air, water, or soil. Most fungal medicines can be treated with medicines applied to the skin, others can be treated by oral medications.