Infectious DIsease Lab
Terms in this set (95)
malaria life cycle
anopheles mosquito injects malaria parasites into the blood. first, the plasmodium go to the liver. then they burst out of the liver shcizont and infect RBCs. main form is the ring form, looks like cytoplasm encircled.
asexual reproduction. formation of schizont-->bursts-->reinfects. bursting = anemia, bilirubin increasing. gametocytes can be taken up by another mosquito, mature in the mosquito, and pass on.
what type of parasite is malaria
what tests should be done for malaria
thick and thin smears are both important. thick is advantageous to identify smaller amounts of parasites.
banana shaped gametocyte
which malaria species do you only see the early trophozoites.
ring forms common in plasmodium falciparum. often can see multiple parasites in an RBC. do not see more mature forms.
when the plasmodium falciparum is stick on the outside/at the edge of the RBC.
what type of RBC does p. falciparum infect?
infects ALL RBCs.
which malaria types infect reticulocytes?
vivax and ovale. reticulocytes are larger than RBCs.
what is characteristic of vivax
schuffners dots inside of RBC (pigment). Also, the ameboid-shaped trophozoite is unique. usually will only see 1 parasite per RBC.
what is characteristic of P. ovale
see OVAL RBCs with schuffner's dots. the oval RBC is fimbriated with irregular margins.
these only infect reticulocytes.
characteristic of p. malariae
BAND FORM. only infects old RBCs, so they will appear the same size as falciparum cells that are infected.
schizont form present in....
all but falciparum. do not see more mature forms here.
chronic liver phases in malaria occur in....
plasmodium ovale and vivax
what do babesia and malaria have in common
both infect RBCs
how are babesia and malaria different?
babesia comes from a tick, and malaria from a mosquito.
babesia may have multiple chromatin dots/masses sometimes connected by thin cytoplasmic strands.
there are NO schizonts or gametocytes seen in babesia. when the trophozoite forms 2-4 merozites, the RBC ruptures.
can see SOME extra-erythrocytic parasites (rare).
tetrad of merozoites. Babesia. not commonly seen.
which intestinal sporozoa can cause diarrhea?
how are intestinal sporozoa stained
acid fast stain. exception: microsporidia can be identified with a trichrome stain because of its size.
pathogenensis of intestinal sporozoa
sit on intestinal tract and cause inflammation, and invade epithelial cells--> chronic diarrhea.
more commonly in HIV patients. they get severe diarrhea.
all spread via fecal-oral route.
which intestinal sporozoa is 1-2 µm in diameter?
which intestinal sporozoa is 4-7µm in diameter?
which intestinal sporozoa is 8-10µm?
which intestinal sporozoa is 20-30 µm long and 10-19µm wide?
isospora aka cystoisospora
causes chronic diarrhea. can also disseminate to other organs.
use trichrome stain for stool specimens. really small.
which intestinal sporozoa is most common in HIV patients?
where do most people get cryptosporidium
swimming pools, water parks. mainly get it from CONTAMINATED WATER.
also get it from daycare, food, pets/farm animals.
acid fast stain on stool specimen. also can use modified for more intense red color.
albendazole! even though not a helminth
no good therapy in HIV patients.
otherwwise, nitazoxanide, paromycin.
how do people get cyclospora?
consuming contaminated FRUITS and VEGETABLES or contaminated water. specifically, berries and basil!
how do you diagnose cyclospora
acid fast stain on stool
acid-fast stain on stool. HUGE!!!!
because these are so large, also will be able to see them in a wet preparation.
characteristic appearance with circle and outer oval appearance.
what can you also stain intestinal sporozoa with?
what forms can you find toxoplasma in tissue?
tachyzoites (crescent-shaped) and bradyzoites (cysts).
either can be found in the brain tissue.
the cysts can burst and release the multiple parasites within it to infect more tissues.
what kind of parasite is toxoplasma?
what is the most common cause of CNS infection in HIV patients?
toxoplasmosis. usually occurs when CD4 counts are less than 100.
how do people get toxoplasmosis?
often from eating undercooked meat, or dealing with cat litter.
reactivation of previous infections also possible.
who is infected with pneumocystis cysts
most often seen in HIV patients with CD4<200.
what does PCP cause
what is PCP?
how is PCP stained?
GMS stain = silver stain. stains the cysts wall.
toluidine blue stain also works.
giemsa stains intracystic bodie and not the wall.
how does PCP appear on a stain?
cysts are intact or can rupture and look collapsed.
characteristic CUP shape.
free trophozoite form. little pink dots. each little thing is a trophozoite coming together to be a big clump of stuff. both forms are present in samples.
trichomonas trophozoites movement
motile on a wet mount. jerky, non-directional movement. see flagella and you see it around larger epithelial cells. often not stained because would kill the cell and then would not see movement.
what does trichomonas cause?
urogenital, vaginitis, vaginal discharge. strawberry cervix with green foul smelling discharge.
what free-living ameba is found in VERY warm fresh water such as ponds and lakes?
