Parasitology - Mammalian Coccidiosis Flashcards Preview

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Flashcards in Parasitology - Mammalian Coccidiosis Deck (25):
1

Many species of Eimeria that cause coccidiosis in mammals are:

A. Highly pathogenic

B. Moderately pathogenic

C. Have low pathogenicity

D. Completely harmless

C. 

Many species are of little pathogenic importance and high faecal oocyst counts may be found in healthy animals.

2

Coccidia of cattle:

There are many species but few are of pathological significance in the UK. 

Calves less than a year old are sporadically affected.

PPP is 2-3 weeks

What are the two main Eimeria species that cause cocciodiosis in the UK, what are their sites of infection and characteristics of their life cycles?

E. bovis
- most common
- big oocysts 28x20 μm

Sites of infection: Central lacteal of small-intestinal villi & epithelial cells of caecum & colon

 

E. zuernii

- most pathogenic - more blood, morbidity & mortality
- blood-stained dysentery & sloughed mucosa
- spherical oocysts 16 μm

Sites of infection: Connective-tissue cells of lamina propria in lower small intestine & epithelial cells of caecum & colon

 

3

What would you use to vaccinate a herd of cattle against coccidiosis caused by Eimeria spp?

Nothing. There are no vaccines available.

4

What are the clinical signs of bovine coccidiosis?

Haemorrhagic typhlocolitis ie., diarrhoea with pieces of mucosa; bloody diarrhoea
- blood found primarily in large intestine
- continuous need to defecate
- can lead to anal prolapse
- dehydration, anaemia, fever

5

What are the main Eimeria species that cause cocciodiosis in sheep?

E. ovinoidalis & E. crandalis

6

Under the microscope, what are the most distinctive feature of Eimeria infection in sheep? 

Giant schizonts (macromeronts) visible as white spots
 

7

What age of sheep is most susceptibe to coccidial infection?

Lambs ~6 weeks old in mixed groups, esp. twins & triplets

8

Where are the sites of infection in the lamb by Eimeria species?

Caecum & colon epithelial cells

9

Why does coccidia in sheep have "enzootic stability"? What does this mean and how can this spread infection? 

Ewes are immune carriers, so they contaminate litter, outdoor water & food troughs with oocysts

Early lambs amplify parasite population, later lambs under pressure

However, many lambs with high faecal oocyst counts die before shedding oocysts

10

What are the two Eimeria species OF IMPORTANCE that cause coccidia in goats? What are the clinical signs of goat coccidia? What are the sites of infection?

E. ninakohlyakimovae (problem in Portugal)
E. arloingi

Clinical signs:

- Diarrhoea

- High mortality & morbidity

- Growth rate retardation

Sites of infection:

Same as Eimeria species in lambs: Caecum and colon epithelial cells

11

What is the main Eimeria species that causes coccidia in horses? What is its site of infection and what are the clinical signs of disease?

Eimeria leuckarti

Site of infection: 

Small intestine - invaded by large gametocytes in subepithelia

Clinical signs:

- occasional diarrhoea

- weight loss

- anorexia

- dehydration

12

What is different about the horse's Eimeria leuckarti oocyst and its PPP?

Oocyst is 70 x 53 μm, big & dark, thick oocyst wall

PPP =up to 15 weeks!

13

What does it mean that E. leuckarti is less immunogenic in the horse than other Eimeria species in other animals?

Infection doesn’t cause development of immunity in affected foals.

14

What is the most important protozoan that causes coccidiosis in pigs? What is the site of infection and what is the disease? How serious is it?

Isospora suis

Site of infection: Small intestine mucosa (can move to caecum & colon in severe conditions)

Clinical: Profuse diarrhoea, can be fatal

15

What is the protozoans that causes coccidiosis in dogs and what are the most important species names? What are the sites of infection, and how serious is it? 

Protozoa: Isospora & Neospora

Species: Isospora canis, Neospora caninum

Sites of infection: Small intestine

Low pathogenicity: Only occasionally causes disease, so look for other causes of diarrhoea even if faecal oocyst count is high.
 

16

What are the differences between the oocysts of Isospora canis and Neospora caninum, which cause canine coccidiosis?

I. canis oocysts are about 60 µm while N. caninum oocysts are only 25-30 µm.

17

Unlike other protozoan species that cause coccidiosis, Isospora felis of cats has a facultative heteroxenous life cycle. What does that mean?

The protozoan has “choice” of going through wide range of intermediate hosts (rodents, ruminants) in which it can stay in dormant dormozoite state.

18

What is important about the Isospora felis oocyst in terms of diagnosis?


The oocysts are used to distinguish the protozoan infection from other protozoan invaders such as  Toxoplasma gondii & Sarcocystis spp.

The I. felis oocyst is much bigger (about 66 μm) than those of Toxoplasma gondii & Sarcocystis spp

19

What are the Eimeria species that cause coccidiosis in rabbits? What are the sites of infection, and how serious is the disease?

Eimeria flavascens

Eimeria intestinalis

Site of infection: caecum

Intestinal coccidiosis:
- mucoid diarrhoea, sometimes haemorrhagic 

- flatulence

- dehydration

- low appetite

High mortality in cases of severe enteritis

20

What type of preventative regimen would you recommend against coccidial infection in calves?

1. Improve management & hygiene/sanitation; increase bedding, raise water & feed troughs to avoid faecal contamination

2. Preventative in-feed anticoccidial drugs:
decoquinate

3. Injectable antiprotozoals eg. sulphamethoxypyridazine might limit oocyst production

4. Orally administered coccidiostats: Toltrazuril (Baycox® 5 % Susp., Bayer Health Care); Diclazuril (Vecoxan® 0,25 % Susp., Janssen Animal Health)

5. Move animals to clean environment

21

What type of preventative regimen would you recommend against coccidial infection in sheep?

1. Improve management, avoid overcrowding & stress

2. Improve hygiene, dag ewes

3. Avoid mixing lambs of different ages

4. Prevent infection by creep-feeding lambs
with decoquinate
or oral dosing with diclazuril when lambs are 4-6 weeks. Second dose after three weeks.

22

What type of preventative regimen would you recommend against coccidial infection in dogs?

Toltrazuril (Baycox® 5% suspension) p.o.

23

What type of preventative regimen would you recommend against coccidial infection in rabbits?

1. Suitable drugs in drinking water:
Sulfaquinoxalin
Sulfadimethoxin - over 3-5 days, then repeat treatment
Toltrazuril

2. Medicated food can be used in commercial
units

24

How would you diagnose Eimeria species in a live rabbit?

Float oocysts in salt solution to identify species

25

Why is it difficult to diagnose coccidiosis in pigs while they're alive AND after they're dead?

- Diagnosis difficult ante-mortem because diarrhoea starts before oocysts shed in faeces.


- Difficult @ post mortem because death typically occurs after parasites have left body (it’s self-limiting, like Eimeria)

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