Mites, Protozoa, Tapeworms, Fungi, Tick-borne Bacteria Flashcards
pt presents with extreme itchiness all over body. Upon examination, you notice a thin, reddish-brown line, punctuated at one end by a red bump. What does this suggest?
scabies burrow (by arthropod Sarcoptes scabiei)
what causes scabies?
arthropod Sarcoptes scabiei
how is scabies spread?
direct skin contact, outbreaks more likely in overcrowded or institutional settings
scabies mites mate on the skin surface, then the female secretes proteolytic enzymes to burrow under the ____ layer of the epidermis
stratum corneum (outermost layer)
in response to scabies infection, the immune system mounts a type __ hypersensitivity reaction
Type IV - cell mediated. Langerhans and macrophages in the skin engulf antigens from mites or their saliva and feces, present these to T cells
Type IV reactions are delayed because of cell-mediated response
patients with scabies infection typically don’t develop itching until 3-6 weeks later. Why is this?
immune system mounts Type IV hypersensitivity reaction, which is cell mediated and therefore delayed
what is the treatment for scabies?
topical cream (permethrin) which is spread over whole body and left on for 8 hours, then repeated 2 weeks later
what goes wrong in crusted scabies?
patient doesn’t mount effective cell-mediated immune response (immunocompromised, elderly, etc). Scabies replicate unhindered and red scaled patches develop but patient isn’t itchy (due to lack of immune response)
very vulnerable to super infection with bacteria
pruritic means
itchy
Plasmodium parasites cause what kind of disease in humans?
malarial disease
What is the most common form of malaria, and also one of the most deadly?
Falciparum malaria (from Plasmodium falciparum)
pt presents with paroxysms (cycles) of fever/shivering/diaphoresis, severe headache, jaundice in eyes, splenomegaly. After taking pt history, you find out they have recently been in an area where mosquito nets are usually used, but they did not have one. What do you suspect?
malaria
what is the primary host for Plasmodium falciparum, which causes malaria in humans? (be specific)
Anopheles mosquito
when female mosquitos draw human blood and transfer Plasmodium parasite, what form is it in?
sporozoite
when Plasmodium parasite begins to colonize hepatocytes, what form/phase is it in?
schizont phase - replicate inside hepatocytes, forming merozoites
after replicating inside hepatocytes, Plasmodium parasites are in what stage of life cycle?
merozoites/merosomes - these can travel through bloodstream undetected because they are covered in liver cell membrane
place the life cycle of Plasmodium parasites in order: schizont merozoite/merosome trophozoite sporozoite
- sporozoite - motile, immature
- schizont - mature, in liver
- merozoites - travel through blood undetected, covered by liver cell membrane
- trophozoite - inside RBC, characteristic ring shape
what are the 2 ways in which Plasmodium parasite (causing malaria) is amplified in host body?
exoerythrocytic phase - inside hepatocytes
erythrocytic phase - inside RBC
3 ways to prevent malaria infection
mosquito nets, insecticide spraying, reducing standing water (breeding grounds) in endemic areas
what is the first line of treatment for uncomplicated Plasmodium falciparum malaria?
Artemisinin (isolated from plant Artemisia annua)
what is the name of the malaria vaccine?
TRICK QUESTION: there isn’t one, but one is very much needed!
this parasitic infection is a major cause of adult-onset seizures in developing parts of the world. What is?
cysticercosis tissue infection caused by tapeworm Taenia Solium
how is cysticercosis contracted?
ingesting the eggs of tapeworm Taenia Solium - eggs form cysts in brain, muscles, eyes, other tissues
what is the animal host of Taenia (T) Solium?
pigs - transmitted via fecal oral route