Naegleria fowleri (think nalgene and water).
when you dive into the water, these amebae invade via the nose and can go to the brain.
prognosis of naegleria fowleri
fulminant. most people die within 1-2 weeks. only one known survivor in US.
causes amebic meningoencephalitis.
naegleria fowleri DX:
trophozoites in brain tissue or CSF.
naegleria fowleri RX:
usually die before diagnosis is made.
naegleria fowleri SX:
stiff neck - suggests meningitis. meningitis and encephalitis.
people come in with fever, severe headache, vomiting after swimming in a local pond.
what does acanthaomoeba cause?
can cause amebic ketatitis = inflammation of the cornea. this is the most common infection.
you can also get encephalitis *granulomatous.
where can you find acanthaomoeba?
free-living in nature in fresh water or other places. also can be in contaminated contact lens solution.
headache, fever, seizures, focal neurologic signs. in cyst and trophozoite stage. may also infect cornea --> can lead to blindness.
treatment of acanthamoeba
topical agents. if fails, may need enucleation or corneal transplant.
free-living in nature.
what can balamuthia cause?
encephalitis. gets into nose and goes to brain.
see trophozoites in cysts or brain.
most asymptomatic. can develop diarrhea and abdominal pain.
rx: metronidazole, doxy.
amebae. can be nonpathogenic but causes diarrhea
treat with metronidazole
not pathogenic, but need to distinguish these from entamoeba histolytica.
only ciliate and causes COLITIS. so large, bigger than isospora.
treat with tetracycline.
loa loa. wuchereria bancrofti. both huge. much larger than RBCs. can be seen using giemsa stains.
bacteria spirochete. includes lyme and syphilis. causes relapsing fever. in log cabins and in the west. ONLY SPIROCHETE you will see int he blood.
where do you get wucheria bancrofti and bruga malayi?
what is the vector for wuchereria?
disease caused by wuchereria
adult worms live in lymphatics --> lymphedema because blocking the lymph and fluid backs up. leads to elephantiasis.
giemsa stained blood smear.
also can find their babies in the blood - microfilaria.
doxycycline and diethylcarbamazine
where do you get loa loa
vector of loa loa
chrysops biting fly.
loa loa life cycle and disease
adult worms live in subQ tissue. CALABAR swellings= causing swelling wherever it migrates. can migrate ACROSS EYE!! does not cause blindness.
adults release microfilaria into the blood during the day. can find these microfilaria in the blood during the daytime.
DEC. remove adult worm if in eye
onchocerca volvulus location
africa and south/central america
vector onchocerca volvulus
simulium black fly
adult worms live in nodules in skin - onchocercomas. adults release microfilaria into the eyes. when the microfilaria migrate across the eye can lead to blindness = river blindness=seeing black (transmitted by BLACK fly).
blindness occurs if near the head. near extremities? microfilaria moving through skin and causes extreme itchiness and eosinophilia. get leopard skin whit white dots.
biopsy. find microfiliar.
slit lamp exam - microfilaria in the eye.
remove skin nodules. ivermectin every 6-12 mos. give doxy as well.
prophylaxis in africa because so debilitating.
how do you get trichinella spiralis?
eating undercookd meat. these larvae can be found in muscle in animals. these larvae, when consumed, will invade GI tract then go to blood and spread to muscles.
cardinal symptoms trichinella spiralis
fever, marked eosinophilia, muscle pain, periorbital edema.
trichinella spiralis dx and rx
dx: serum antibody, muscle biopsy
rx: albendazole, mebendazole.
how do you get diphyllobothrium latum
eating undercooked fish.
one of the largest tapeworms (20-30 feet). most common in cold bodies of water.
disease leads to b12 deficiency. this may be due to consumption by tapeworm.
dx: eggs in stool. as it grows, it releases pieces of its tail in the stool.
get it from undercooked freshwater fish. china, japan, korea, vietnam
trematode. worms migrate in biliary tract. goes form the stomach to the duodeneum which is near the gall bladder and liver. than it goes into the biliary tract nad blocks it. now blocking secretions from gall bladder and can no longer digest fats. become jaundices, and can lead to bile duct cancer.
sheep liver fluke. found in sheep raising areas. acquired by eating contaminated watercress.
adult worms live in the bile duct. can block this and cause hepatitis.
lung fluke. acquired by eating undercooked freshwater crabs and crayfish. adult worms live in the lung --> causes lung cavity and bloody sputum. see the eggs in sputum.
what is scabies caused by
mites. sarcoptes scabiei.
adult mites enter skin and create c-shaped burrows (serpiginous). female mites lay eggs in the skin burrows. most commonly see these burrow in finger web spaces, wrists, sides of hands, feet, penis, buttocks. causes intense itching.
people tend to itch A LOT. sometimes so much that it is hard to see the actual burrow.
is scabies contagious?
HIGHLY. transmitted by direct contact.
see characteristic lesions - burrows.
can do skin scraping. best to do at end of fresh burrow. look for mites and eggs.
ivermectin if topical permethrin cream does not work.
norweigan scabies. occurs in immunosuppressed patients. can have extensive scaling and crusting. thousands of mites present in the epidermis. highly highly highly contagious.