CYCLOSPORIASIS

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CYCLOSPORIASIS

• Cyclospora cayetanensis
• unicellular parasite known as coccidia (1994)
• previously known as cyanobacterium-like or
  coccidia-like body (CLB)
• oocysts not infective--sporulation occurs after
  excretion, which differentiates Cyclospora from
  Cryptosporidium
• first human case reported in 1979
• reported in US since 1994

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CYCLOSPORIASIS

• Microbiology
• oocysts are spherical, 9? in diameter
• low to moderate numbers are passed in feces
• readily detected with conventional microscopy

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CYCLOSPORIASIS
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CYCLOSPORIASIS

• Life cycle
• typical of all enteric coccidial infections
• ingestion of a sporulated oocytes (each
  containing 2 sporocytes with 2 sporozoites
  enclosed within)
• sporozoites penetrate epithelial cells of small
  intestine (especially jejunum)
• merogony
• undergo multiple fission to form meronts, which
  contain multiple merozoites (2 generations)
• later generation merozoites penetrate new cells
  and form gametes

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CYCLOSPORIASIS

• Life cycle
• typical of all enteric coccidial infections
• gamogony
• most gametes enlarge, forming the female
  macrogamete
• a few become sperm-like microgametes which
  fertilize the macrogametes
• oocyst wall is layed down around the zygote
• unsporulated oocyst sloughs from intestinal wall
  and is passed in the feces
• sporogony (sporulation)
• development of sporocysts and sporozoites
• occurs only in the presence of higher atmospheric
  oxygen concentrations, particularly in warm, wet
  soil
• complete within 7-12 days

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CYCLOSPORIASIS
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CYCLOSPORIASIS

• Epidemiology
• ubiquitous, worldwide distribution
• overall prevalence lt 1
• outbreaks more likely in warmer months
• increased sporulation
• increased importation of produce (in US)
• reservoir
• primarily humans although has been isolated from
  non-human primates (chimpanzees and baboons)
• dogs, poultry (parasitic or incidental?)

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CYCLOSPORIASIS

• Pathogenesis
• inflammation of small intestine
• changes in mucosa
• villous atrophy
• crypt hyperplasia

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CYCLOSPORIASIS

• Clinical signs
• symptoms usually appear 1 week after ingestion of
  oocysts
• prolonged watery diarrhea, cramping, weight loss,
  anorexia, myalgia
• occasionally vomiting and fever
• may persist for up to a month
• mild infections with few or no clinical signs may
  occur

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CYCLOSPORIASIS

• US Outbreaks
• before 1966, most cases were sporadic -
  associated with travelers diarrhea
• 1996 (US) - imported raspberries from Guatemala
• 1465 cases reported by 20 states, DC, and 2
  provinces (Canada)
• 725 associated with cluster outbreaks
• 740 sporadic cases
• all east of Mississippi except for Colorado
• 22 hospitalizations, no deaths
• 978 cases confirmed

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CYCLOSPORIASIS

• Guatemalan raspberry outbreak
• source
• only exposure consistently associated was
  consumption of raspberries
• 34 of 36 farms sold to a particular exporter
• although filtered water used for irrigation, not
  microbe-filtered
• agricultural water is also used to mix
  insecticides and fungicides sprayed directly on
  berries as late as the day they are picked

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CYCLOSPORIASIS

• Guatemalan raspberry outbreak
• source
• dont know if contaminating oocysts were animal
  or human source, or if they were unsporulated (on
  workers hands) or had already sporulated
• studies in Guatemala to establish prevalence is
  underway
• to date, no animal reservoirs have been identified