Eimeria Flashcards
What needs to be considered when thinking about poultry parasites in indoor vs outdoor reared birds?
- Far less control over birds reared outdoors compared to in
- Less biosecurity
Describe the management of broilers with Eimeria
Live for 6-7 weeks only – naïve, highly susceptible and vulnerable to exposure. Eimeria spp infection is major problem/constraint on productivity
Describe the management of layers with Eimeria
Adult female birds, by time they reach maturity should have immunity through exposure
What can act as a reservoir for parasites, transmitting them to free range birds?
Wild birds
What is the most important protozoal disease of livestock?
Coccidiosis
What are 2 coccidiosis spp examples?
Eimeria
Isospora
What is the optimal condition for Eimeria parasite survival?
- Under intensification, facilitating passive spread of parasites by faeco-oral route
- Warm, moist conditions – enabling rapid and successful sporulation of oocysts
How many of the 7 poultry Eimeria spp are considered to be highly pathogenic?
3
What is the infective stage of Eimeria spp?
Sporulated oocyst
Describe an Eimeria sporulated oocyst
Each sporulated oocyst has 4 sporocyst each of which has two sporozoites (8 sporozoites in total)
Describe the life cycle of Eimeria tenella inside the host
- 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
Describe the life cycle of Eimeria tenella in the environment
- 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
Which factors affect the epidemiology of Eimeria
- 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)
How is Eimeria diagnosed?
- Clinical signs (diarrhoea +/- blood, life listless chickens, death)
- PM exam (appearance of parasite stages: schizonts and merozoites)
- Drop in food conversion rate (subclinical infections)
Describe the pathogenesis of Eimeria
- 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
Which drug is used for prophylactic control of Eimeria
Ionophores
What is the aim of Eimeria control in broilers?
Aim to eliminate disease and optimise growth and feed conversion rate
- Lifetime in feed prophylaxis, from hatching to withdrawal
What is the aim of Eimeria control in layers?
Aim to allow immunity to develop
• Step down programmes
• Drug of low efficacy
• Sub-efficacious levels
How else is Eimeria controlled?
- Hygiene to prevent contamination with high numbers of oocysts
- Vaccination (paracox)
Which drug is used to treat Eimeria?
Toltrazuril ‘Baycox’
How are Isospora oocysts different to Eimeria?
2 sporocysts each with 4 sporozoites
Describe Coccidiosis in sheep, including the clinical signs
- Disease in young lambs (2-3 months)
- Caecum and colon infected
- Clinical signs: Diarrhoea, dehydration, abdominal pain, anorexia
Describe Coccidiosis in cattle, including the clinical signs
- Usually affects cattle < 1yr old
- Housed animals, older animals
- Caecum and colon infected
- Clinical signs: Dysentery (diarrhoea containing blood or mucus), diarrhoea, dehydration
Describe Coccidiosis in Pigs, including the clinical signs
- Very young piglets
- Infect small intestine (unlike the LI in cattle and sheep), 2 sporocysts with 4 sporozoites
- High morbidity, low mortality
- Diagnosis difficult
