Mites, Protozoa, Tapeworms, Fungi, Tick-borne Bacteria

Question 1

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?

Answer 1

scabies burrow (by arthropod Sarcoptes scabiei)

Question 2

what causes scabies?

Answer 2

arthropod Sarcoptes scabiei

Question 3

how is scabies spread?

Answer 3

direct skin contact, outbreaks more likely in overcrowded or institutional settings

Question 4

scabies mites mate on the skin surface, then the female secretes proteolytic enzymes to burrow under the ____ layer of the epidermis

Answer 4

stratum corneum (outermost layer)

Question 5

in response to scabies infection, the immune system mounts a type __ hypersensitivity reaction

Answer 5

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

Question 6

patients with scabies infection typically don’t develop itching until 3-6 weeks later. Why is this?

Answer 6

immune system mounts Type IV hypersensitivity reaction, which is cell mediated and therefore delayed

Question 7

what is the treatment for scabies?

Answer 7

topical cream (permethrin) which is spread over whole body and left on for 8 hours, then repeated 2 weeks later

Question 8

what goes wrong in crusted scabies?

Answer 8

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

Question 9

pruritic means

Answer 9

itchy

Question 10

Plasmodium parasites cause what kind of disease in humans?

Answer 10

malarial disease

Question 11

What is the most common form of malaria, and also one of the most deadly?

Answer 11

Falciparum malaria (from Plasmodium falciparum)

Question 12

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?

Answer 12

malaria

Question 13

what is the primary host for Plasmodium falciparum, which causes malaria in humans? (be specific)

Answer 13

Anopheles mosquito

Question 14

when female mosquitos draw human blood and transfer Plasmodium parasite, what form is it in?

Answer 14

sporozoite

Question 15

when Plasmodium parasite begins to colonize hepatocytes, what form/phase is it in?

Answer 15

schizont phase - replicate inside hepatocytes, forming merozoites

Question 16

after replicating inside hepatocytes, Plasmodium parasites are in what stage of life cycle?

Answer 16

merozoites/merosomes - these can travel through bloodstream undetected because they are covered in liver cell membrane

Question 17

place the life cycle of Plasmodium parasites in order:
schizont
merozoite/merosome
trophozoite
sporozoite

Answer 17

1. sporozoite - motile, immature
2. schizont - mature, in liver
3. merozoites - travel through blood undetected, covered by liver cell membrane
4. trophozoite - inside RBC, characteristic ring shape

Question 18

what are the 2 ways in which Plasmodium parasite (causing malaria) is amplified in host body?

Answer 18

exoerythrocytic phase - inside hepatocytes

erythrocytic phase - inside RBC

Question 19

3 ways to prevent malaria infection

Answer 19

mosquito nets, insecticide spraying, reducing standing water (breeding grounds) in endemic areas

Question 20

what is the first line of treatment for uncomplicated Plasmodium falciparum malaria?

Answer 20

Artemisinin (isolated from plant Artemisia annua)

Question 21

what is the name of the malaria vaccine?

Answer 21

TRICK QUESTION: there isn’t one, but one is very much needed!

Question 22

this parasitic infection is a major cause of adult-onset seizures in developing parts of the world. What is?

Answer 22

cysticercosis tissue infection caused by tapeworm Taenia Solium

Question 23

how is cysticercosis contracted?

Answer 23

ingesting the eggs of tapeworm Taenia Solium - eggs form cysts in brain, muscles, eyes, other tissues

Question 24

what is the animal host of Taenia (T) Solium?

Answer 24

pigs - transmitted via fecal oral route

Question 25

taeniasis

Answer 25

growth of tapeworms in intestines (by Taenia Solium)

Question 26

how can autoinfection of cysticercosis happen?

Answer 26

someone with taeniasis (Taenia Solium tapeworms) ingest eggs of their own worms

Question 27

complete this sentence: regarding Taenia Solium infection (cysticercosis), if you eat a ____, you get a worm. If you eat an egg, you get a ____.

Answer 27

eat a cyst, get a worm (tapeworm in intestine)

eat an egg, get a cyst (larval cysts grow in tissues)

Question 28

T/F: Taenia Solium larval cysts cause symptoms once they have enlarged in host tissues

Answer 28

FALSE: clinical problems begin when larval cysts die of old age - triggers inflammatory response

Question 29

what types of WBC are heavily involved in parasitic invasions?

Answer 29

eosinophils - high counts seen with parasitic and fungal infections, allergies, skin disorders, autoimmune disorders, and some blood cancers

Question 30

pt presents to ER with abdominal pain, anorexia, weight loss, and upset stomach. They have recently travelled to Latin America for a missionary trip. MRI reveals cysts in their brain tissue, as well as leg muscle, where an X-ray was taken for a possibly fractured leg. What do you suspect?

Answer 30

taeniasis (and neurocysticercosis) by Taenia Solium (tapeworm) infection (ingested eggs of T Solium)

Question 31

definitive host

Answer 31

aka primary host, where parasite reaches maturity and sexual reproduction takes places

Question 32

do parasites undergo sexual reproduction in intermediate hosts?

Answer 32

typically not

Question 33

Albendazole is what kind of drug (treats what?)

Answer 33

anthelminthic - treats tapeworm infections