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MMI 426 > Balantidium & Cryptosporidium > Flashcards

Balantidium & Cryptosporidium Flashcards

1
Q

first recognized in two humans with dysentery in 1857

A

Balantidium coli

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2
Q

only ciliated protozoan known to infect humans

A

B. coli

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3
Q

largets protozoan infecting humans and non-human primates

A

Balantidium

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4
Q

vehicle of Balantidium for most cases

A

water

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5
Q

T or F. Balantidiosis is a zoonotic disease

A

T

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6
Q

definite host of Balantidium

A

porcein
- asymptomatic in pigs and humans
- can be found wherever pigs are found
- human to human may occur but RARE

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7
Q

biology and life cycle of B. coli

A
  • unicellular trophs covered in cilia (longitudinal wavelike motion); 30 to 150 um by 25-120um
    > vestibule is anterior portion of mouth
    > cytostome is the mouth
    > cytophage = anus where waste is discharged
    > macronucleus = shaped like large sausage; non-reproductive functions like feeding and metabolism
    > micronucleus = small organ that sits below macronucleus; genetics and cell division
  • cyst
    > transmissive stage (40 to 60 um in diameter)
    > tough membrane (formed as trophs move down intestines
    > can survive dessication & environmental stage
    > survives best in human surroundings protected from sunlight
    > bacteria and food particles and RBCs main food source
    > no nuclear/cytoplasmic division
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8
Q

T or GF. Micronucleus of B. coli is easily seen on the microscope

A

F

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9
Q

where can B. coli cysts be seen?

A

in formed stool; macronucleus = thick double wall; transmittive stage

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10
Q

how does B. coli reproduce?

A

asexual = transverse fission; occurs for most ciliates

sexual = conjugation followed by binary fission
> role of macro- and micronucleus here
> during binary fission= exchange of micronuclear material; macro will disintegrate during conjugation; new one formed by micronucleus => binary fission will then occur
- two sizes of trophs (large and small) are formed during conjugation; never bw same sizes

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11
Q

simple life cycle of B. coli

A
  • ingestion of contaminated food or water
  • hatching of parasite
  • gut invasion of parasite
  • encystation of trophs
  • excretion of cysts
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12
Q

B. coli = lesions formed due to ulcers in colon

A

forms flask shaped lesions in submucosa
= form clusters which are referred to as nides or nes

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13
Q

lumen dwellers

A

B. coli
- cecum and colon

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14
Q

gut wall invasion of B. coli produces this enzyme

A

hyaluronidase
- degrades intestinal tissue & digests hyaluronic acid = glue that holds mucosal epi cells together
- during invasion = bacterial and inflammatory rxn occur
- mucosa ulcers and subsurface abscesses form
- mucosa and submucosa are damaged
- muscular layer also affected =hemorrhage and necrosis

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15
Q

extraintestinal invasion of B. coli

A
  • may include appendix
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16
Q

T or F. B. coli produces many toxins that help with pathogenesis

A

F! does not produce any known toxins

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17
Q

symptomatology of B. coli

A
  • asymptomatic in humans and pigs
  • diarrhea -> dysentery (nausea, vomiting, or headache)
  • rarely appendicitis , UTI, vaginitis/cervicitis, peritonitis
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18
Q

B. coli reservoir

A

zoonotic disease
normal host (75% pigs)
also monkey, dog, cattle, sheep, rat
- high prevalence in poor rural areas such as Latin America, Philippines, etc.

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19
Q

how are humans affected by . coli

A
  • fecal oral-route
  • sewage sludge (human waste as fertilizer)

risk factors: pig farmers, slaughterhouse workers, vets, poor nutritional status, intestinal flora not normal, and also dependent on parasitic load, alcoholics, etc.

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20
Q

epidemics of B. coli

A

mental hospitals and prisons

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21
Q

B. coli diagnosis

A

stool microscopy (trophs more prominent than cysts (maybe difficult to ID; can be confused by other helminths))

tissue biopsy of colon

cultivation (grow between 20C to 40C)

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22
Q

prevention of B. coli

A

improved sanitation and hygiene for water and food supply

chlorine not effective against thick wall of B. coli cysts

prevent contamination of water source by pigs/human feces

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23
Q

treatment for B. coli

A

tetracycline
or metronidazole flagyl

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24
Q

minute coccidian parasite

A

Cryptosporidum
12 separate species
> 2 important for humans: C. hominis and C. parvum
> worldwide in distribution
> molecular characterization distinguishes human and domestic animal species

25
Q

humans and monkeys Crypto

A

C. hominis

26
Q

humans and cattle Crypto

A

C. parvum

27
Q

two forms of Cryptosporidium

A

cyst stage
- infective stage = oocyst = 4 sporozoites
> thick and thin walled variety
> thick = survive in stool
> thin = burst in gut and infect internally

troph stage
- transitional stage (uninuclear) = sporozoites and merozoites to multinucleate meront

28
Q

two types of meronts

A

type I = first asexual generation

type II = develop from Type I produce micro- and macrogamonts (male and female –> goes o to produce zygote (pregnant cell))
> develop thick and thin walled oocyst => thin wall = other infection; thick => exit in feces)

29
Q

where do Crypto cysts rest in the intestine?

