Protozoa

Define a protozoa

• a single cell eukaryote with diverse motility and that is a heterotroph (usually)

how do protozoa gain the nutrients they need?

• phagocytosis

• pinocytosis

• simple diffusion

what is the clinical relevance of protozoa performing phagocytosis

• bacteria which get phagocytosed sometimes are adapted to survive wthin the phagosome or to encyst within and survive in the protozoa → disease transmissino

Do protozoa have mouth openings?

• permanent ones in ciliates

• temporary ones in amoeba

what do we call the part that waste is released in in a protozoa?

• anal pore

why are protozoa relevant?

• some are parasitic

• some are zoonotic

give 4 examples of protozoan relevance in human medicine

1. malaria

2. amoebiasis

3. leishmaniasis

4. trichomoniasis

name 11 protozoan diseases

1. coccidiosis

2. giardiasis

3. cryptosporidiosis

4. toxoplasmosis

5. spironucleasis

6. neosporosis

7. trichomoniasis

8. babesiosis

9. trypanosomiasis

10. theileriasis

    1. hepatozoonosis

protozoan life cycle:

1. asexual or sexual

2. two most important forms

1. often both

2. cyst + trophozoite

what are the 4 morphologies of protozoa?

1. flagellates

2. ciliates

3. amoebae

4. apicomplexa

what is special about amoeboid morphology

• they change shape into flagellates in water

outline the life cycle of coccidia

1. oocysts released in faeces of a bird

2. these sporulate (become infective)

3. sporulated oocysts are consumed by other birds

4. parasites enter enterocytes and undergo asexual reproduction

5. parasites continue to multiply and infect new enterocytes

6. males and females make new oocysts

7. released in faeces

what causes disease in coccidia infections?

• the damage done to the enterocytes when they burst out from them

what symptoms do we commonly see with protozoan disease?

• diarrhoea

  • secondary bacterial infection

what do we call sporulated oocysts that develop into sexual cells?

• gametocytes

with protozoan disease, who is typically affected and why?

• young animals/those never exposed to the protozoa before

• no immunity

describe the life cycle of Eimeria bovis

1. oocyst in faeces

2. sporulates

3. ingested by host

4. invades large intestinal epithelial cells

5. asexual reproduction → pathology

6. sexual reproduction → oocyst in faeces

outline toxoplasma gondii life cycle

1. oocyst in faeces + environment

2. sporulates

3. ingested by rodent

4. asexual reproduction in rodent

5. ingested by feline

6. sexual reproduction in the feline

7. oocysts released

how do the sporulated oocysts of Toxoplasma gondii remain in the rodent?

• tachyzoites

• cysts - containing bradyzoites in the brain and muscles

Oocysts: what is their relevance? (5)

• hardy + survive in the environment

• metabolically inactive

• resistant to many disinfectants

• infectious

• may be used for diagnosis

why does the presence of oocysts in faeces not necessarily mean infection?

• some protozoa are commensals of the GIT

what is difficult about protozoan oocyst identification in faeces?

• difficult to differentiate and therefore determine whether pathogenic or not

• dirunal variation in shedding

what are 3 ways protozoa cause disease

1. toxin production

2. host immune response

3. cell + tissue damage

how does the host immune response cause damage with protozoan disease?

• hypersensitivity, inflammation

How do we diagnose protozoan disease

• trophozoite morphology

• oocyst morphology - tricky

• immune diagnosis is possible - immunofluorescence of cryptosporidium

• lesions - location + histology

why are gross lesions particularly useful in chicks to determine cause of protozoan pathology?

• location within the GIT determines the species of protozoa

what can help diagnose toxoplamosis in a cat?

• granulomas in the eye

what protozoan species affects the upper intestine of birds

Eimeria acervulina

what protozoan species affects the middile avian intestine?

• Eimeria maxima

what protozoan species affects the avian caeca

• Eimeria tenella

What protozoan species affects the avian middle intestine - large schionts, no oocysts

• Eimeria necatrix

What protozoan species affects avian rectum?

• eimeria brunetti

what are the significant species belonging to the phylum apicomplexa?

• coccidiosis

• cryptosporidiosis

• toxoplasmosis

• neosporosis

what are the 2 main coccidia species?

