Protozoa & helminths Flashcards
What are symptoms of entamoeba/amebiasis?
can be asymptomatic, or Intestinal = bloody diarrhea, abdominal pain, colitis, fever
2-4 week incubation period
What is the cause of the most severe intestinal destruction of entamoeba/amebiasis?
E. histolytica
What can severe entamoeba/amebiasis look like?
extraintestinal amebiasis and abscesses –> spreading to liver with hepatomegaly, RUQ pain, weight loss, high fever
What can progress to necrotizing colitis with intestinal perforation and mucosal sloughing?
entamoeba/amebiasis
40% mortality rate
What are some risks of entamoeba/amebiasis?
tropical/subtropical crowding, poor sanitation, poor nutrition
How is entamoeba/amebiasis transmitted?
Ingestion of cysts, fecal-oral, person-person, human excrement, flies
How do you diagnose intestinal entamoeba/amebiasis?
- stool microscopy
- stool antigen testing
- stool PCR**
How do you diagnose entamoeba/amebiasis hepatic abscesses?
US, CT, MRI; anti-amebic antibodies in serum
elevated liver enzymes
How do you treat entamoeba/amebiasis?
metronidazole or tinidazole + luminal agent (diloxanide, iodoquinol, paromomycin)
alternate = tetracycline + chloroquine
surgical aspiration of hepatic abscesses
What is Naegleria Fowleri?
free living amoeba common in lakes and heated swimming pools, soil, sewers, tap water
What causes primary amebic meningoencephalitis and subsequent CNS infection?
Naegleria Fowleri
What are symptoms of Naegleria Fowleri?
5 day incubation and rapidly fatal
* early: headache, fever, stiff neck, lethargy
* 1-2 days later: photophobia, palsies of 3, 4, 6 nerves, N/V, behavioral abnormalities, seizures, AMS
* 7-10 days: coma and death
How can you diagnose Naegleria Fowleri?
elevated intracranial pressure
CSF: high WBC count, elevated protein, low glucose
motile trophozoites w/ centrifuged CSF wet mount
MRI: extensive edema and necrosis of front lobes
When should you consider diagnosis of Naegleria Fowleri?
w/ purulent meningitis w/o evidence on G staining, antigen detection assay, and culture relevant history
How do you treat Naegleria Fowleri?
They don’t really know, but it’s a combo of:
* amphotericin b
* rifampin
* fluconazole
* miltefosine
* azithromycin
* steroids
prognosis is poor
What is giarda?
Little flagella in upper small intestine that spreads through a trophozoite and cyst (infectious and can srvive a lot) – through fecal-oral, and water/food contamination
What’s the most common parasitic protozoan infection?
giarda
What are signs of giarda?
acute: profuse and watery, rarely bloody or mucus
50% - asymptomatic
chronic: abdominal cramping, bloating, flatus, malaise, anorexia
no fever or vomiting
Stools = greasy, frothy, foul smelling w/o blood, pus, or mucus
weight loss, malabsorption
What puts someone at risk for giarda?
Poor sanitation - young children, outbreaks in households, day care centers, residential facilities:
1) travelers to endemic areas
2) drinking from contaminated water during recreational wilderness travel
3) partners performing anal sex
4) impaired immunity
How do you diagnose giarda?
PCR stool assays
antigen stool assays
dx = wet mount of stool w/ mobile trophozoites or cysts
How do you treat giarda?
metronidazole, tinidazole
Paromomycin = safe in pregnancy
How do you prevent giarda?
water must be filtered, boil water for 1 minute, disposal of diapers/good hand hygiene
What predisposes you to malaria?
history of travel to endemic areas like the tropics, South/Central America, Middle East, India, Southeast Asia and Africa
young children, pregnant patients, travelers w/o exposure
What’s the most severe strain of malaria?
P falciparum with 24-48 hr cyclces
What are signs and symptoms of malaria?
acute headache and fatigue to irregular paroxysms and cycles of fever and sweats
then, myalgia, arthralgia, cough, chest pain, abdominal pain, anorexia, N/V/D
What cycles do the malaria bugs p vivax and ovale have?
