lesson six Flashcards
1
Q
protozoa
A
- parasite
- one-celled eukaryotes
2
Q
metazoa
A
- parasite
- multicellular animals
3
Q
ectoparasites
A
- free living bugs
4
Q
protozoa
A
- some have a cyst form with a tough protective layer outside of the cytoplasmic membrane
- growing form in many species called trophozoite (no cell wall)
- cyst form may also be called an oocyst
5
Q
protozoan: entamoeba histolytica
A
- agent of amoebic dysentery
- primary food: RBC (ulcer formation and bloody diarrhea)
- both trophozoite and cysts form
- cysts high degree of resistance to chlorine
- can be treated with nitroimidazole
6
Q
protozoan: giardia lamblia
A
- flagellate; causative agent of giardiasis (bever fever)
- intestinal upsets, flatulence, nausea, abdominal cramps, diarrhea
- cyst and trophozoite
- cysts high resistance to chlorine
- treated with nitroimidazoles
7
Q
protozoan: trichomonas vaginalis
A
- flagellate, mobile
- no cyst stage, person to person infection- sexual transmission
- found in vagina and male urethra
- intense itching, inflammation of tissues
- treated with nitroamidozoles
8
Q
protozoan: acanthamoeba sp
A
- grows in water, exists as cyst form in dust
- important for contact lens wearers
- eye loss outcome of infection
- cysts and trophozoite stage in humans
9
Q
protozoan: cryptosporidium parvum
A
- cows, rats, dogs, cats, to people
- chronic diarrhea, sever in immunocompromised
- must us ZN stain
oocysts have high resistance to chlorine - no good treatment
10
Q
protozoan: toxoplasma gondii
A
- cat feces contain oocysts
- tissue cysts containing the protozoan can form in other animals
- acquired from undercooked meat or from contact with cat feces
- serious for fetes in pregnancy (first trimester)
11
Q
protozoan: trypansoma
A
- blood parasites, transmission mostly vectors
1. T. brucei gambiense causes african sleeping sickness (africa-tsetse fly)
2. T. cruzi causes chaga’s disease in south america (kissing bug)
12
Q
protozoan: leishmania sp.
A
- 20 different species, all transmitted by sand fly vector
- visceral, cutaneous and mucocutaneous syndromes
live and develop in macrophages
13
Q
protozoan: plasmodium sp.
A
- cause of malaria
- 4 main types, all transmitted by anopheles
- most dangerous is p. falciparum (infects all ages of RBC)
- mosquito carries the sprozoite in saliva, this enters the blood stream, then liver cells within 30 min
14
Q
symptoms of falciparum malaria
A
-fever and chills caused by release of toxic
breakdown products when the RBCs rupture and
release developing parasites
-sequestration (sticky collections) of parasites
and red blood cells occlude capillaries causing
organ death. This is due to a virulence factor
called PfEMP1
15
Q
severe consequences of p. falciparum malaria
A
- cerebral malaria: clumping and occlusion of blood vessels
- anemia: caused by lysis of RBC
- kidney failure: caused by high levels of hemoglobin breakdown products
16
Q
worms=metazoa
A
- nematodes: intestinal and blood
- trematodes
- cestodes
17
Q
metazoa: nematodes
A
- roundworms with complete digestive system
- two categories
a) eggs are the infective stage
b) larva are the infective stage
18
Q
nematodes: enterobius vermicularis (pinworm)
A
- eggs are the infective stage
- spends whole life cycle in human
- live in large intestine, females migrate to anus
produces a glue to stick eggs to the skin - transmitted by direct contact with eggs or ingestion of eggs stirred up in dust
19
Q
nematodes: ascaris lumbricoides
A
- large round worms
- live in intestine of pigs, cows, horses
- eggs in soil very hardy (thick protein coat)
infection by eggs - diagnosis of infection by examination of feces
20
Q
nematodes: hookworms
A
- larvae as infectious stage
- enter intact skin of bare feet
- →lymph & circulatory system,
→ lungs, → coughed up and
swallowed down to the small
intestine, where they attach by
hooks on the scolex - cause anemia
- only found in warm climates
21
Q
nematodes: anisakis
A
- accidentally infect humans in larval form
- fish nematodes
- rare type of infection
- prevention: heat or blast freeze, cleaning of fish asap
22
Q
nematodes: trichinella spiralis
A
- larvae infectious
- ingestion of encysted larvae in undercooked pork, boar, bear, walrus
- larvae encyst in striated muscle fibers
- muscle weakness is a dominant symptom
23
Q
blood nematodes (filaria)
A
- lymphatic filariasis: adult worms live in lymph tissue
- onchocerciases: adult worms live in subcutaneous tissue
- microfilariae: (offspring) circulate through bloodstream or migrate through subcutaneous tissue
- transmission by mosquitoes
24
Q
trematodes: schistosoma
A
- human is infected by cercarae that penetrate intact skin in fresh water ponds
- adult worms hide from host immune system under a
coat of protein acquired from the host - worms reside in the venous plexus of bladder or
intestine, depending on species. - eggs cause inflammation
25
Q
schistosoma: s. haematobium
A
urinary schistosomiasis (bilharzia)
-results in inflammation of bladder wall, chronic sequalae- cancer
- Africa, Middle East
26
Q
schistosoma: s.japonicum
A
- intestinal parasite
- found in far east
27
Q
schistosoma: s. mansoni
A
- intestinal parasite
- found in africa, SA, caribbean
over 250 million people infected
28
Q
swimmers itch
A
- Caused by a duck
schistosome - These cercariae do not
enter the human
circulation, self-limiting,
causes skin itching due to
the immune response
29
Q
c. cestodes (tapeworms)
A
- intestinal parasites, dependent on host for nutrients, no digestive system
- head, or “scolex” has suckers or hooks for attachment to gastric mucosa
- body consists of segments called proglottids, each of which contains male and female reproductive organs
- acquired by eating inadequately cooked contaminated beef, pork or fish
30
Q
tapeworms cause two types of disease
A
- intestinal infection: mild, produced by pork, beef, fish or rodent
- deep tissue infection: serious, pork or dog tapeworm
31
Q
c. cestodes: taenia saginata
A
- beef tapeworm
life cycles requires both human and cattle - infectious tissue larvae ingested by humans in infested meat
- eggs passed in feces
- mild symptoms
32
Q
c. cestodes: taenia solium
A
- pork tapeworm
- intermediate host is pig
- cerebral cysts cause cysticercosis
- person to person transmission
2 modes of infection: - eggs: hatching in intestine then escape and penetrate body tissues
- larvae: result in adult worm in intestine
33
Q
c. cestodes: echinococcus granulosus
A
- dog tapeworm
- small, humans are dead end hosts
- larva develops into hydatid cyst with hundreds of worm parts but cannot form a whole tapeworm in humans
34
Q
ectoparasites
A
- live on skin
- do not enter deep tissues
- secondary infections due to scratching
35
Q
ectoparasites: scabies
A
- mites burrow into skin, feed, life span 30 days, mate, lay eggs
- host defenses cause inflammation and itching
- elbows, fingers, breasts, groin, buttocks
36
Q
ectoparasites: lice or crabs
A
- surface dwellers
- penetrate skin with mouth, suck blood
- female glues eggs to hair shafts
- eggs hatch in 5-10 days
- secondary infections when lice feces are crushed into wounds
