Symbiosis
living together" occurs between two living organism of different sepcies
Parasitosis
Parasite is present on or in the host and there ARE clinical signs of the infection
Parasitasis
Parasite is present on or in the hose and there ARE NO clinical signs of the infection
Commensalism
One symbiont benefits from association, the other is neither helped nor harmed (ex: barnacles on whales)
Mutualism
Both symbionts benefit from association (ex: bacteria in the stomach that aid in digestion and provides the organism a place to live)
Phoresis "to carry
Small organism is mechanically transported by the larger symbiont (ex: flies transport bacteria from one animal to the next)
Predator/Prey
Short term; one symbiont benefits at the expense of the other
Parasitism
One symbiont, the parasite, lives in or on the other, the host
Parasitology
Study of parasites / diseases caused by them
Parasite
Smaller organism that lives in or on a larger organism at the expense of the larger organism
Endoparasite
Lives IN the body of the host (ex: hookworms, roundworms, whipworms)
Ectoparasite
Lives ON the body (ex: fleas, ticks, flies)
Zoonosis
Any disease transmissible from animals to humans
Stenoxenous
Parasites have a narrow range of desirable hosts
Euryxenous
Broad range of desirable hosts
Obligatory parasite
Depend on host for survival (ex:tick, lice)
Facultative parasite
Free living organism that DOES NOT rely on host to complete life cycle (ex: fungi on trees)
Incidental parasite
Parasite found in a HOST that it usually doesnt infect (ex: heartworm in humans)
Aberrant parasite
Found in TISSUES that it does not usually infect (ex: heartworm larva in the brain of a cat)
Permanent
Refers to ectoparasites; stays on the host through entire life cycle
Temporary
Gets on the host to feed then returns to environment
Pseudoparasite
Organisms or objects that appear to be parasites but are NOT
Definitive host
harbors parasite in the adult, reproductive stage (ex: canine heartworms)
Intermediate host
Parasites in its immature stage (ex: female mosquitos are intermediate host for heartworms)
Paratenic host (transport host)
- Harbors immature parasite in tissues
- parasite doesnt develop
- definitive host must eat this host for the adult parasite to develop
Reservoir host
Natural source of a parasite for humans or domestic animals (not affected by host)
Trematodes
Flukes
Cestodes
Tapeworms
Nematodes
Roundworms, lungworms, heartworms
Arthropods
Ticks, fleas, lice, flies, mites
Hookworm (ancylostoma spp.)
Cutaneous (skin) larval migrans
- caninum (canine hookworm)
- tubaeformae (feline hookworm)
- uncinaria stenocephala (nothern canine)
Roundworms (toxocara spp)
Visceral (liver) larval migran & ocular (eye) migran
Whipworms (trichuris spp.)
No zoonotic potentional (polar plugs)
Broadfish tapeworm (diphyllobothrium latum)
Diarrhea and cramping
Beef / Pork tapworm (taenia sollum)
Diarrhea and cramping
Baylisascaris Procyonis
Raccoon round worm
Oviparous
Female lay eggs; round worms
Ovoviviparous
Eggs larvate in uterus; female lay eggs containing L1 larva, threadworms
Viviparious
Eggs larvate and hatch in uterus; heartworms
Ascarid (egg type)
Unembryonated
Strongylid (egg type)
Morulated; embryo at early stage
Trichurid (egg type)
Polar plugs
Spirurid
Larvated
Transplacental infections
- Activated when dog is pregnant
- Major route of infection for puppies
Transmammary infections
- If mother is exposed to infection in late pregnancy or while nursing
- Passes to the pup through the mothers milk
Toxocara cati (roundworm)
- Zoonotic transmission by ingestion of egg
- Paratenic host is important
- Cats: definitive host
- Prepatent period: 8 wks
Toxocara canis (roundworm)
- prepatent period: 3-4 wks
- Definitive host: dog
Hookworm (ancylostoma)
- resembles a fishing hook
- Dog: definitive host
- small intestines
- direct life cycle
- strongylid
Whipworms (trichuris vulpis)
- definitive host: dogs
- direct life cycle
- L1 (infective stage)
- unembryonated
- polar plugs
Strongyloids spp (intestinal threadworms)
- Definitive host: carnivores and primates
- Zoonotic; dogs (s. canis) human (s. stercoralis)
- often asymtomatic
- Facultative - homogenic and free living
- L3 infective stage
Spirocerca lupi (esophageal worm)
- cats and dogs
- can turn into tumor (sarcoma)
- causes difficulty swallowing and vomiting
- indirect life cycle "paperclip shape
Aelurostrongylus abstrusus
- feline lungworm
- cats
- indirect life cycle, snail
- larva coiled up, tail is in the center
Eucoleus aerophilus
- fox lungworm
- fox, dog, cat
- direct life cycle
- more rounded polar plugs and smaller than trichuris
Pearsonema plica
- bladder worms
- indirect life cycle
- flat polar plugs
Dioctophyma renale
- giant kidney worm
- host: dog, mink
- indirect life cycle
Thelazia californiensis
- indirect life cycle
- found in the eyes
- symptoms: conjunctivitis; corneal ulcer