Pathogens and Communicable Diseases

• DISEASE - A Condition that Impairs the Normal Functioning of an Organism.
• PATHOGEN - An Organism that Causes Disease. Different Types include Bacteria, Viruses, Fungi and Protoctista).
• COMMUNICABLE DISEASE - A Disease that can Spread between 2 Organisms.

See This Free Website for a Table of Stuff we Need To Learn

DIRECT TRANSMISSION

When a Disease is Transmitted Directly from one Organism to Another. This can happen in several ways. (Droplet Infection (Coughing or Sneezing tiny Droplets of Mucous or Saliva onto someone) Sexual Intercourse, or Touching an Infected Organism
e.g.
HIV - Transmitted via Sexual Intercourse
Athlete's Foot - Transmitted via Touch.

INDIRECT TRANSMISSION
When a Disease is Transmitted from one Organism to Another via an Intermediate. An Intermediate can be Air, Water, Food, or Another Organism (Vector)
E.g.
Potato/Tomato Late Blight - Transmitted when Spores are Carried Between Plants. First in the Air, then in Water.
Malaria - Spread between Humans via Mosquitoes (feed on  blood). The Mozzies are Vectors. They Don't Cause Malaria, but they Do Spread the Protoctista that Causes it.

Factors that Affect Disease Transmission
OVERCROWDING
Overcrowded Living Conditions Increase Transmission of many Communicable Diseases.
e.g. TB - Spread via Droplet Infection and is Indirectly Spread because Bacteria can Stay in the Air for a Long Time.

CLIMATE
e.g.
Potato/Tomato Late Blight - Becomes Common during Wet Summers because the Spores need Water to Spread.
Malaria - Common in Tropical Countries because they are Humid and Hot. These are Ideal Conditions for Mosquitoes to breed.

SOCIAL FACTORS
e.g. HIV - The Risk of Infection is High when there is Limited Access to:

• Good Healthcare - Less likely to be Diagnosed and Treated and the Most Effective Drugs would be less likely to be Available, so it is More Likely to be Passed on.
• Good Health Education - Informing people about How it is Transmitted and How it can be Avoided (i.e. Safe Sex)