Cryptosporidiosis of mammals and birds

Question 1

Cryptosporidium species:

Answer 1

C. hominis - human
C. parvum - human, canines
C. canis - canines
C. felis - feline
C. muris - rodents, feline
C. meleagridis - turkey & other birds
C. baileyi - chicken & other birds

Question 2

location of cryptosporidium species

Answer 2

• Microvilli of digestive tract
• Respiratory tract
• intracellular extracytoplasmic

Question 3

Morphology of cryptosporidium species

Answer 3

• 0 sporocysts, 4 sporozoites
• Smaller oocysts has higher affinity for intestinal enterocytes - C. parvum
• Larger oocysts has higher affinity for stomach glands - C. muris

Question 4

transmission of cryptosporidium species

Answer 4

Oral ingestion

Question 5

life cycle of cryptosporidium species

Answer 5

1) Endogenous Sporogony - Sporulated oocyst is releases in the environment (sporulates inside host). Oocyst is ingested by final host.
2) Endogenous Merogony - oocyst excyst in the intestines and releases Sporozoites. Each sporozoite invade epithelial cells - MEROGONY - inside cells do binary fission to form schizont/meront containing merozoites. The cell ruptures and releases the merozoites which infects new cells.
3) Endogenous Gametogony - inside intestinal cells, the merozoites becomes microgamete (male) and macrogamete (female) - fuses nuclei producing a ZYGOTE –> OOCYST, which then sporulates inside the host (Sporogony) - this produces either thick-shelled oocyst or thin-shelled.

PP: 1-12 days

Question 6

pathogenesis of cryptosporidium species

Answer 6

Villous atrophy, necrotic enteritis, enterocyte metaplasia, crypt hyperplasia, digestive function is impaired. Young are in warning.

Sporozoites invade enterocytes in distal small intestine, sometimes colon. This leads to shortened and blunted villi, and reduces absorptive area leading to malnutrition. Crypt cells proliferate to compensate for reduced villi, leading to immature, poorly functioning epithelial cells lining the gut. Surviving epithelial cells undergo structural and functional changes, resulting in loss of digestive enzymes and absorption capacity. The damaged mucosa can become necrotic, which may lead to secondary bacterial infections and more severe enteritis.
Young animals are at risk due to immature immune system, high environmental exposure and close animal contact.

Question 7

clinical signs of cryptosporidium species

Answer 7

Watery profuse diarrhoea, dehydration, anorexia, electrolyte imbalance

Question 8

diagnosis of cryptosporidium species

Answer 8

Direct faecal smear - too small for flotation

Question 9

treatment of cryptosporidium species

Answer 9

Halofuginone - calves
Paromomycin - lambs, goats
Azithromycin - foals, dogs
Nitazoxanide - foals, calves

Birds:

• Toltrazuril - pigeons and poultry
• Sulfanomides - mixed infections
• Diclazuril

Highly resistant to disinfectants - use ammonia or hydrogen-peroxide disinfectants, or steam cleaning
* No drug for humans - supportive care

Question 10

What is the difference between the thin-shelled and the thick-shelled oocysts of Cryptosporidium?

Answer 10

Thick-shelled (80%) can go to external environment and is already sporulated.
Thin-shelled (20%) stays inside the host to do autoinfection (re-infection)