Entamoeba Histolytica Flashcards
Entamoeba histolytica
Affected people?
Affected people are mostly asymptomatic + act as carriers spreading organism
-Entamoeba histolytica
MoT
Consumption of water or food contaminated with cysts from stools of an infected person
Sewage with cysts may contaminate water systems,
((.Oral-anal sexual intercourse may also lead to transmission))
Organs affected
Deep mucosal ulcerations with intestinal haemorrhage
• INVASIVE some cases – submucosal tissue – enterohepatic circulation – other organ involved
• PRIMARILY LIVER, but also lungs, brain or heart - ABCESSES
Entamoeba histolytica – clinical manifestations
3 possible outcomes
1. Asymptomatic carriage 2. Intestinal disease
3. Invasive disease
Asymptomatic carriage
• Majority, almost 90% - cysts spread in the environment
Intestinal disease
• Abdominal cramps, colitis with haemorrhagic diarrhea
Invasive disease
• Systemic (fever, rigors, leucocytosis), plus extraintestinal amebiasis – LIVER ABCESS most
common, followed by lungs & CNS
Diagnosis
• Differentiate between pathogenic amoeba (E. histolytica) and NON-PATHOGENIC amoeba (E.
dispar, E. moshkovskii) – E. histolytica contains ingested RBC
‘Entamoeba histolytica – diagnosis
Stools
• Microscopy, search for trophozoites or cysts in the case of colitis
• Stool antigen detection, again, more sensitive for colitis, less for invasive disease
• Serum antigen detection, more sensitive for invasive disease
• PCR in stool or liver abscess aspirate, used for both colitis & invasive disease
• Serology, used for both
Free living amoeba
Acanthamoeba spp
MoT
Epidemiology
Found in water & soil – enter body through skin or respiratory tract
Immunocompetent, AMOEBIC KERATITIS from lenses contaminated with water
Naegleria fowleri = “BRAIN EATING AMOEBA”
• Thermophilic – spas, rivers, lakes, non-chlorinated swimming pools – NOT in salt water
• Nasal inoculation of contaminated water – PRIMARY amoebic meningoencephalitis
• After recreational water exposure, almost 100% fatal
Flagellates
Giardia
• G. lamblia, motile, similar stages to E. histolytica (trophozoites, cysts)
• Worldwide, !in rivers, lakes!, mountains – maintained in nature mostly by beavers & muskrats
• !Ingestion of cysts through contaminated water (mountain streams, lakes, etc.), uncooked
vegetable or fruits!, person-to-person through fecal-oral route, or oral-anal route
• Outbreaks may occur in closed crowded settings or intrafamilial • Gastric acid stimulates excystation, trophozoites released in duodenum & jejunum & multiply by
binary fission & attach to intestinal villi through a sucking disk
• Do NOT destroy tissue, DO NOT INVADE
‘Giardia lamblia clinical manifestation
!DIARRHEA, foul smelling, watery diarrhea!, abdominal cramps, flatulence & steatorrhea
• No blood or pus in stools – NOT invasive
• Chronic diarrhea & in severe cases it may cause malabsorption, esp. in children
Giardia lamblia
Diagnosis -
Stools
• Microscopy, cysts or trophozoites • If stools negative, but clinical suspicion high, duodenal aspirate • Stool antigen detection • Stool PCR
-Trichomonas vaginalis
Flagellated protozoon with 4 flagella,! urogenital infections, no cyst stage!, only trophozoites, in urethras & vaginas of women & urethra & prostate glans of men
• Worldwide – sexually transmitted disease. Transmission from toilets has been reported, although rare
• Prevalence amongst women is around 10% & amongst men 5%
Men
• !Usually asymptomatic carriers! transmit to women, occasionally, balanitis, prostatitis, urethritis
Women
• Asymptomatic or mild symptoms, mild, watery vaginal discharge
• In some cases vaginitis may occur with itching, burning & painful urination
-Trichomonas vaginalis
Diagnosis
Diagnosis
• Microspocy of stained (Giemsa, Papanicolaou) or unstained vaginal or urethral discharge • PCR, culture or fluorescent antibodies
Next slides not as important
