Calf diarrhoea

Question 1

Calf diarrhoea affects calves of what age?

Answer 1

In the first 21 days of life

Question 2

What are the routes of transmission of pathogens causing calf diarrhoea?

Answer 2

Faecal-oral, environmental transmission (age mixing), carrier animals, fomites

Question 3

What are the sources of infection of calf diarrhoea?

Answer 3

Affected animals, asymptomatic carriers (adults and sub-acute calves), environment

Question 4

Describe the factors which can predispose calves to diarrhoea.

Answer 4

1. Exposure to ++ infectious agents
2. Failure of immunological defence mechanisms
3. Poor colostrum intake
4. Inadequate nutrition
5. Poor management = stress

Question 5

Name the pathogens associated with Calf Diarrhoea.

Answer 5

Rotavirus, Coronavirus, Cryptosporidium, Enterotoxogenic E. coli, Salmonella

Question 6

Which viral pathogen is associated with scours in calves and winter dysentery in adults? They also cause respiratory disease in cattle and humans.

Answer 6

Coronavirus

Question 7

Newbury agent is which type of virus?

Answer 7

Bovine Calicivirus

Question 8

A Torovirus which is considered zoonotic…

Answer 8

Bredavirus

Question 9

Which Cryptosporidium species is associated with neonatal diarrhoea?

Answer 9

Parvum

Question 10

Which type of stain can be used to identify cryptosporidium species?

Answer 10

ZN - shows pink crypto organisms

Question 11

Describe the life cycle of Cryptosporidium species.

Answer 11

Water containing oocysts is ingested by the host, oocysts encyst in the small intestine, asexual reproduction produces oocysts in the SI, oocysts are passed in the faeces where the sporulate (infective)

Question 12

Which species of Salmonella are important causes of calf diarrhoea?

Answer 12

Dublin, typhimurium, newport..

Question 13

Describe the morphology of E. coli ..

Answer 13

Gram -ve rod

Question 14

ETEC causes disease in which aged calves?

Answer 14

Less than 5 days old

Question 15

What clinical signs are associated with ETEC related disease in calves?

Answer 15

Acute, rapid dehydration, diarrhoea and death within 24-48 hours

Question 16

What virulence factors are used by ETEC?

Answer 16

Adhesin pili attach bacteria to host, enterotoxins cause disease.

Question 17

ETEC heat stable Enterotoxin - describe.

Answer 17

STa found in calves, causes a rise in c-GMP reduces fluid absorption.

Question 18

ETEC heat-labile enterotoxin

Answer 18

LT - inhibits Na+(Cl- and H2O) absorption in villus cells and stimulates Na+ secretion in crypt cells - remember secretion is also regulated by calmodulin

Question 19

Pathogenesis of ETEC?

Answer 19

Penetrates intestinal mucosa and enterotoxin causes secretion and reduced absorption of Na+, Cl- and H2O (increased osmotic gradient), profuse liquid faeces, rapid and severe dehydration, shock, high mortality.

Question 20

Which other E. coli types are associated with calf diarrhoea?

Answer 20

Attaching and effacing, enteropathogenic, verocytotoxogenic

Question 21

Which pathogens causing calf diarrhoea are associated with a) 0-6 days calves and b) 6+ days calves?

Answer 21

a) ETEC

b) Rotavirus, coronavirus, cryptosporidium

Question 22

What is the pathophysiological mechanism of calf diarrhoea?

Answer 22

Hypersecretion - enterotoxins (diarrhoea)
Malabsorption - due to villous damage, decreased lactase activity, partial digestion – fermentation (acid production) - metabolic acidosis

Question 23

Which pathogens cause hypersecretion diarrhoea?

Answer 23

ETEC, cholera

Question 24

Which pathogens cause malabsorption diarrhoea?

Answer 24

Viruses, crypto