Parasitology - Exam 1 Lecture 5 (Lice)

Question 1

In regards to Lice, what is their life cycle and discuss the basics

Answer 1

• incomplete metamorohosis
• Egg –> Nymph (3) –> Adult
• Need a physical bridge to move from host to host (direct contact; fomites)
• usually sedentary –> remain attached to hair follicle or feather
• Common on animals housed inside (and close togther)
• outbreaks most common in the winter, when animals huddle close otgther
• Individual suscpetibility varies –> especially based on general health status

Question 1

Regarding lice, discuss ehich species of lice correlate hwich each animal species

Answer 1

Dogs:
- Trichodectes –> chewing
- Linognathus –> sucking

Cats: Felicola –> chewing

Cattle:
- Haemotopinus, Linognathus, and Solenopotes –> sucking
- Bovicola (Damalinia) –> chewing

Horses: Damalinia –> chewing

Main point here is that this is easy because there is ually only one species per animal (or one species of each type - Anoplura and Mallophaga)

Question 2

Regarding Lice, discuss the effects on the hgost

Answer 2

• Anoplurans suck blood: 1) anemia in high numbers 2) hypersensitiivty reactions
• Mallophagans eat skin cells, epidermal secretions, keratin: 1) do not suck blood 2) hypersensitivity reactions
• Hair loss syndrome of black tailed deer
• pruritis > hair loss
• ## Lice are opportunistic and infestations are affected by: nutrition, stress, crowding, concurrent infections, genetics, and immune status

Question 3

Regarding lice, discuss disease transmission

Answer 3

• Lice are generally poor disease vectors
• few excetions: Hof louse Hematopinus suis transmits swine pox and Mycoplasma and canine chewing louse Trichodectes canis may be an intermediate host for the tapeworm Dipylidium Caninum

Question 4

Regarding lice, discuss the diagnosis process

Answer 4

Careful skin inspection –> magnification helps
- thick coats tend to be more difficult to evelauate
- Use scotch tape to catch and evaluate microscopically
- Morphology –> sucking verus chewing

Question 5

Regarding treatment of lice, discuss ths specifics of it

Answer 5

Dogs and cats:
- Fipronil
- Imdacloprid
- Pyrethrins –> dogs only,NOT CATS
- Macrocyclic lactones –> especially Selamectin

Large animals: organophosphates, macrocyclic lactones, and pyrethrins

• **Macrocyclic lactones usually require one treatment
• Organophosphates usually require 2 treatments about 2 weeks apart
• Pour-ons better for chewing lice
• Injectables better for sucking lice
• w**