Parasitology 13 Ectoparasites

T/F: Mosquitoes are ectoparasites

False

What species carries malaria?

Anopheles mosquito

Arachnid bugs

Arachnids, ticks, mites

Insect bugs

lice, flea

Cimex spp.

• common name?

• UNUSUAL vector of?

• cause what symptoms?

• other traits?

• bed bugs

• T. cruzi

• allergic inflammation from bites

• stink glands that cause distinctive odor

What is this?

Cimex (bed bugs)

Myiasis — what is it?

infection with the larval stage of various flies

What flies cause myiasis?

• Dermatobia hominis (botfly)

• Cochliomyia hominovorax or Chrysoma bezziana (screwworm)

• Cordylobia anthropophaga (tumbu fly)

• Cuterebra, Oestrus, Wohlfahrtia

What is this?

botfly

Cerebral myiasis

• is it rare?

• what species causes it?

  • how does it attack?

• yes

• Cochliomyia hominovorax

  • invades viable tissue

What is this?

Cochliomyia hominovorax (screwworm)

Cordylobia anthropophaga (tumbu fly)

• distribution?

• causes what?

• eggs laid where?

• how infect host?

• life stages and times?

• tropical Africa

• myiasis

• laid on feces or urine stained soil or clothes

• larvae hatch in 4 days; penetrate skin

• leave host in 8-10 days

Lucilia sericata

• “good maggot” because determines time of death and used for maggot therapy

• causes disease in sheet or other liverstock

Definitive identification of ectoparasites through what?

spines and spiracular plates

Head/body lice

• which species is which?

• who is infected?

• distribution?

• who more at risk?

• P. capitis is head lice

• P. corporis is body lice

• humans only

• feeds on blood several times

• worldwide distribution

• children and females

P. humanus humanus

• resides where?

• eggs where?

• resides on clothing; eggs glued to clothes

P. humanus capitis

• resides where?

• eggs where?

• resides in scalp; no known vectors; eggs found in hair

Treatment for lice

• lice-killing lotion/shampoo with 1% permethrin

• second defense is lindane

Sarcoptes scabiei (itch mite)

• distribution

• where on the body?

• how it infects

• most at risk?

• worldwide

• warm/moist areas

• burrows into subcorneal layers of skin

• HIV/AIDS patients

Scabies diagnosis? Treatment?

skin scraping

• permethrin cream (5%) or ivermectin if immunosuppressed

• wash clothes in hot water

What is this

Scabies mite/itch mite

Ixodidae (hard ticks)

• list the genus’ and how many hosts they have

Amblyomma

Dermacentor - 3

Hyalomma - 2

Ixodes - 3

Soft ticks (argasidae)

• list the genus’ and hosts they have

Rhipcephalus - 1 or 3 hosts (mainly birds)

Ornithodoros - multihost

Which hard tick species causes babesiosis?

Ixodes

Tick paralysis

• caused by

• symptom

• what is required

• caused by Dermacentor and Ixodes

• acute ascending paralysis — fatal

• tick must be attached 4 days before symptoms

What happens when you consume mammal-derived products (milk, meat, cheese, etc) after a tick bite?

you get a serious allergic condition

Tick life cycle amongst hosts

• larva attaches to and feeds on first host in summer

• nymphs attach to second host in spring

• nymphs molt and attach to third host as adults in fall for feeding/mating

• lay eggs in spring

brown recluse spider (loxoscele reclusa)

• hobo spider

• lives in gardens and burrows — no spider web

• cause skin necrosis, kidney failure, hemolysis, shock

What is this

brown recluse

Black widow spider (L. mactans)

• warm, southern USA

• sexual cannibalism

• potent venom

• lack powerful chelicerae

Lactrodectism phases, lengths, symptoms

• exacerbation phase is 24 hours (pain at bite, muscle cramps, dizziness, insomnia, etc)

• Dissipation phase is 1-3 days post bite (symptoms decline)

• residual phase is weeks to months (muscle spasm, tingling, weakness, paralysis)