Viruses: Tiny particles that invade & replicate within living cells.

Bacteria: Cause disease by either breaking down the tissues of the infected organism or releasing toxins that harm the body.

Protists: Causes malaria.. Spread by mosquitoes

Worms: Parasitic worms that cause a number of serious human diseases.

Fungi: Some fungi can penetrate the outer layers of skin.. Ex. Athlete’s foot.

Physical contact: Some diseases can be spread by direct contact. Some can be indirect contact.. Ex passed through the air or touching objects that an infected person has touched

Contaminated food & water: Food poisoning… Bacteria can grow quickly in warm, partially cooked food. Water can also carry disease.. Poor sanitation & untreated sewage.

Infected animals: Animals can spread diseases… animals that carry disease are called vectors.

Disease: any change, other than an injury, that disrupts the normal functions of the body.

Pathogen: disease-causing agents… these are referred to as “sickness makers.”

Germ theory of disease: Infectious diseases are caused by microorganisms of different types, commonly called germs.

Koch’s postulates: Rules that are used to identify the microorganism that causes a specific disease.

Vector: animals that carry pathogens from person to person… Example - ticks

Antibiotic: compounds that kill bacteria without harming the cells of the human or animal hosts.