Eimeria

Question 1

What needs to be considered when thinking about poultry parasites in indoor vs outdoor reared birds?

Answer 1

• Far less control over birds reared outdoors compared to in
• Less biosecurity

Question 2

Describe the management of broilers with Eimeria

Answer 2

Live for 6-7 weeks only – naïve, highly susceptible and vulnerable to exposure. Eimeria spp infection is major problem/constraint on productivity

Question 3

Describe the management of layers with Eimeria

Answer 3

Adult female birds, by time they reach maturity should have immunity through exposure

Question 4

What can act as a reservoir for parasites, transmitting them to free range birds?

Answer 4

Wild birds

Question 5

What is the most important protozoal disease of livestock?

Answer 5

Coccidiosis

Question 6

What are 2 coccidiosis spp examples?

Answer 6

Eimeria

Isospora

Question 7

What is the optimal condition for Eimeria parasite survival?

Answer 7

• Under intensification, facilitating passive spread of parasites by faeco-oral route
• Warm, moist conditions – enabling rapid and successful sporulation of oocysts

Question 8

How many of the 7 poultry Eimeria spp are considered to be highly pathogenic?

Answer 8

3

Question 9

What is the infective stage of Eimeria spp?

Answer 9

Sporulated oocyst

Question 10

Describe an Eimeria sporulated oocyst

Answer 10

Each sporulated oocyst has 4 sporocyst each of which has two sporozoites (8 sporozoites in total)

Question 11

Describe the life cycle of Eimeria tenella inside the host

Answer 11

• Direct, Faeco-oral
• Schizont is full of merozoites which go on to infect more caecal epithelial cells -> get mass replication through asexual reproduction
• Female = macrogamete and Male = microgamete are involved in sexual reproduction
• The whole life cycle is around 7days

Question 12

Describe the life cycle of Eimeria tenella in the environment

Answer 12

• Zygote is passed out in faeces (unsporulated oocyst)
• Over 1-2 days the unsporulated oocyst undergoes sporogony and becomes sporulated
• It is now infective and is ingested by the host

Question 13

Which factors affect the epidemiology of Eimeria

Answer 13

• Parasite (survival of oocysts in environment, low numbers persist in housing as impractical to completely remove)
• Host (naïve, susceptible young – day old chicks)
• Immunity (good immunity follows natural infection)
• Environmental conditions (intensive husbandry, can provide ideal conditions for sporulation and oocyst survival)

Question 14

How is Eimeria diagnosed?

Answer 14

• Clinical signs (diarrhoea +/- blood, life listless chickens, death)
• PM exam (appearance of parasite stages: schizonts and merozoites)
• Drop in food conversion rate (subclinical infections)

Question 15

Describe the pathogenesis of Eimeria

Answer 15

• Severity of disease related to parasite density – high level of exposure results in more severe disease
• Damage to epithelial cells
• Heavy infections: haemorrhage (depends on species causing infection)
• Lighter infections: impairs absorptive capacity of gut

Question 16

Which drug is used for prophylactic control of Eimeria

Answer 16

Ionophores

Question 17

What is the aim of Eimeria control in broilers?

Answer 17

Aim to eliminate disease and optimise growth and feed conversion rate
- Lifetime in feed prophylaxis, from hatching to withdrawal

Question 18

What is the aim of Eimeria control in layers?

Answer 18

Aim to allow immunity to develop
• Step down programmes
• Drug of low efficacy
• Sub-efficacious levels

Question 19

How else is Eimeria controlled?

Answer 19

• Hygiene to prevent contamination with high numbers of oocysts
• Vaccination (paracox)

Question 20

Which drug is used to treat Eimeria?

Answer 20

Toltrazuril ‘Baycox’

Question 21

How are Isospora oocysts different to Eimeria?

Answer 21

2 sporocysts each with 4 sporozoites

Question 22

Describe Coccidiosis in sheep, including the clinical signs

Answer 22

• Disease in young lambs (2-3 months)
• Caecum and colon infected
• Clinical signs: Diarrhoea, dehydration, abdominal pain, anorexia

Question 23

Describe Coccidiosis in cattle, including the clinical signs

Answer 23

• Usually affects cattle < 1yr old
• Housed animals, older animals
• Caecum and colon infected
• Clinical signs: Dysentery (diarrhoea containing blood or mucus), diarrhoea, dehydration

Question 24

Describe Coccidiosis in Pigs, including the clinical signs

Answer 24

• Very young piglets
• Infect small intestine (unlike the LI in cattle and sheep), 2 sporocysts with 4 sporozoites
• High morbidity, low mortality
• Diagnosis difficult

Question 25

Describe Coccidiosis in rabbits, including the clinical signs

Answer 25

• Wasting, diarrhoea, jaundice

- Epithelium of bile ducts -> enlarged liver, white nodules