Protozoal infections Flashcards
protozoa causing bloody diarrhea
- Entamoeba
- Balantidium
symptoms caused by entamoeba histolytic
- bloody diarrhea
- ulcers
- liver abscesses
epidemiology of entamoeba
- associated with camping/hikers
- fecal oral transmission - cysts are passed in stool
lifecycle of entamoeba
- only cyst form is infectious
- ingest cyst, stomach acid erodes cyst leading to growth and invasion
- trophozoites are the actively replicating form and indicates parasitic infection
pathogenesis of entamoeba
- gastric acid stimulates excystation
- local necrosis of large intestine
- destruction of epithelial cells
clinical disease of entamoeba
- ab pain and cramps, colitis, bloody diarrhea
- weight loss and anorexia
- liver abscess - flask shaped ulcer, fever, RUQ pain, tenderness
treatment of entamoeba
- non-invasive: paramomycin
- invasive: metronidazole followed by paramomycin
MOA of metronidazole
- destabilizes DNA
epidemiology of balantidium coli
- ciliate: only spp that infects humans
- fecal oral transmission
- pigs are reservoirs
- infection from ingested cysts
clinical disease of balantidium coli
- watery diarrhea WITH blood and pus
- ab pain, nausea, anorexia
- secondary bacterial infections of GI mucosa
treatment for balantidium coli
- tetracycline
- metronidazole and iodoquinol are alternatives
epidemiology of giardia
- fecal oral via cysts
- beavers and muskrats are reservoirs
- more common in campers and hikers and also in daycares
- most often transmitted from contaminated water
clinical disease of giardia
- explosive watery diarrhea
- foul smelling stools
- ab cramps
- can progress to malabsorption syndrome - steatorrhea (foul smelling (malodorous), mushy, greasy stool)
diagnosis of giardia
- microscopic examination of stool
- bilobed nuclei, looks like a horseshoe crab
- has flagellum
- falling leaf motility
treatment and prevention of giardia
- treat with metronidazole
- boil water and treat carriers
- cysts can survive in chlorinated water
epidemiology of cryptosporidium
- mainly affects children (peak age around 5)
- can be severe in IC patients - lethal in AIDS, #1 cause of AIDS associated diarrhea
pathogenesis of cryptosporidium
- oocyst is infectious form
- stains acid fast
- resistant to chlorination
- water born disease
lifecycle of cryptosporidium
- infects intestinal epithelial cells
- oocyst is infectious and diagnostic form
clinical disease of cryptosporidium
- asymptomatic to severe disease
- self limited (1-2 wk) enterocolitis
- watery diarrhea, dehydration, weight loss, ab pain, fever, N/V
- in AIDS pts, can shit up to 50 times a day
diagnosis of cryptosporidium
- acid fast staining
- pink is positive and green is negative
treatment of cryptosporidium
- replace fluids and electrolytes
- nitazoxanide for immunoCOMPETENT patients
- HAART therapy for AIDS patients
epidemiology of isospora belli
- humans are only known reservoir
- more prevalent in AIDS pts
- outbreaks are commonly seen in day cares and mental institutions
- fecal oral: mature oocysts ingested and reside in epithelium
clinical disease of isospora belli
- mimics giardiasis with malabsorption syndrome
- steatorrhea
diagnosis of isospora belli
- oocyst found in feces is elliptical
- cryptosporidium is round
- microscopic examination of iodine-stained stool smears
triad for isospora belli diagnosis
- acid fast staining
- malabsorption
- watery diarrhea
treatment for isospora belli
- TMP-SMX
characteristics of cyclospora cayetanensis
- resembles cryptosporidium excepts infects immunoCOMPETENT patients
- explosive watery diarrhea
- fecal contaminated water or food (raspberries or basil)
clinical disease of cyclospora cayetanensis
- low grade fever, fatigue, anorexia, abdominal pain, N/V
diagnosis of cyclospora cayetanensis
- stains acid-fast
- fluoresces blue under UV light
treatment of cyclospora cayetanensis
- TMP-SMX
latin name for pinworms
- enterobius vermicularis
common name for enterobius vermicularis
- pinworm
transmission of enterobius vermicularis (pinworm)
- fecal oral
- eggs are “sticky”
- eggs can be transmitted on fomites
- autoinfection occurs
- common in children 5-9 years old
clinical disease of enterobius vermicularis (pinworm)
- intense perianal itching at night
- prickling pain
- diarrhea during acute infection
- migrating worms may get lost: vaginal itching and granuloma formation
diagnosis of enterobius vermicularis (pinworm)
- cellophane (scotch) tape method
- only used for this type of worm
treatment for enterobius vermicularis (pinworm)
- mebendazole
latin name for roundworms
- ascaris lumbricoides
common name for ascaris lumbricoides
- roundworm
transmission of ascaris lumbricoides (roundworm)
- fecal oral
- contaminated food or water
- eggs can survive for months
lifecycle of ascaris lumbricoides (roundworm)
- ingest egg
- egg hatches and travels to liver, heart, lungs, etc.
clinical disease for ascaris lumbricoides (roundworm)
- dependent on number of eggs
- few eggs - asymptomatic
- early phase: large migrate to lungs producing fever, nonproductive cough, dyspnea, wheezing
- late phase: diffuse or epigastric pain, N/V, bolus can obstruct and perforate bowel
- can be lethal
diagnosis of ascaris lumbricoides (roundworm)
- CBC may show eosinophilia
- sputum may show larvae
- eggs in stool: knobby coated, oval shaped, bile stained
treatment for ascaris lumbricoides (roundworm)
- albendazole
- if pregnant then use pyrantel pamoate
toxocariasis (roundworm)
- dog and cat roundworms
symptoms of toxocariasis (roundworm)
- larvae can penetrate any tissue: lungs, heart, liver, kidney, skeletal muscle, eyes, CNS is most common
- bleeding, necrosis, eosinophilic granulomas
diagnosis of toxocariasis
- eggs found in pet feces
- eggs NOT found in human feces
treatment for toxocariasis
- albendazole
latin name for whipworm
- trichuris trichiura
- transmission of trichuris trichiura (whipworm)
- fecal oral
- prevalent in southern appalachian range and gulf coast states
clinical disease of trichuris trichiura (whipworm)
- light infections (100): ab pain, vomiting, anorexia, weight loss, diarrhea (can be bloody), tenesmus, rectal prolapse
diagnosis of trichuris trichiura
- barrel (football) shaped eggs, plugged ends
- RBC and WBC present
treatment of trichuris trichiura
- albendazole
latin name for hookworms
- ancylostoma duodenale
- necator americanus
epidemiology of hookworms (N. americanus)
- penetrate into feet
- go to lymphatics, blood, heart, lungs, cough them up and then swallow into GI tract
early symptoms of hookworms (N. americanus)
- itching, localized maculopapular eruption on foot
- low grade fever
- mild cough, wheezing when worm in lungs
late symptoms of hookworms (N. americanus)
- N/V, diarrhea
- microcytic and hypochromic anemia
- fatigue and dyspnea
chronic disease of hookworms (N. americanus)
- emaciation, physical and mental retardation
diagnosis of hookworms (N. americanus)
- early infection: eosinophilia, normal stool
- patchy infiltrate on chest X-ray (migrating larvae)
- GI infection: non-bile stained, segmented eggs in stool
- iron deficiency anemia
treatment of hookworms
- abdendazole
- iron therapy for anemia
anclyostoma braziliense (hookworm)
- dog and cat hookworm
- humans are accidental hosts
clinical disease of anclyostoma braziliense
- cutaneous larval migrans: ground itch, creeping eruption
- Loeffler syndrome: pulmonary infiltrates with peripheral eosinophilia
- at risk: children (sandboxes), beaches
treatment for anclyostoma braziliense
- thiabendazole
worm infections where humans are accidental hosts
- toxocariasis: dog and cat roundworms
- anclyostoma brazilense: dog and cat hookworm
latin name for threadworm
- strongyloides stercoralis
common name for strongyloides stercoralis
- threadworm
clinical disease of strongyloides stercoralis (threadworm)
- pneumonitis similar to hookworm
- occur in IC patients
- diarrhea can be bloody, malabsorption
- symptoms like peptic ulcer, peripheral eosinophilia
chronic infection of strongyloides stercoralis (threadworm)
- hyperinfection syndrome: profound diarrhea, malabsorption, electrolyte imbalance, meningitis, secondary bacteremia
- seen in IC patients
diagnosis of strongyloides stercoralis (threadworm)
- Baermann funnel gauze method
treatment of strongyloies stercoralis (threadworm)
- ivermectin
reservoir of trichinella spiralis
- pork, undercooked bear meat
- larvae form found in striated muscle
clinical disease of trichinella spiralis
- acute stage: larvae invade tissue: fever, diffuse myalgias, eosinophilia, periorbital edema
- late stage: lethal when heart, brain and lungs infected
diagnosis of trichinella spiralis
- outbreak traced to infected pork or beat meat
- encysted larvae in meat or muscle biopsy
- pt presents with diffuse muscle pain- diffuse myalgias
- CBC - marked eosinophilia
treatment of trichinella spiralis
- albendazole
transmission of anisakis simplex
- roundworm of marine fish
- higher incidence where raw fish is eaten
clinical disease of anisakis simplex
- within hours after ingested of undercooked (raw) fish
- violent ab pain, N/V
- severe eosinophilic granulomatous response if larvae pass into bowel
- can mimic Crohns
