Lecture 13: Amoeba and Ciliates Flashcards
What type of parasite is an amoeba
Protozoa
T or F: amoeba’s require a host
False, don’t require a host but benefit from interaction
What are facultative parasites
Parasites that don’t require a host to live but benefit from the interaction
Ex: amoeba
What are the most important amoeba in vet medicine
- Entamoeba histolytica
- Entamoeba invaders
- Acanthoamoeba spp.
- Naegleria fowleri
What species does Entamoeba histolytica typically infect
Dogs, cats and humans
What species does entamoeba invadens typically infect
Reptiles
What species does ancanthamoeba spp. typically infect
Usually humans, but a variety of species in vet med
What species does naegleria fowleri typically infect
Primates, cattle
What are the life stages of amoeba
- Cysts
- Trophozoites
Which amoebic life stage can be described as amoeboid, motile and feeding/pathogenic
Trophozoite
What amoebic life stage can be described as round, non-motile and environmentally resistant
Cysts
Which stage of amoebic life stages can be infectious and which can actively invade tissues
- Both cysts and trophozoites can be infectious BUT
- Only trophozoites can actively invade tissues
What are the common routes of infection for amoeba
- Ingestion: fecal-oral
- Nasal mucosa (inhaled)
- Eyes
- Skin abrasions
T or F: amoeba infections are often asymptomatic
True but infection possible
Who is most susceptible to amoeba infection
Young and immunocompromised
What body organs can amoeba go
Intestines, extra intestinal, liver, lungs, and brain
How do amoeba migrate to the Brain
Olfactory portal is highway to the brain. The cribiform plate has holes in it for the olfactory nerves to pass through and amoeba can crawl up the nerves, through the holes in cribiform plate and into the brain
What are the most common mechanisms of pathogenesis for amoebic infections
- Malabsorption (damage to colon)
- Direct tissue destruction (liver and brain)
- Inflammatory response
What are the morphological features of E. Histolytica cysts
Round to oval, 4 nuclei, blunt chromotoidal bar
What are the morphological features of E. Histolytica trophozoites
1 nucleus, central karyosome
what is this, infects dogs and cats
E. Histolytica cyst
What is this, infects dogs and cats
E. Histolytica trophozoites
What reptiles are highly susceptible for E. Invadens
Boas, colubrids, vipers, crotalids
What reptiles are resistant to E. Invadens and serve as reservoir hosts
Chelonians (turtles), crocodilians, cobras, eastern king snakes
What is the most common route of infection for E. Invadens
Fecal-oral
How can you tell E. Invadens apart from E. Histolytica
Morphologically Indistinct but E. Invadens is not transmissible to mammals
What does E. Invadens cause when it invades the intestines
Transmural necrohemmorrhagic enterocolitis
What are the clinical signs of an intestinal infection with E. Invadens
Anorexia, vomiting, mucous or hemorrhagic diarrhea, sudden death
What loss of the intestinal barrier due to E. Invadens can lead to ___
Sepsis
The following images were take from colon of a reptile. What is wrong
Infection with E. Invadens most likely causing transmural necrohemorrhagic colitis
How does extra intestinal infection of E. Invadens happen
The shared flow between the liver and small intestines via the portal vein and common bile duct cause the infection to bread outside the small intestines
What does E. Invadens extra intestinal cause
Entercolitis—> subsequent hepatitis following hematogenous dissemination via the portal vein
what do Acanthomoeba spp. trophozoites look like
Nucleus with a karyosome, filamentous pseudopods
what do Acanthomoeba spp. cyst look like
Nucleus with a karyosome, inner and outer cysts
What is the this amoeba
Acanthomoeba spp. trophozoite
What is this amoeba
Acanthomoeba cyst
What Trophozoite and cysts amoeba do these belong to
ancathnomoeba spp.
T or F: infection via Naeglera fowleri can occur by swallowing contaminated water
False
What is typically the only way a naegleria fowleri infection can be spread
Inhalation
The following amoeba is known to infect cattle and primates, what is it and what life stage
N. Fowleri cyst
The following amoeba is known to infect cattle and primates, what is it and what is the life stage
N. Fowleri Trophozoite
The following amoeba is known to infect cattle and primates, what is it and what is the life stage
N. Fowleri free living flagellate
What is the primary disease caused by N. Fowleri
Primary amoebic meningoencephalitis
The following was taken from a cows brain for a suspected amoeba infection. What is the most likely amoeba to be indicated and what has it caused
N. Fowleri causing primary amoebic meningoencephalitis
What is the main therapy option for amoebic infections: drug, dose, duration, and mechanism of action
Drug: metronidazole
Dose: 10-25mg/kg
Duration: PO BID for 1wk
MOA: inhibits DNA synthesis
T or F: metronidazole can be given to food animals
False, on FARAD list of drugs never allowed
What two life stages do ciliates have
Trophozoites and cysts
Ciliates have __ all around the trophozoites and cysts
Cilia
What type of nuclei do ciliates have
Dimorphic nuclei- macro nucleus with 1-several micro nuclei
T or F: ciliates are considered to be non-pathogenic/commensal
True, but can cause disease in rare cases
Describe the pathogenesis of Balantidium coli in the rare case that it causes disease vs normal
Normally, B. Coli doesn’t enter colon and cause tissue destruction, normally is just passed in feces
Infectious: trophozoites enter colon and cause tissue destruction
The following was taken from the colon of a pig showing signs of a parasitic infection. What is the most common ciliate to be implicated. Also is this a Trophozoite or cyst- how can you tell
Trophozoite- lots of cilia, and this is Balatidium coli
The following was taken from a pigs feces with a suspected parasitic infection. What is the most common ciliate to be implicated and it this a cyst or Trophozoite and how do you know
cyst- less obvious cilia and this is B. Coli
The following Protozoa are found in forestomach of cows and hind gut of horses. Is this parasitic or commensal
commensal