Intro to Parasitology Flashcards
Parasite definition
“Dependence for food and shelter”
Endoparasite
On the inside (gut, heart, lungs, blood, repro tract)
Types of Endoparasites
- Protozoa; coccidia, malaria, tick fevers
- Worms; nematodes, cestodes, trematodes
Nematodes
Round worms
Cestodes
Tape worms
Trematodes
Flukes
Ectoparasites
On the outside (skin & adnexa)
- Insects; flies, midges, mosquitoes, fleas, lice
- arthropods; ticks and mice
Definitive host
Host in which parasite become sexually mature
Intermediate host
(obligatory) temporary environment for parasite
- does not reach sexual maturity here but can undergo asexual reproduction/obligatory development
Paratenic (transfer) host
Parasite does not undergo development, but remains alive and infective to another host
Vectors
Any organism (esp arthropods) that serve as IH as well as carriers for protozoans or other small parasites
Reservoir host
Animals that harbour an infection that can be transmitted to humans
3 Parasite factors
- Dose
- Virulence
- Infectivity
5 Host factors
- Innate resistance
- Previous exposure
- passive immune status (neonates)
- Reproductive status (preg/lact. vs non-preg, sterile vs intact)
5 Environmental factors
- Animal stocking density
- animal movement between groups (rotational vs cont. grazing), quarantine of new stock
- Housing (e.g. ventilation, sanitation)
- Environmental conditions (e.g. temp, rainfall)
- Nutrition (energy balances)
HxP interaction ultimate goal
Both host and parasite to survive and reproduce
How clinical signs are caused
- removal of e.g. blood, metabolites
- loss of body fluids
- interference w absorption (ingested foods)
- blockage of e.g. heart
- irritation; larvae in airway
- migration; into CNS
=> ‘ill thrift’, diarrhoea, anaemia
Production of pathology
- production of toxin/excreted foreign materia
- migration through tissues/ residence in tissues
- host reaction; allergies and inflammation
Host specific
Narrow host range, well adapted, niche relation
- Often seen IH»DH relations
Non host-specific
- Broad host range
- Possibility of paratenic host
- Possibility of zoonosis
Direct parasite life cycle
- Free-living stages outside host
- Infective stage in environment
- Parasitic stages in final (definitive) host
Indirect life cycle
Consists of definitive (final) and IH
- IH (rabbit), vector-parasite (fleas), unrelated hosts (snails for flukes)
- when IH involved, LC is INDIRECT