48 hour cycles (tertian)
What cycle does p malariae have?
72 hr cycles (Quartan)
What do convulsions mean in malaria?
CNS progression
What will you see in a PE on a malaria patient?
anemia, jaundice, hepatomegaly, splenomegaly
How do you treat non-falciparum malaria?
chloroquine
How do you treat p vivax or p ovale malaria?
chloroquine and primaquine (check for G6PD deficiency!)
How do you treat uncomplicated p falciparum malaria?
combo:
arthemer-lumefantrin (US)
artesunate-amodiaquine (Africa)
How do you treat severe malaria?
admission
IV/IM artesunate
or
IV quinine or quinidine, oral ACTs, rectal meds
What are signs of severe malaria?
signs of severe illness, organ dysfunction, high parasite load
neuro: alteration of consciousness, seizures, coma
Severe anemia, hypotension/shock, noncardiogenic pulm edema/ARDS AKI, hypoglycemia, acidosis, hemolysis w/ jaundice, hepatic dysfunction, retinal hemorrhages, bleeding abnormalities, 2ndary bacterial infections
How do you diagnose severe malaria?
Giemsa-stained blood smears-repeat 8-24 hr intervals
Rapid antigen test = can have false negative
What chemoprophylaxis can you offer for malaria?
- chloroquine
- malarone
- mefloquine
- doxycycline
What are the four types of toxoplasmosis?
1) asymptomatic, mild febrile illness –> dormant until immunocomp
2) congenital
3) retinnochorditis
4) immunocomp
What does regular toxoplasmosis start out as?
1-2 weeks –> mild fever, fatigue, non-tender lymphadenopathy w/ headache, sore throat, rash, mylagias, hepatosplenomegaly
What is retinochoroiditis toxoplasmosis?
weeks to years after congenital
- affecting retina and choroid of eye – most commonly late presentation
- in teens, young adults
- eye pain, photophobia, vision changes, w/o systemic symptoms
In who is immunocompromised toxoplasmosis common?
reactivation in AIDs, cancer patients, immunosuppression, drugs
Risk of encephalitis w/ multiple necrotizing brain lesions
How can you diagnose toxoplasmosis?
IgM and/or IgG
PCR available, but not reliable
tachyzoites and/or cysts in histopathologic examination
WITH encephalitis: CT or MRI ring enhancing lesions
In what is toxoplasmosis common?
CATS
How do you treat toxoplasmosis?
No treatment necessary unless pregnant, severe, or affects vision:
- pyrimethamine + sulfadiazine w/ folinic acid
- OR clindamycin and TMP/SMZ
monitor WBC and platelets weekly
What do you use in 1st trimester pregnancy for toxoplasmosis instead of pyrimethamine?
use spiramycin instead (but must treat baby too)
What are signs of congenital toxoplasmosis?
fever, hypothermia, jaundice, V/D, hepatosplenomegaly, pneumonitis, myocarditis, thrombocytopenia, anemia, blueberry muffin rash
chorioretinitis, hydrocephalus, intracranial calcifications
What does congenital toxoplasmosis cause?
spontaneous abortion, stillbirths, severe neonatal disease, neuro manifestations, chorioretinitis (MCS), seizures, psychomotor retardation, deafness, hydrocephalus
What are symptoms of trichomoniasis?
male - nongonoccal urethritis, discharge
female - vaginitis w/ copious discharge and itching, dysuria, dyspareunia, abdominal pain
What would you see on a PE of trichomoniasis?
copious discharge, malodorous, frothy, yellow-green color, punctate hemorrhages “strawberry cervix”
How do you diagnose trichomoniasis?
wet mount – motile organism POC antigen and nucleic acid amplification asays
How do you treat trichomoniasis?
metronidazole or tinidazole
What are the signs of hookworm (roundworm)?
