protists Flashcards
what are protozoa
single celled eukaryotic organisms that feed heterotrophically and have diverse motility mechanisms
how do protists feed
- phagocytosis, pinocytosis or simple absorption
- mouth opening may be temporary (amoeba) or permanent (ciliates)
- food particles surrounded by membranes forming a food vacuole, digestive enzymes secreted into vacuole
- soluble nutrients are absorbed into endoplasm, waste discharges through opening in plasma membrane
list important veterinary protists that are zoonotic
- giardiasis
- cryptosporidiosis
- toxoplasmosis
- babesiosis
- trypanosomiasis
what is a trophozoite
feeding form of a protist
outline reproduction in protozoa
- often have complex lifecycles with different stages in the same ot different hosts
- asexual stages include mitotic division of parent cell into 2 or more identical offspring
- sexual reproduction = formation and fusion of gametes producing new offspring
outline the life cycle of coccidia
outline the lifecycle of toxoplasma gondii
what is an oocyst
“egg” form of a protist
- hardy and survive in the environment
- metabolically inactive so cant be hit by drugs
- resistant to many disinfectants
- infectious (but not always immediately)
- may be detected in feces and used for diagnosis
how do protozoa cause disease
- compete with normal commensals changing gut microbiota
- produce toxins
- cause host immune response (major reason)
- damage cells and tiussues (major)
how do you diagnose protozoa
- look at trophozoite morphology
- oocyst morphology
- may be detected in feces
- gross and/or histopathological observation of lesions
different spp of eimeria can be dx’d by where in GIT they affect
list GI protozoal diseases
- coccidiosis
- cryptosporidiosis
- toxoplasmosis
- neosporosis
- giardiasis
- trichomoniasis
- histomoniasis
- balantidiasis
- spironucleasis
what are the most important genera of coccidiosis
eimeria spp or isospora spp
discuss coccidiosis infection in poultry
- oocysts sporulate within 24hrs of excretion and are resilient in environment (can survive years)
- different sp infect different parts of gut and cause different clinical signs (diarrhea, poor growth and death often seen)
- disease is due to direct damage to gut mucosa and secondary bacterial infections
- big issue in young birds and rehomed layer hens (no immunity after living in strict biosecurity conditions)
- diagnose via oocysts in feces and necropsy
how is coccidiosis diagnosed and controlled in birds
- Diagnosis – oocysts in faeces and necropsy
- Control measures include: coccidiostats, coccidiocides, vaccines (live, attenuated), biosecurity/disinfection
discuss coccidiosis in lambs
- mainly eimeria spp
- adults act as asymptomatic sources of infection to young animals
- lambs under 6 months get diarrhea, dehydration, poor growth and death
- particularly issue in crowded and stressful conditions
how is coccidia diagnosed/controlled in lambs
- Diagnosis – oocysts in faeces (but not necessarily very useful as can have high counts without disease and low counts with disease) and necropsy
- Control measures include: coccidiostats, coccidiocides, biosecurity / disinfection / rotation of pasture etc, ensure get colostrum
outline the lifecycle of cryptosporidiosis
which strain of cryptosporidiosis is zoonotic
C. parvum
how is crypto controlled/treated
- no treatment for non-human animals as is self limiting
- no vaccine
outline the lifecycle of toxoplasmosis
what is the definitivie host for toxoplasmosis
cats - dont show disease
oocysts are mainly shed by younger cats
what is the intermediate host of toxoplasmosis
rodents - get tissue cysts which are eaten by cats
can transmit vertically
disease of toxoplasmosis in accidental hosts manifests as
sheep: abortion, stillbirths or weakly lambs
humans: abortion, systemic/neurologic disease
outline the life cycle of neosporosis
