Common illnesses
Ashlee Gibson
Topic #
Infectious Agents that Cause
Disease
• Bacteria
• Virus
• Parasite
Bacteria
• Are the most simple form of plant life.
• Contain no chlorophyll (therefore need no
sunlight for survival).
• Are microscopic one-celled organisms that vary
in size and shape.
• Can be pathogenic and in other cases are beneficial to man
(Common ones are used in the fermentation of vinegar and
in cheese making.).
• Generally live outside host cell.
• Are sensitive to antibiotic drugs such as
penicillin.
Example of Bacteria Diseases
Virus
• Are ultra-microscopic.
• Live within the tissue of host cells and
therefore, cannot be killed with
medications that circulate only in body
fluids (unlike bacteria).
• Are resistant to antibiotic drugs.
• Most are highly contagious.
Example Viral Diseases
Parasites
• Parasites are organisms living on, in or at the expense of
the host.
• Parasite infections develop slowly and are difficult to
eradicate completely.
• Animals do not develop immunity, to parasites, although
some resistance is apparent between age groups.
• Some animals do not show many symptoms, others may
show symptoms such as dull hair coat, lethargic
behavior and loss of weight.
• Most parasites are host-specific (only live in certain
types of animals).
Parasites Continued
(1) Cause tissue damage through migration and
consumption.
(2) Absorb nutrients from the host's g.i. tract (gastrointestinal system).
(3) Suck blood or lymph from the hosts body.
(4) Obstruct of passages.
(5) Cause nodules or growths internally and externally.
(6) Cause general irritation internally and externally.
(7) Transmit other types of diseases to the host.
(8) Open the body to secondary infection.
Parasite Disease Example
Non-infectious Disease Causing
Agents
•
•
•
•
Chemicals and poisons.
Poor nutrition.
Injuries.
Physical stress found during breeding,
conception, lactation and birth.
• Any other kind of stress or trauma that
weakening the animal and its immune
system, making it more susceptible to
other secondary infections.