Ectoparasites and protozoa Flashcards
List some examples of Ectoparasites
Lice, mite and ticks
List some examples of protozoa
Giadia lambia, Entamoeba histolytica, Toxoplasma gondii
What is the difference in definitive host, intermediate host and parantenic host, and reservoir host?
Definitive: parasite reaches sexual maturity
Intermediate: Development but not sexual maturity
Parantenic: Parasite remains infective but no development
Reservoir: animal that is normally infected with the parasite and can infect others
What is pediculosis? list symptoms and infectious organisms
Lice infections from Pediculus humanis (body), P.capitis (head) P.pubis (pubic hair). Symptoms include itch, macules
Describe the lifecycle of lice and how you would intervene to treat infection.
32-35 day cycle.
Louse emerges from egg on hair, wihin 17 days the first/second/third moult is formed > adult lice (F larger than M). Female can lay 3-9 eggs per day.
Rx: topical insecticide
Describe the lifecycle of scabies
Adult F lays eggs a borrows in epidermis > eggs hatch and release larvae > larvae molt into nymphs > mating > begin lifecycle again.
Causes itch and dermatitis
Where does scabies infect and how would you dx. and Rx. it?
Finger webs of hands and other flexor surfaces.
Dx: skin scraping
Rx: Ivermectin topical
Why are ticks important/dangerous?
They are commonly vectors for other bacterial, viral etc. infectious agents. They only need a short period of contact as the female gets the blood meal
Describe how entamoeba histolytica causes disease
Faecal oral rout > infects colon tissue > causes large volume diarrhoea > dehydration and malnourishment
Haematogenous spread = liver and brain abscess
How do you Dx and Rx entamoeba histolytica infection?
Dx: cysts in diarrhoea
Rx: Metronidazole + paromomycin
Describe how giadia intestinalis causes disease.
Faecal oral spread > infect GIT > sub acute diarrhoea > chronic malabsorption > persistant nausea and abdominal pain
How would you Dx and Rx giadia?
Dx: cysts in faeces
Rx: Single dose of Tindazole
Describe how toxoplasma gondii causes disease
contaminated water or eating undercooked meat > obligate intracellular parasite > persistant usually asymptomatic infection > cysts stay for life
Can cause CNS lesions and Occular disease
When is infection with toxoplasma gondii dangerous?
Immunocompromised
Pregnancy
neonate
HIV patients
Give examples of roundworms, tapeworms, flukes
Roundworm: Pinworm, ascaris, Strongyloides
Tapeworm: Echinococcus, Taenia
Fluke: Schitsosoma
Describe the lifecycle of pinworms (enterobius vermicularis
ingestion > larvae hatch in small intestine > mature in colon and migrate to perianal region > eggs on perianal folds > itch > female crawls out at night to lay eggs > transmission
How would you Dx and Rx pinworm?
Dx: detection of eggs (stickytape test)
Rx: Antihelminthics
Describe the lifecycle of ascaris lumbricoides?
Grow in plants > ingestion of cyst > small intestine hatch then mature > hepatic circulation > lungs > alveoli > trachea > re-swallow.
Also excrete in faeces unfertilised and fertilised cysts
Cause pneumonitis, intestinal obstruction (cholecystitis
How would you Dx and Rx ascaris?
Dx: Eggs in faeces or imaging
Rx: Antihelminthics
Describe the life cycle of strongyloides stercoralis
hatch in soil and borrow through skin > bronchotracheal migration > embryonisation in colon > can autoinfect and larvae excreted in faeces
If excreted > develop into mature free-living worms > eggs are produced and fertilised > infective form can penetrate skin again
How would you Dx and Rx strongyloides?
Dx: eggs in faeces and serology
Rx: antihelminthics
Describe the life cycle of schistosoma
swim in infected water or eat fresh water snails > Enters blood > portal vein > faeces > hatch in water > fresh water snail infection > become infectious
Can have acute infection of be a chroni carrier where the eggs lodge in skin or liver causing acute local inflammation
How would you Dx and Rx Schistosoma?
Dx: eggs in faeces, serology
Rx: antihelminthics
Describe the lifecycle of Echinococcus granulosus infection.
Definitive host = dog > dog ingests cysts > become adult in small intestine > fecal excretion of embryonated eggs > human or sheep (intermediate host) ingestion > penetration of intestine wall > in humans can cause hydalid cysts in heart, lung, liver, spleen, bone. In sheep they excrete cysts which are then ingested by dogs.
Humans are not necessary for lifecycle
how would you Dx and Rx Echinococcus?
Dx: imagin and serology
Rx: antihelminthics followed by surgery to remove cysts
Describe the lifecycle of Taeniasis
eggs contaminate vegitation > pigs and cattle eat infected vegitation > hatch and migrate into musculature > develop cysts in muscle > Humans eat raw, undercooked infected meat > Adults attach to intestine wall > eggs in faeces
How would you Dx and Rx tapeworm infections
Dx: imaging ans serology
Rx: antihelminthic with caution because the immune response can lead to epileptic seizurea
