Infectious Disease
WHAT IS AN INFECTIOUS
DISEASE?

Bacteria, viruses, protozoans, fungi, and
other parasites called pathogens are capable
of causing a change that disrupts the
homeostasis in the body.

Any disease caused by the presence of
pathogens in the body is called an infectious
disease. The main sources of pathogens are
soil, contaminated water, and infected
animals, including other people

Not all microorganisms are pathogenic; your
body is host to billions of microorganisms,
most of which are bacteria. These
microorganisms have a symbiotic relationship
with your body helping to keep harmful
bacteria and other microorganisms from
growing.

If beneficial organisms are eliminated from
your body, pathogens can establish
themselves and cause infectious disease. In
addition, if beneficial organisms enter areas
of the body where they are not normally
found, these formerly harmless organisms
can become potential pathogens
Disease
Cause
Affected Organ
Transmission
Smallpox
Virus
Skin
Droplet
Influenza
Virus
Respiratory system
Direct contact
HIV/AIDS
Virus
Immune system
Body Fluid
Hepatitis B
Virus
Liver
Body Fluid
Tetanus
Bacteria
Nervous system
Puncture Wound
Strep Throat
Bacteria
Respiratory system
Droplet
Tuberculosis
Bacteria
Respiratory
Droplet
RESERVOIRS OF PATHOGENS

Main source of human disease pathogens is
the human body, these people may or may
not display symptoms of the illness. These
carriers are a significant reservoir of
infectious disease.

Other people may communicate the disease
before they experience symptoms. Animals
are the other main reservoir for pathogens,
making the eradication of certain pathogens
almost impossible.
TRANSMISSION OF DISEASE

1.
2.
3.
4.
Pathogens can be transmitted to a host from a
reservoir four main ways;
By direct contact; exchange of body fluid
especially during sexual intercourse
By an object; people handle contaminate objects
then touch face, nose, eyes, etc…
Through the air; person coughs or sneezes
spreading droplets which are then inhaled
By a vector; insects such as mosquitos, ticks
spread pathogens between hosts or reservoirs