A

villi

30
Q

modified Kinyon stain

A

used for Crypto cysts

31
Q

complicated life cycle of rypto

A

transmission = inhalation or containated water

oocysts = 4 sporos = infective stage

after ingestion = excystation = release of sporos

leads to formation of trophs

then first asexual cycle = meront type I = contains 6-8 meros

type II = 4 merozoites => sexual cycle

formation of gamonts = fertilization of macrogamont by the microgamonts (males)
= zygote

sporulating oocysts produced after zygote
> thin walled = autoinfection
> thick walled = exit host in feces

32
Q

Cryptosporidium hosts

A

no one is safe!
can be seen as zoonotic and “gum to bum” disease

fish and snakes birds
mice,
rats rabbits,
guinea pigs cats,
dogs squirrels calves horses pigs sheep goats monkeys humans

33
Q

pathology and pathogenesis of Crypto

A
  • located in GI tract of epithelium and crypts of small intestine

histological changes:
- blunting/loss of villi
- lengthening of crypts
=> cellular infiltration (plasma cells, neuts, macs and lymphs => development of diarrhea and cause infection

34
Q

less common sites of infection of Crypto

A

stomach
appendix
colon
rectum
gall bladder
pancreatic duct
?? pulmonary tree = certainty of disease/contam is not always clear

> diarrhea with large fluid loss
dehydration
malabsorption in some patients

35
Q

T or F. Crypto can be seen in sputum

A

T!

36
Q

two syndromes of Crypto

A
  1. immunocompetent host
    > children are the majority
    > incubation period = 1d to 1wk (or 30 d)
    > watery diarrhea
    > abdominal pain/bloating/gas/vomiting
    > low grade fever
    > duration is 1-2 wks or 1-2 months

spontaneous resolution
shedding of oocysts 8-50 days

  1. immunocompromised
    *same as above** but more severe
    massive (8-20L/day) fluid loss
    malabsorption
    > duration is many months to years
    ; reversible as immunosuppression
  2. pulmonary infection
  3. other areas of G = cholangitis, pancreatitis, hepatitis
37
Q

public health concern for Crypto

A

daycares and food handlers

38
Q

geographical distribution of Crypto

A
  • 5 continents
  • urban and rural
  • developing > develop countries
    newer molecular surveys = higher prevalence
  • Crypto seen more in non-breastfed infants
  • exposure vs asymptomatic excretion and immunity
  • seroprevalence studies = 15-90%
39
Q

age distribution of Crypto

A

3 days to 95 yrs
highest prevalence = <2yrs
daycare outbreaks

40
Q

sex distribution of Crypto

A

males less likely to get sick
(based on relation to children; women care for kids more in general)

41
Q

special groups high risk to Crypto

A

AIDS = high distribution
no seasonality or may see higher % during spring esp. in climate like Canada that goes from winter to spring where you have runoff from melting of snow which can lead to contamination of water system

42
Q

transmission of Crypto

A
  • ingestion of oocysts (10 to 3000)
    > zoonotic
    > person to person (includes b/w sexual partners)
    > contaminated water (including swimming pools), food
43
Q

number 1 source of transmitting Crypto

A

water = esp swimming pools

44
Q

prevention of Crypto

A

ubiquitous so oocyst inactivation

> exposure to temp below )c and above 65C for 30 mins
filtering driving water
10% formol saline and 5% ammonia OR commerical bleach

no treatment can guarantee removal of oocyst

45
Q

diagnosis of Crypto

A

intestinal biopsy material = EM; could reveal meronts containing merozoites (asexual) OR gamonts containing micro and macrogametes (sexual stage)

46
Q

specimen for Crypto

A

preserved stool = oocysts can be detected using special stains like mod acid-fast

47
Q

duodenal string test

A

enterotest for Crypto
> recovers oocysts

48
Q

how to recover oocysts after enterotest

A

flotation and sedimentation
- H&E to stain organisms lightly = appear as small round bodies on the mucosal surface
- safranin-methylene blue
- Giemsa
- Auramine
- Acridine orange (fluorescence)

49
Q

what does mod. acid-fast stain crypto?

A

oocysts appear red

50
Q

these are being used more routinely to diagnosis Crypto, but mainly for research purposes

A

PCR

51
Q

flotation

A

parasites found at top of tube

52
Q

sedimentation

A

formalin ethyl acetate sedimentation method = parasites found at bottom = bc sedimented and 3 other layers on top = ethyl acetate, debris, then formalin

all three top layers removed

only bottom layer where parasites should be is kept

53
Q

T or F. Stool processing method used here is Flotation

A

F! We use formalin ethyl acetate sedimentation method

54
Q

disadvantages of sedimentation

A
  • some parasites can’t withstand centrifugation
    > developmental and reproductive stages of protozoa
  • some parasites require longer/faster centrifugation
    ex: Cryptosporidia
55
Q

purpose of sedimentation

A

to separate parasites from bulk of feces (undigested food)
- concentrate parasites so less specimen needed for analysis

56
Q

stain used for Crypto

A

modified Kinyon stain

57
Q

T or F. Treatment is available for immunocompetent patients with Crypto

A

T! AIDS patients have no effective treatment for Crypto and must treat underlying HIV infection

58
Q
A

MMI 426 (20 decks)

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