Types of Pathogens:
Bacterium – single celled organism. Can live almost anywhere. Multiply rapidly – under
perfect conditions, in 15 ½ hours, 1 multiplies into 4 billion. In most healthy
individuals, body’s immune system attacks the invading bacteria.
Virus – not a living cell. Smallest known type of infectious agent. Inner core of genetic
material surrounded by a protective shell. Highly specific in types of cells that
they invade. Usually run course and eventually killed by immune system.
Rickettsias- look like small bacteria. Multiply by invading cells (like the virus does).
Most are found in the intestinal tracts of insects – notably fleas – also mice, ticks,
and mites. Passed to humans and animals through bites or feces on the skin
Protozoan – single celled organisms. Much larger and more complex than bacteria.
Common in tropical areas with poor sanitation.
Fungi – organism that cannot make its own food. Prefers dark, damp environments.
Usually invades deep tissue of hair, nail, and skin.
Diseases by Bacteria:
o Tuberculosis
 Highly contagious infection that most often affects the lungs
 Spread by airborne droplets
 Symptoms include coughing (sometimes with blood), chest pain,
shortness of breath, fever, sweating, poor appetite, weight loss.
o Strep Throat
 Spread by airborne droplets
 Symptoms include sore throat, fever, general feeling of illness,
enlarged lymph nodes in the neck
o Meningitis
 Infection of the membranes covering the brain and spinal cord.
 Bacterial is more dangerous
 Caused by an infection elsewhere in the body (travels through
bloodstream)
 Symptoms include fever, severe headache, nausea and vomiting,
sensitivity to light, stiff neck
Diseases by Virus:
o Common Cold:
 Transmitted by airborne droplets, contact with infected person or
contaminated objects.
 Symptoms include runny nose, sneezing, sore throat, and
headache.
o Influenza
 Transmitted by airborne droplets
 Symptoms include chills, fever, headache, muscle aches, weakness
o Encephalitis
 Inflammation of the brain
 Usually caused by a bite of an infected mosquito
 Starts with a headache and fever, untreated can progress to
hallucinations, paralysis, loss of consciousness, coma
o Meningitis
 Infection of the membranes covering the brain and spinal cord.
 Viral is more mild
 Caused by an infection elsewhere in the body (travels through
bloodstream)
 Flu like symptoms
o Mononucleosis
 Also known as the “kissing disease”
 Spread by direct contact touching, sharing food/drinks
 Symptoms include chills, fever, sore throat, fatigue, swollen lymph
nodes
 Complete bed rest is needed in the care of mono
o Hepatitis A/B/C
 Inflammation of the liver
 Symptoms include Jaundice (yellowing of the skin and whites of
the eyes), fever nausea, loss of appetite, pain in the abdomen
 Severe cases can lead to permanent liver damage
 A spread by food and water contaminated with feces
 B found in all body fluids especially blood
 C spread through infected blood
o HIV
 See HIV Unit
Diseases by Rickettsias:
o Typhus
o Spread by ticks, mites, fleas, or lice
o Symptoms include fever lasting one to several weeks, chills,
headache, muscle pain, body rash
o Also often a painful sore at the site of the bite
Diseases by Protozoan:
Diseases by Fungi:
Ringworm
Athlete’s Foot