“ground itch” pruritic, maculopapular at skin penetration –> serpinigous tracks
THEN
dry cough, wheezing, low fever w/ larvae migration in lungs
1 month later: epigastric pain, diarrhea, anorexia –> anemia and protein malnutrition (pallor, weakness, dyspnea, heart failure, hypoalbuminemia, edema, ascites)
Where is hookworm (roundworm)?
most tropical and subtropical areas
What’s hookworm (roundworm) caused by?
ancylostoma duodenale and necator americanus that developed in soil –> penetrates skin –> migrates to body
How do you diagnose hookworm (roundworm)?
eggs in feces - Ova and parasite test
CBC - microcytic anemia, eosinophilia, hypoalbuminemia
occult blood in stool
How do you treat hookworm (round worm)?
Alebndazole single dose or mebendazole
pyrantel pamoate
iron supplements for anemia, blood transfusion
endemic = mass treatment of children
What type of bacteria can carry a tapeworm (cestode) and is found in beef/pork?
taenia saginata & solium
What type of bacteria can carry a tapeworm (cestode) and is found in fish?
diphyllobothrium latum
What type of bacteria can carry a tapeworm (cestode) and is found in dwarf?
hymenolepis nana
What are symptoms of a cestode of taeniasis?
asymptomatic or nausea, anorexia, epigastric pain, anxiety, headache, dizziness, urticaria
What are the symptoms of a cestode of diphyllobothriasis?
asymptomatic or fatigue, diarrhea, numbness, dizziness, allergic symptoms
megaloblastic anemia, B12 deficiency, is key here
What are the key symptoms of a cestode of hymenolepiasis?
asymptomatic or crampy abdominal pain, diarrhea, anorexia, weight loss, fatigue, pruritus ani
anemia, dizziness, irritability, sleep disturbances, seizures, and jaundice
How do you diagnose cestodes?
Eggs or proglottids in stool (ova or parasite stool)
Usually need 2-3 specimens
May have eosinophilia
B12 deficiency for diphyllobothriasis
What is the treatment for cestodes?
noninvasive = single dose praziquantel
alternative = nicolsamide
What’s the treatment for dwarf cestodes?
increased dose = praziquantel
repeat dose after 1 week
re-examine stool to check
What are the two types of invasive cestode/cysticercosis?
Neurocystericercosis and extraneural
What characterizes neurocystericercosis?
- seizures, neuro deficits, altered cogniton, psych disease
- intracerebral, subarachnoid, spinal cord lesions, intraventricular cysts
- ocular lesions years before symptoms start
What characterizes extraneural cysticercosis?
- asymptomatic nodules, with discomfort when inflamed
- MC include muscle/subq tissue involvement
What causes invasive cestodes?
T. solium
direct human-fecal contamination
How do you diagnose invasive cestodes?
- Neuroimaging
- CT & MRI: multiple parenchymal cysts, calcification
- ELISA and immunoblot assays
- brain biopsy
- excisional biopsy of skin or muscle lesion
How do you treat neurocysticercosis?
albendazole, praziquantel, adjunctive corticosteroids
When should antiparasitic therapy not be administered to treat neurocysticercosis?
- untreated hydrocephalus
- high cyst burden w/ diffuse cerebral edema
- presence of calcififed lesions
How do you treat extraneural invasive cestodes?
NSAIDs, excision for symptomatic solitary lesions
What is echinococcosis (tapeworm)?
large cystic lesions in liver or lung (any organ)
asymptomatic, often found incidentally
cysts can rupture = severe allergic reaction w/ fever & hypotension
may have = abdominal pain, chest pain, biliary obstruction, cholangitis, portal hypertension, cirrhosis, bronchial obstruction
What causes echinococcosis?
canine feces w/ parasite eggs, granulosus and multicularis
How do you diagnose echinococcosis?
imaging: US or CT - large cyst w/ daughter cysts
IgG ELISA assay - most sensitive confirmatory
How can you treat echinococcosis?
long course of albendazole
What indicates enterobiasis (pinworm)?
nighttime perianal itching
insomnia, restlessness, enuresis, impetigo, abdominal pain, nausea, vomiting
How do you diagnose enterobiasis?
worms found on skin, NOT on stool
“Tape test” – microscopic exam, best done at night right before bathing and in the morning
repeat over 3 days
How do you treat enterobiasis?
albendazole, mebendazole
pyrantel pamoate 1 dose
wash all bedding!
