External Parasites Flashcards
Define
Symbiosis
Two organisms living together
Define
Mutualism
Two organisms living together where both benefit
Define
Commensalism
Two organisms living together
* one benefits
* other neither benefits or is harmed
Parasitism
Organism lives on or in host and may be pathogenic
* ectoparasite = external
* endoparasite = internal
Define
Obligate Parasite
Parasite unable to lead a free-living existence
Facultative Parasite
Organisms that are non-parasitic in nature by can become parasitic in certain hosts
Reservoir Host
Vertebrae host that has the parasite and is source of infection
Definitive Host
Harbors the adult, sexual, and mature stages of parasite
Arthropods
- Exoskeleton with segments
- True body cavity
- Circulatory, Excretory, Nervous, Reproductive Systems
- Jointed legs
- Egg reproduction (2 sexes)
- Insects vs Arachnids
Insects
Body Anatomy
- 6 Legs
- Head / Thorax / Abdomen
- May or may not have wings
- Antennae
- Mouthparts for chewing/sponging/sucking
Insects
Examples
- Fleas
- Lice
- Flies
Arachnids
- 8 legs
- Cephalothorax / Abdomen
- No antennae
- Mouthpart for cutting
Arachnid
Examples
- Ticks
- Mites
Flea Life Cycle
- Eggs on host fall off and into environment
- Eggs hatch into larvae - feed on organic debris (poop)
- Larvae spin cocoons
- Adults emerge based on vibration, pressure, heat, noise, CO2
- Adults always parasitic - can live for extended periods of time in environment
Dog and Cat Flea
Technical Name & Info
Ctenocephalides (felis and canis)
* anemia with heavy infestation
* saliva is antigenic - hypersensitivity and dermatitis
* observe near base of tail, ventral abdomen, and chin
Fleas as Vectors
- Dipylidium caninum
- Plague
- Rickettsia (typhus)
Lice
Technical Name
- Mallophaga
- Anoplura
Lice Severity
More severe in:
* young/old/poorly nourished
* overcrowded conditions
* colder months
Mallophaga
- Mouthpart = biting/chewing
- Moves rapidly
- Smaller
- Broad, rounded head
Anoplura
- Mouthpart = sucking
- Moves slowly
- Larger size
- Long, narrow head
Mallophaga Lice
Anoplura Lice
Mites and Ticks
Technical Name
Acarina
Hard Ticks
Technical Name
Ixodidae
Brown Dog Tick
- Rhipicephalus sanguineus
- Transmits E. canis and Babesia
Rhipicephalus sanguineus
(brown dog tick)
American Dog Tick
- Dermacentor variabilis
- Transmits Rocky Mountain Spotted Fever - treat w/ antibiotics
- Causes tick paralysis (toxic female saliva) - treat w/ removal
Dermacentor variabilis
(american dog tick)
Blacklegged or Deer Tick
- Ixodes scapularis
- Transmits Lyme disease
Ixodes scapularis
(blacklegged or deer tick)
Lone Star Tick
- Amblyomma americanum
- Causes Masters Disease - rash illness (presents like lyme in humans)
- Can also cause Rocky Mountain Spotted Fever
Amblyomma americanum
(lone star tick)
Sarcoptes Mites
- Burrow/ tunnel into superficial layer of skin
- Localized inflammation and hair loss
- Prefers areas with little hair - ears, elbows, hocks, ventrum
- Spreads rapidly - direct contact
- Extreme pruritus
- Diagnose with superficial skin scrape
Sarcoptes Mite
Demodex Mites
- Burrowing mite into hair follicles and sebaceous glands
- Immunodeficiency needed for infestation
- Causes hair loss, thickening skin, and pustules
- Not pruritic unless secondary infection
- Not contagious (though transferred to babies from mom in dogs)
- Deep skin scrap needed to diagnose
Demodex Infestations
Types
Localized
* red, scaly lesions on face or forelegs
* goes away on own once immunocompetent
Generalized
* patchy fur and alopecia over entire body
* treatment recommended
Pododermatitis
* confined only to paws - last stronghold
* often generalized during recovery
* may require biopsy to diagnose
Demodex Mite
Otodectes Mites
- Ear mites
- Live in external ear canal of cats and dogs
Otodectes Mite
Cheyletiella Mites
- Walking dandruff
- Causes dry, scaly dermatitis with dandruff
- With or without pruritus
- Find on dorsum above tail and neck
- Highly contagious
Cheyletiella Mite
Rocky Mountain Spotted Fever
Vectors and Symptoms
Transmitted by
* Dermacentor
* Amblyomma americanum
Symptoms
* fever
* chills
* headaches
* muscle pains
* rash
Tick Paralysis
Vector and Symptoms
Transmitted by
* Dermacentor
Symptoms
* paralysis progresses back to front
* anorexia
* lethargy
* muscle weakness
* ataxia
* nystagmus
Lyme Disease
Vector and Symptoms
Vector
* Ixodes scapularis
Symptoms
* fever
* shifting leg lameness
* swelling in joints
* lethargy
* anorexia
