KEY
Note Taking Guide:
Topic # 3053
Parasites
Animal Health Parasites
Their Life Cycles and Classification
Infectious Agents Causing Disease can be divided into
Three General Groups:
Bacteria
Viruses
Parasites
Bacteria
• Simple plant life
• Microscopic
• Can be Pathogenic and beneficial
• Live outside of host
• Sensitive to antibiotics
Viruses
• Are Ultra-microscopic
• Live in tissue of host cells
• Are resistant to antibiotics
• highly contagious
Parasites
• Live in, on, or at the expense of the host.
• Infections develop slowly
• Difficult to eradicate completely
• Animals do not develop resistance
• Animals may not show symptoms
• Host-specific
• Include fungi, protozoa, arthropods, and helminths
The Parasites in this Group
• Cause tissue damage
• Absorb nutrients
• Suck blood and lymph
• Obstruct passages
• Causes growths
• General irritation
• Secondary infections
• Cause serious economic damage
Non-infectious Agents That Cause Disease
• Chemical and poisons
• Poor Nutrition
• Injuries
• Physical stress from breeding, conception, lactation, and birth
• Any other stress or trauma that weakens the animal or its immune system to secondary
infections
Causes Of Disease
• Nutritional Defects
- Result from unbalanced diets
• Physiological Defects
- Improper functioning of body parts
• Morphological Defects
- Physical disabilities
• Pathogenic Organisms
- Tiny living things capable of causing disease
Life Cycle of Tapeworm in a Sheep
Ascarids
Strongyles
Beef and Pork Tapeworms
The Life Cycle of Flies
Occurs in Four Stages
Lice
Ticks