Cryptosporidium spp

Question 1

What kind of parasite is Cryptosporidium?

Answer 1

Apicomplexan protozoan

Question 2

Cryptosporidium is the most common parasitic cause of … in humans worldwide

Answer 2

Diarrhoea

Question 3

Describe the features of the life cycle of Cryptosporidium

Answer 3

• Direct
• Parasitizes mucosa
• Intracellular

Question 4

Where is cryptosporidium found in the host?

Answer 4

• Found in the microvillus border of epithelial cells lining alimentary and respiratory tracts
• Sits on top of the cell, outside the cytoplasm, covered by outer cell membrane

Question 5

What size are Cryptosporidium cysts?

Answer 5

4-5um

Question 6

How long does the Cryptosporidium life cycle take to complete?

Answer 6

3-4 days

Question 7

Describe how hosts become infected with cryptosporidium

Answer 7

• Sporulated oocytes in the faeces are ingested or inhaled by neonates
• Sporocysts rupture out of the oocyst and attach themselves to the epithelial cells, in between the microvilli
• The microvilli fuse and expand around the parasite and create an outer membrane layer

Question 8

When the microvilli have fused around the parasite it is termed?

Answer 8

A trophozoite

Question 9

What happens to the trophozoite in the life cycle?

Answer 9

The parasites undergoes round one of merogony – division and amplification of merozoites
-Trophozoite => type I meront => merozoite

Question 10

Following the first round of merogony, what happens to the merozoite?

Answer 10

• Merozoites rupture out of the cell and enter the lumen to infect new epithelial cells
• second round of merogony => type II meront (sexual phase)

Question 11

Merozoites produced by the type II meront differentiate into what two cells types?

Answer 11

macrogamont and microgamont

Question 12

What happens to the macrogamont and microgamont?

Answer 12

Fuse together to form a zygote which develops into the oocyst and undergoes sporogony (division and amplification of the sporozoite)

Question 13

From the zygote, name and describe the two types of oocyst produced

Answer 13

Both contain the same number of sporozoites but one has a thick wall surrounding it (one typically found in the faeces) and one is thin walled (can rupture in the host leading to auto infection)

Question 14

Clinical symptoms of Cryptosporidium occur how many days after infection?

Answer 14

3-7

Question 15

What are the clinical signs of infection?

Answer 15

Watery, non-bloody diarrhoea, dehydration, inappetence and gastrointestinal discomfort

Question 16

How can Cryptosporidium be diagnosed?

Answer 16

• Oocyst in faeces
• Oocysts in environmental samples
• Copro-antigen test (dogs)
• Clinical signs

Question 17

How can Cryptosporidium be controlled?

Answer 17

• Control of environmental contamination
• Hygiene
• Biosecurity
• Disinfect/steam clean calf pens between batches
• Keep feeders/drinkers clean/disinfect regularly
• Disinfect clothing/hands/boots between calf pens

Question 18

Eimeria spp affect which species?

Answer 18

Lambs

Calves

Question 19

Give the general characteristics of an Eimeria life cycle

Answer 19

• Direct

- Faeco-oral transmission

Question 20

Describe the life cycle of Eimeria/Coccidiosis

Answer 20

• Lamb ingests infective sporocyst, releases sporozoites which invade gut cells, these multiply asexually to form merozoites
• Merozoites are released from ruptured gut cells
• Gametes form an oocyst which is shed in faeces

Question 21

How does an oocyst become infective?

Answer 21

Requires heat, humidity and oxygen

Sporulates which can take between 1 week and 1 year

Question 22

What are the clinical signs of a Eimeria/Coccidiosis infection?

Answer 22

Profuse diarrhoea, dehydration, inappetence, weight loss

Question 23

Unlike toxoplasma and Neospora where the sporulated oocyst contains two sporocysts with four sporozoites, Eimeria has …?

Answer 23

Four sporocysts and two sporozoites

Question 24

What are the two predator-prey hosts of Sarcocystis spp?

Answer 24

Dog-sheep

Cat-cattle

Question 25

What specifically is the infective stage for Cryptosporidium spp, Eimeria spp and Sarcocystis spp.?

Answer 25

Sporulated oocyst

Question 26

Describe the stage of differentiation of oocysts found in the faeces of calves infected with either Cryptosporidium or Eimeria and state their size.

Answer 26

Crypttosporidium oocysts are sporulated in fresh faeces and are ~4um; Eimeria oocysts are unsporulated in fresh faeces and are 20um.

Question 27

How would you diagnose a Cryptosporidium infection in calves?

Answer 27

Clinical signs of profuse watery diarrhoea, age of calves (under 6 weeks old), response to treatment, identification of oocysts in faeces using Ziehl-Neelsen stained faecal smear.