AB2, L4: Introduction to Veterinary Parasites

Given definition, answer w/ term

Parasite

• An animal or plant that lives in or on a host from which it obtains nourishment from. They often co-evolve with their hots

• The host does not benefit from this association, and is often harmed by it

• Classified as pathogens

Protozoans, helminths, and arthropods

List the 3 main categories of parasites

Protozoans

1 of the 3 Main Categories of Parasites:

• Single cell animals

Helminths

1 of the 3 Main Categories of Parasites:

• Subcategories include:

  • Nematodes – roundworms

  • Trematodes – squished, cornflake appearance

  • Cestodes – tapeworms

Arthropods

1 of the 3 Main Categories of Parasites:

• Subcategories include:

  • Insects

  • Ticks

  • Mites

High production, low survival

1 of the 2 Types of Parasite Reproductive Mechanisms:

_______ production, _______ survival

• Definition: Massive feeding to support reproduction, low chance of ingestion by intermediate host

• Example: Tapeworm

• Most common mechanism

Low production, high survival

1 of the 2 Types of Parasite Reproductive Mechanisms:

_______ production, _______ survival

• Definition: Selective host number, emerging directly from host

• Example: Warble fly

Overdispered distribution

Distribution most commonly in populations of animals with parasites

• Note, most animals have a very low burden, and only a few have a very high burden

• The prevalence of infection is high, but the prevalence of disease is low

Endemic stability

• Definition: Host populations consist of individuals with acquired immunity, poor immunity, or no immunity

Pruritic stress

1 of the 5 Harms Associated with Parasites:

• Definition: Aka, itching

• Example: Sarcopts scabei buries into the dermis and causes mange. Most commonly seen in dogs and pigs

Biting

1 of the 5 Harms Associated with Parasites:

• Example: Sharp mouthparts on Stomaoxys calcitrans (stable fly) fly irritate animal, associated with drop in milk production

Acute inflammatory response

1 of the 5 Harms Associated with Parasites:

• Example: Babesia infected red blood cells leads to release of haem and exponential rate of infection of red blood cells, which ultimately leads to an acute inflammatory response

Physical damage to host tissues and organs

1 of the 5 Harms Associated with Parasites:

• Example: Coccidiosis – massive reproduction of Eimeria protozoa in poultry disrupts the epithelium of cecum

Competition for resources

1 of the 5 Harms Associated with Parasites:

• Example: Parascaris equorum, a roundworm which commonly presents as clinical signs in foals, will monopolize nutrients in gut

Dead-end hosts

What kinds of hosts are humans typically in the zoonotic disease process?

Louping ill virus

• Transmitted by: Ixodes ricinus ticks

• Infects: Sheep and red grouse

• Symptoms: Fever, depression, neurological signs, “________ gait” in sheep, & death

• Vector-borne, zoonotic disease that is continuing to expand due to global warming

African horse sickness virus

• Caused by: Orbivirus

• Transmitted by: Culicoides imolica midges

• Infects: Horses

• Symptoms: Fever, respiratory signs, cardiac signs, death

• Prevention: Live attenuated vaccine

Blue tongue virus

• Caused by: Orbivirus

• Transmitted by: Culicoides spp

• Infects: Ruminants, most severe in sheep

• Symptoms: Fever, swelling of head/neck, ocular/nasal discharge, lameness, respiratory signs, milk drop (cattle), death

• Prevention: Vaccine

Schmallenberg virus

• Caused by: Orthobunyavirus

• Transmitted by: Midges

• Infects: Sheep & cattle

• Symptoms: Fever, milkdrop, diarrhea, abortion, stillborns, and congenital abnormalities

• Cyclical outbreaks seen

Shamonda-like virus

• Caused by: Orthobunyavirus

• Transmitted by: Midges

• Infects: Cattle

• Symptoms: