Lec45 Enteric Protozoa Flashcards
What is entamoeba histolytica [amebiasis] transmission?
- fecal oral
- food/water contaminated with infective cysts
- oral-anal sexual contact
Where are majority of entamoeba infetions? who is at risk?
in developing countries
at risk: recent immigrants, MSM
What does trichomonas vaginalis cause?
parasite UTI
What is life cycle of entamoeba?
- two stage life cycle
- –> infective cyst
- –> multiplying trophozoite
- ingest cyst form
- see trophozoite form in biopsies, both passed in feces
What are clinical signs of entamoeba?
- may have just normal diarrhea, little symptoms
- amebic dysentery = stool with blood, mucous, pus
- amebic colitis = flask shaped ulcer
travels systemically in <1%:
- amebic liver abscess= anchovy paste aspirate, often do not show trophozoites in aspirate, use serology
- pulmonary abscess/pleural effusion
- brain abscess
What is treatment of choice for entamoeba histolytica?
- metronidazole [or tinidazole because fewer side effects]
= + iodoquinol to kill cysts
What is mech of action metronidazole?
upsets electron balance within paraste
What do you use to kill entamoeba cysts?
iodoquinol
how do you diagnose entamoeba?
- serology
- parasite cyst in stool
What is balamuthia? route of infection?
- free living amoeba
- transmit = direct innoculation into nares
What are clinical brain complications of balmuthia?
- progressive meningoencephalitis that does not usually respond to therapy
What are the 3 types of free living amoeba?
- acanthamoeba species
- balamuthia mandrillaris
- naegleria fowleri
How do you distinguish between parasitic amoeba and free living amoeba?
- free living almost invariably kill hosts
- not dependent on host for transmission
- no host to host trans
How are free living amoeba present in environment?
- as trophozoites or cysts
How is free living amoeba transmitted?
- no person to person transmission
- acquired by direct inoculation or inhalation of cysts
- via nares or skin
What does naegleria encephalitis cause? spread?
- primary amoebic encephalitits
- direct innoculation in fresh water
What does acanthamoeba cause? spread?
- acanthamoeba meningoencephalititis
- infection associated with contact lens = severe keratitis
- direct innoculation in fresh water through nasal passage or broken skin
only need to ingest < 10 cysts
What is source of giardia lamblia?
- ingest cysts in contaminated water/food/fecal-oral contact
What are signs of giardia lamblia?
- 25% asymptomatic
- diarrhea, cramps, bloating, nausea
- may be constant or intermittent, last wks
- chronic diarrhea and malabsorption/weight loss may follow acute infection even with treatment
- fever / GI bleeds unusual = noninvasive
sulfur burps!!
What is mech of giardia lamblia infection/life?
- ingest cyst
- gastric acid –> excystment of cyst into trophocoites in proximal small intestine
- absorbs nutrients from host, inhibiis host digestive enzymes
- possible diffuse loss of brush border
- zoonotic reservoirs
Is giardia invasive?
No!
How do you diagnose giardia?
- direct florescent antibody to giardia antigen
- cysts in stool
What is incubation period of giardia?
5-20 days
Where is geo of giardia?
world wide, north america
What is treatment for giardia?
- tinidazole or metronidazole [Flagyl]
What does trichomonas vaginalis commonly cause?
- vaginitis, cervicitis, vaginal discharge, pruritis/irrritation
- usually asymptomatic in males or may have urethritis
Does trichomonas vaginalis have cyst form?
nope
how is trichomonas vaginalis transmitted?
- sexually transmitted, women more symptomatic
what should you avoid on tinidazole?
avoid alcohol completely –> can feel flushed/fever/ab pain/life threatening
What other diseases co-occur with trichomonas vaginalis?
- associated with other STDs [especially gonorrhoea]
- bacterial vaginosis
How do you diagnose trichomonas?
- wet prep exam –> detect very motile organisms
What are complications of trichomonas in pregnant woman?
- low birth weight, pre term delivery, premature rupture of membranes
What is relation trichomonas and HIV?
- if you have trichomonas, you are at higher risk for contracting HIV / have higher viral load
Where do you see trichomonas?
- worldwide –> higher in people with multiple sex partners or other venereal disease
How do you treat trichomonas?
- systemic or intravaginal sopositories of metronidazole or tinidazole
- partner treatment
Why is tinidazole sometimes better than metronidazole?
it has fewer side effects
What are associations to differentiate trichomonas vaginalis, trichuris trichiura, trichinella spiralis?
trichomonas vaginalis: vaginitis
trichuris trichiura: whipworm, rectal prolaspe
trichinella spiralis: consumption of wild boar
How do you get trichinella spiralis?
- ingest larvae encysted in undercooked meat [pork]
What is pathogenesis of trichinella infection?
- larvae ingested
- larvae mature in intestine, females deposit new larvae
- larvae penetrate bowel and enter circulation
- larvae penetrate skeletal muscle, cause inflammatory response
What are clinical features of trichinosis spiralis?
- fever, myalgias, orbital edema, elevated CPK, eosinophilia
How do you confirm trichinosis spiralis diagnosis?
- by muscle biopsy = spiral shaped appearance or serology
What is treatment for trichinosis spiralis?
- mebendazole and steroids
Where do you see t spiralis infection?
temperate climates, northa america, europe, south america, asia
What animals get infected with T spiralis?
- polar bears, walruses, wild bears, boars
What is distribution of intestinal spore-forming protozoa?
- worldwide
How do you diagnose intestinal spore forming protozoa?
- visualize parasite with acid fast of stool
- immunostatin [DFA to cryptosporidium]
What are the four intestinal spore-forming protozoa?
- cryptosporidium, isospora, cyclospora, microsporidium
How do you treat the 4 intestinal spore forming protozoa?
- immune reconstitituion [for microsporidia. cryptosporidia]
- nitazoxanide
- trimethoprim/sulfa [isospora, cyclospora]
What are clinical signs of intestinal spore forming protozoa?
- severe watery diarrhea usually in immunocompromised
What is mech of transmission intestinal spore forming protozoa?
ingestion of cyst form
What is life cycle of cryptosporidium parvum?
- entire cycle wthin enterocytes
- ingestion of oocyte spores begins life
- has asexual and sexual cycles
- leads to autoinfection cycle
How is cryptosporidium parvum transmitted?
- ingestion of oocytes from contaminated food/water/recreational water [water park, rafting]
- can get it from feces of animal reservoirs [cattle/sheep]
What are clinical signs of cryptosporidium parvum
- voluminous diarrhea, bloating, malabsorption
What does cryptosporidium cause in HIV? in immunocompetent?
HIV: wasting syndrome
competent: diarrhea/bloating
Cryptococcus vs cryptosporidium?
Cryptococcus: opportunistic pneumonia/meningitis
cryptosporidium: opportunistic GI
What is life cycle of isospora? appearance?
sexual and asexual stages
eye appearance on biopsy
Where is isospora belli endemic?
Africa, asia, south america
how do you detect isosospora?
acid fast stain
What is cyclospora associated with?
- multistate food outbreaks: lettuce, rasberrries
Where is cyclospora cayetanensis found?
- worldwide distribution
What clinical findings of cyclospora cayetanensis?
- protracted relaspsing gastroenteritis
- in immunocompromised: profound watery diarrhea –> death
What is pathogenesis of cyclospora cayetanensis?
- oocysts secreted unsporulated
- after days - wks outside host, sporulate and become infectious
- mature oocyte ingested
What are features of microsporidium cell?
- nucleated
- single celled obligate intracellular protozan parasite
- lacks mitochondria
- has polar tube
Who does microsporidium infect? geo distribution?
- broad range vertebrates, invertebrates
- very rarely see in immmunocompetent
- get it from water, animals, food producing farm animals
What are clinical signs of micropsoridium?
- in immunocompetent travelers: self limiting or chronic diarrhea [very rare]
- in compromised: chronic diarrhea [more intense], can disseminate –> encephalitis, sinuses, nephritis, hepatitis
- AIDS related eye infections
