Cryptosporidium spp

Question 1

How is Cryptosporidium spp. classified?

Answer 1

Intracellular protozoa belonging to the category sporozoan or apicomplexa

Question 2

Who gets infected with cryptosporidium spp. and what cells does it target?

Answer 2

Humans (non-zoonotic)

• C. hominis
• C. Parvum

Animals (zoonotic)

Target: epithelial cells GI tract but does not enter the cell - Upon the initial interaction between the parasite and intestinal epithelial cell there is junction formation (the microvilli of the intestinal epithelial cells lengthen, flatten and fuse to surround the parasite)

Question 3

How is Cryptosporidium spp transmitted?

Answer 3

fecal-oral route
water-borne - contamination of water by sewage and/or agricultural waste
food-borne (e.g. raw milk)

Question 4

What is the infective stage of Cryptosporidium spp.?

Answer 4

Oocysts

Question 5

What is the life cycle of Cryptosporidium spp.?

Answer 5

1. Sporulated oocysts containing 4 sporozoites are excreted by an infected host through the feces. The oocyst is protected by a thick, hardened cell and can remain infectious for 6-8 months in optimal circumstances outside the body. They are resistant to heat, cold, and chlorine-based disinfectants like pool water
2. Transmission of cryptosporidium through injection of by feces contaminated food or water or direct contact with the infected animal or human ‘
3. Ingestion by a suitable host. Most genome types are host-specific but humans are not specified by a certain genome. C. parvum can infect humans, kettle, sheep, goats, horses, pigs and mice
4. Excystation of oocysts happens and sporozoites escape from the cyst and are released into the epithelial cells of the GI tract are attacked (possibly also the respiratory tract)
5. Asexual multiplication takes place by merogony or sysogomy
6. Sexual multiplication takes place (gematogony) and microgametes (male) and macrogamonts (female) are produced. Both types grown and the microgametes are released and land on macrogamonts and fertilize them and a zygote is produced
7. Zygote gives rise to 2 different types of oocysts a thick and a thin wall oocyst. The thick-walled are excreted into the environment and the thin-walled stay and are involved in the internal auto infective cycle (so not recovered from stools)
8. The thick wall is excreted by the host and the cycle starts anew

Question 6

What type of life cycle does Cryptosporidium spp have? And what kind of host are humans?

Answer 6

Direct life cycle

Humans - definitive host

Question 7

What are other hosts of Crytosporidium spp. besides humans?

Answer 7

wide range of vertebrate hosts, including birds, reptiles, and mammals - Cattle are major hosts for C. parvum (zoonotic subtype families)

Question 8

What is the incubation time of Cryptosporidium spp.?

Answer 8

7 days (range 2-10 days)

Question 9

What are the symptoms of Cryptosporidium spp.?

Answer 9

`Ranging from asymptomatic to symptomatic (mild acute - chronic)

• common symptoms: watery diarrhea, stomach cramps or pain, dehydration
• endogenous intestinal stage: microvillus destruction, villus atrophy, impaired
  glucose, and electrolyte transport, impaired carbohydrate and protein digestion
  manifesting in malabsorptive and maldigested disease
• fetal for immunocompromised individuals

Question 10

Where is cryptosporidium spp. endemic?

Answer 10

Worldwide - most likely developing countries (linked to swimming pools, water playgrounds, and other swimming venues; unpasteurized cider, juice, and milk; contact with animals; childcare settings; camps; and ill food handlers)

Question 11

How is cryptosporidium spp diagnosed?

Answer 11

• detection of oocysts
• PCR on feces sample
• Other tests are examination of stool samples using a modified acid-fact stain using
  microscopy or enzyme immunoassays for detection of antigens

Serological tests are only relevant for epidemiological research as the presence of specific antibodies are not correlated to a on that moment present infection.