hosts for all flukes
- all flukes have clam or snail intermediate hosts
characteristics of fluke eggs
- all flukes (and tapeworms) have operculated eggs
latin name for giant intestinal fluke
- fasciolopsis buski
common name for fasciolopsis buski
- giant intestinal fluke
epidemiology of giant intestinal fluke
- ingestion of contaminated water chestnuts
- look like leeches or tiny tadpoles
- travelers from china, vietnam, thailand, india, malaysia
clinical disease of giant intestinal fluke (fasciolopsis buski)
- diarrhea alternating with constipation
- malabsorption syndrome with malodorous, greasy stools
diagnosis of giant intestinal fluke
- large, bile stained, operculated eggs in stool
treatment of giant intestinal flukes (fasciolopsis buski)
- praziquantel
latin name for sheep liver fluke
- fasciola hepatica
transmission of sheep liver fluke
- infection from contaminated water plants
clinical disease of sheep liver fluke (fasciola hepatica)
- URQ pain, fever, chills, eosinophilia, hepatitis, biliary obstruction
treatment of fasciola hepatica
- bithionol
latin name for chinese liver fluke
- clonorchis sinensis
transmission of chinese liver fluke
- consumption of undercooked freshwater fish
clinical disease of clonorchis sinensis
- fever, diarrhea, epigastric pain, hepatomegaly, anorexia, jaundice
treatment of clonorchis sinensis
- praziquantel
3 main species of schistosomes
- Schistosoma haematobium (bladder): terminal spine
- S. japonicum (bowel)
- S. manosin (bowel): lateral spine
transmission of schistosomes
- penetrate skin when swimming, burrow in and cause itching (swimmers itch)
clinical disease of schistosomes
- acute (Katayama syndrome): swimmers itch, fever, chills, cough, urticaria, ab pain, diarrhea, eosinophilia
- chronic: granulomatous reactions and fibrosis, bloody diarrhea (S. mansoni mostly), associated with clay pipestem fibrosis around portal vein
diagnosis of schistosomes
- leukocytosis, eosinophilia, polyclonal gammopathy
- S. mansoni: egg larva is oval shape and curved anterior end with lateral spine, found in stool
- S. japonicum: smallest eggs, oval shaped, spine not distint, found in stool
- S. haematobium: terminal spine, large egg, found in urine
treatment of schistosomes
- praziquantel
general characteristics of cestodes (tapeworms)
- flat and ribbon like
- head has cup shaped suckers and hooks
- segmented bodies: proglottids
- eggs in feces are diagnostic
- all eggs are operculated
epidemiology, transmission, and clinical disease of Taenia solium (pork tapeworm)
- undercooked pork
- in larvae ingested in meat: mostly GI symptoms - ab discomfort, diarrhea, indigestion
- cystericercosis is dangerous - eggs ingested in contaminated water, vegetables
diagnosis of taenia solium
- proglottids and eggs in feces
- treatment of taenia solium
- praziquantel
symptoms of neurocystericercosis
- hydroencephalitis, mengitis, nerve damage, seizures, visual defects
diagnosis of neurocystericercosis
- imaging studies for calcified cysticeri
- (CT,MRI) - big calcified cysts seen on MRI
treatment for neurocystericercosis
- praziquantel, albendazole
- steroids, surgery
latin name for beef tapeworm
- taenia saginata
- does not cause neurocystericercosis in humans
- diagnosis and treatment identical to T. solium infection
latin name for fish tapeworm
- diphyllobothrium latum
transmission and reservoir of fish tapeworms
- undercooked freshwater fish
- wild animal reservoirs: bears, minks, walruses, canine
clinical disease of fish tapeworms
- most are asymptomatic
- associated with depleted serum vitamin B12
- megaloblastic anemia, neurological manifestations: painful tingling, fatigue, weakness, loss of coordination, confusion, weight loss
treatment of fish tapeworm
- niclosamide
- praziquantel alternative
- vitamin B12 supplementation
Echinococcus spp.
- tapeworms of carnivores in sheep-raising areas
- humans are intermediate hosts
clinical disease of echinococcus spp.
- hydatid cyst disease
- liver and lung where cysts develop: ab pain, hepatic mass, bile duct obstruction
- lungs: chest pain, cough, hemoptysis
- death from anaphylactic shock after rupture of cysts
diagnosis of echinococcus spp.
- CBC- eosinophilia
- X-rays for cysts in lungs, bone and muscle
treatment for echinococus
- surgery
- albendazole and mebendazole are DOCs