• Eimeria spp or Isospora species

what is the relevance of coccidiosis in poultry?

• oocyst sporulate within 24 hours of excretion + are resilient to the environment

• different species affect different locations of the gut

what birds are particularly affected by coccidiosis?

• chicks

• younger birds

• rehomed layer hens

what causes disease in birds with coccidiosis?

• direct damage to gut mucosa + secondary bacterial infections

how do we diagnose coccidiosis in poultry?

• oocysts in faeces + necropsy

what are some control measures for coccidiosis

• coccidiostats

• coccidiocides

• vaccines - live, attenduated

• BIOSECURITY/DISINFECTION

Coccidiosis in lambs:

1. main species

2. transmission method?

3. clinical signs

4. what increases chance of infection?

5. diagnosis?

6. control measures?

1. Eimeria spp - other too

2. asymptomatic adults

3. lambs - diarrhoea, dehydration, poor growth, death

4. crowded + stressful environments

5. oocysts in faeces and necropsy

6. biosecurity, disinfection, pasture rotation etc.

Cryptosporidiosis:

• mainly affects who?

• causes?

• treatment?

• transmission methods?

1. young animals

2. diarrhoea

3. none - self limiting

4. contaminated water, faeces, swimming (humans)

Toxoplasmosis:

• only definitive host is?

• I.H?

• main disease symtpom?

1. cat

2. rodent

3. abortion

what clinical signs can be seen with toxoplasmosis in:

1. sheep

2. humans

3. cats

1. abortion, still birthds, weakly lambs

2. abortion, systemic/neurological disease

3. chronic inflammatory lesions

treatment and prevention of toxoplasmosis

• combinations of pyrimethamine and a sulphonamide/spiramycin - won’t reverse already caused damage

• avoid pregnant women handling cat faeces, biosecurity and cook food thoroughly

Neosporosis:

1. important in what animal

2. definitive host?

3. what kind of transmission is relevant in the herd?

4. diagnosis?

5. treatment?

1. cattle

2. dogs

3. vertical, which maintains infection in the herd

4. abortion mid-late pregnancy

5. none

how can we prevent neosporosis?

1. dont’ allow dogs to eat the placenta

2. don’t let dogs eat raw beef

3. don’t let dogs pass faeces in fields with cattle

what are 3 relevant protozoan diseases belonging to Sarcomastigophora

1. giardiasis

2. trichomoniasis

3. histomoniasis

what feature helps us define protoza belonging to sarcomastigophora?

• amoeboid + flagellated appearance

Giardiasis:

1. definitely pathogenic?

2. zoonotic?

3. main zoonotic species?

4. found where in the environment?

5. distinguishing feature histologically?

6. how do they move

7. clinical symptom?

1. no, some are commensals

2. only some species

3. Giardia intestinalis

4. water

5. smiley face

6. falling leaf

7. diarrhoea

Trichomoniasis:

1. main species affected

2. main species of Trichomoniasis

3. transmitted how?

4. disease caused?

5. identify how?

1. birds

2. Trichomoniasis gallinae

3. via crop milk → chicks

4. severe upper GIT disease

5. diphtheritic membrane, blocking eating, drinking and respiration

Histomoniasis:

1. in what species

2. disease caused?

3. morphology?

4. I.H?

5. pathology?

6. diagnose?

7. control?

1. turkeys

2. blackhead disease

3. amoeboid + flagellated

4. earthworms

5. severe necrosis of caecae + liver

6. necropsy

7. worming + biosecurity

state two more protozoal GI diseases, not in Apicomplexa or Sarcomastigophora

1. Balantidiasis

2. Spironucleasis

Spironucleosis:

1. live where

2. transmitted how?

3. clinically?

4. species affected

5. morphology?

6. control?

7. treat? (maybe)

1. gut

2. faeces

3. diarrhoea, depression, weight loss - hole in the head

4. birds + fish

5. flagellae all directions

6. improve hygiene, less crowding

7. treat with metronidazole

Balantidium:

1. describe morphology

2. commensal?

3. species affected

4. clinical sign

5. treat?

6. prevent?

1. ciliate protozoa

2. yes

3. reptiles

4. diarrhoea

5. metronidazole (maybe)

6. BETTER HYGIENE + HUSBANDRY