Focus on pathogens: Balantidium coli

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Focus on pathogens Balantidium coli

• Epidemiology Balantidiasis is found worldwide
  and is most prevalent in poor agricultural areas,
  especially those where swine are raised (some
  data suggests a unique link between balantidiasis
  in swine and humans?). Endemic areas are
  exclusively tropical. Prevalence runs from 1-5
  in endemic areas. Prevalence in children in
  certain localized hot spots approaches 100.
  Bolivia seems to be the most endemic area for B.
  coli infection.

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Focus on pathogens Balantidium coli

• Pathology / clinical symptoms most human
  infections are asymptomatic. When pathological,
  resulting symptoms are limited to gastroenteritis
  (diarhea, cramps, etc/) in the vast majority of
  cases, with a notable resemblance to amoebiasis.
  Some patients develop the flask-like mucosal
  ulcerations also seen in amoebiasis. The
  greatest distinction (vs amoebiasis) is that the
  organism is rarely invasive, affecting only the
  mucosa and sub-mucosa causing limited dysentary
  B. coli is usually happy in the colon eating
  starch and bacteria. Very rarely the organism
  will pass to extra-intestinal tissues as does E.
  histolytica. Clearly, the condition can be
  easily misdiagnosed if going by symptoms alone.

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Focus on pathogens Balantidium coli

• Laboratory diagnosis of trophozoites
• large size 50-100uM long, 40-70uM wide
• oval with one rounded and one more pointed end
• troph covered with cilia these can be hard to
  see
• characteristic wave-like rotary motility via
  cilia
• oral groove or cytostome on the pointed end
• bean-shaped (sausage?) macronucleus iodine
  wet mt

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Focus on pathogens Balantidium coli

• Laboratory diagnosis of trophozoites
• large size 50-75uM
• round - ovoid
• macronucleus present here as in troph
• may see cilia inside cyst, especially in young
  cyst
• Summary easily identified by wet mount or
  stained smear

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Pathogenic intestinal Sporozoa Coccidia
sub-group (order?)

• Cryptosporidium parvum
• Cyclospora cayetanensis
• Isospora belli
• Review characteristics of Sporozoa on slides
  25-30. Weird dudes they are.

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Focus on pathogens Cryptosporidium parvum

• Facts / life-cycle C. parvum is a tiny protozoan
  which lives on (vs Sporozoa description) host
  epithelial cells, usually intestinal microvilli.
  Cryptosporidiosis is considered a zoonosis (cows,
  hogs, dogs, cats, chickens and other animals have
  been implicated) because oocysts pass in feces
  via agricultural run-off to contaminate water.
  Recently added focus has been on Canada geese and
  shellfish oysters. Humans are considered
  accidental hosts. C. parvum cysts are the 1
  most chlorine resistant parasite cyst type (more
  than Giardia). They can pass unharmed in treated
  water causing sporadic infections in large
  numbers of urban dwellers. Infections also arise
  from recreational waters or contaminated well
  water often following large rains. Severity of
  the condition ranges dramatically depending upon
  immune health.
• ? chlorine resistant ?immune resistant READ
  1093-94 ?

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C. parvum facts / life-cycle cont.

• From oocysts arise 4 sporozoites (trophs) which
  parasitize epithelial cells (usually GI tract).
  These undergo mitosis to form merozoites which
  can themselves be infective (auto-infection type
  1), or they can undergo meiosis to form gametes.
  Gametes fuse to form the zygote which eventual
  encysts to form 2 possible types of cysts 1. a
  thick-walled cyst is commonly excreted in feces
  to complete the life-cycle and 2. a thin-walled
  cyst liberating sporozoites which can be continue
  the infection (auto-infection type 2).
• Oocysts are infective upon excretion, thus
  permitting direct and immediate fecal-oral
  transmission.  Human to human transmission is
  possible but rarely occurs.

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