bacterial and parasitic persisters TUESDAY 11/3

bacterial persisters to know:

• brucella abortus

• chlamydia abortus

• coxiella burnetii (q fever)

• mycobacterium avium subsp. paratuberculosis (johne’s)

• salmonella enterica subsp. enterica serotype dublin

which bacterial persistors are G-?

all of them (b. abortus; c. abortus, c. burnetii, salmonella enterica…) except mycobacterium, which is acid-fast

bacterial persisters that shed through birthing material:

b. abortus (also milk), c. abortus, c. burnetii (also feces, urine)

bacterial persistors that shed through feces

mycobacterium (also mammary secretions) and salmonella

bacterial persistors that are facult. intracellular:

b. abortus, mycobacterium and salmonella

bac. persisters that are obligate intracellular

c. abortus and c. burnetii

b. abortus and chlamydia abortus cause what dz in the reservoir?

primiparous abortion

c. burnetii causes what dz in reservoir?

abortion - any parity

mycobacterium causes what dz. in reservoir?

chronic diarrhea w malabsorption / wasting

salmonella causes

septicemia (sepsis) especially w embolic spread to lung (interstitial pnuemonia)

these bac have a bovine reservoir

b. abortus, mycobacterium, and salmonella (adults shed, calf gets dz)

ovine reservoir

c. abortus and c. burnetii (also ovine reservoir)

short environmental bacterial persisters

b. abortus and c. abortus

which bac persister lasts months to years on surfaces (bacterial persister)

salmonella

(4-7 months in soil)

long lasting bacterial persisters

c. burnetii and mycobacterium - both depending on surface

effective vx for these bacterial persisters?

b. abortus (vx F cattle); c abortus (vx F sheep - marginal shed reduction)

no vx for these persisters:

c. burnetii (in US); mycobacterium; salmonella has vx but ineffective!

bac persistors that remove birthin material for biosecurity prevention/control

c. abortus and c. burnetii

bac persistors that use culling to improve biosecurity

b abortus, mycobacteriu, and salmonella

protozoan examples:

giardia (a diplomonad); tritrichomonas (a trichomonad); cystoisospora and eimeria (apicomplexans / coccidia)

taxonomy of giardia

a flagellated protozoan

• worldwide dist.

• in small intestine

• direct life cycle

giardia morphology

• trophozoites in small intestine

• cysts are closer to external environment, giardia form cysts to protect themselves, very HARDY

  • no replication in cysts

giardia diagnostic tests

• immunofluorescent assays - (giardia cysts & cryptosporidium cysts go GREEN)

  • done regularly in lab

• wet mount - mix stool + saline, look for motile trophozoites

• centrifugal flotation - finds cysts (need sugar solution - salt too high SpG)

• immunodiagnostics like ELISA

  • swab STOOL

challenges with diagnosing giardia:

• intermittent shedding - repeat testing good

• often confused w/ other stuff (bc small and refractile)

• low sensitivity in wet mounts

• persistent detection of cyst wall antigen in chronically infected asymp adult dogs

giardia infective stages

cysts! are infective

giardia diagnostic stages

both trophozoites and cysts can be diagnosed, but only cysts are infectious bc trophozoites don’t survive in the enviro

how is giardia transmitted?

through ingestion of cysts

• very prevalent in small animals

what is a prepatent period?

the time from ingestion of cysts to shedding cysts in feces (for giardia)

clinical signs of giardia caused by (which stage)

trophozoites caused clin signs

• attach → blunt intestinal villi → maldigestion, malabsorption, diarrhea

clinical signs of giardia are highly variable, and can be asymptomatic or can include

• chronic/pasty diarrhea (could also be normal school), wt loss

• lethargy, farting

• failure to thrive, impacts on growth

• +/- dry skin, poor haircoat

protocols for prevention and control of giardia

• avoid contact w contaminated water/food sources

• utilize disinfectants where possible

• bathe them once treated (cysts sometimes on fur, can reingest when grooming)

giardia has different __ which means when both animals and humans are infected in the same house, it does not necessarily imply zoonotic transmission

_ assemblages _ (diff assemblages in diff species probably)

tritrichomonas blagburni: what to know

• “trich”

• casuses GI dz in small animals, devastating dz and repro dz in herd animals

• no hardy enviro form, ONLY trophozoites

cystoisospora and eimeria are

apicomplexans (“coccidia”)

• pretty hardy in environment (pick up poop before oocysts sporulate and become infectious!)

apicomplexan life cycles always include a phase called “__”

“sporogony”

• oocysts produced → sporogony → sporulate

• sporogny happens in environment (unsporulated oocyst exits host)

• becomes infectious after sporulation (needs time and conditions)

a platyhelminth is a type of helminth/worm characterized by

dorsoventrally flattened body

a trematode is a type of platyhelminth, known as a __

_ fluke _

fasciola hepatica lives WHERE in the host?

in the liver/bile ducts

(“common liver fluke”)

hosts for f. hepatica:

common in herbivores (cattle, sheep, goats, rums, horses, pigs)

diagnosis of flukes/trematodes uses

sedimentation (can use the “fluke finder”)

• can find fluke eggs bc heavy stuff sinks

can +/- use ELISA, slaughter data, seasonal occurrence, previous history, knowledge of snail habitat, and liver enzyme tests

important intermediate host for f. hepatica:

snail (important intermediate host)

morphology of f. hepatica

~1 cm long and leaf-like appearance

• microscopic spines

• ORAL SUCKER

f. hepatica form that penetrates snail host:

miracidium (ciliated motile form comes out of egg, moves through water looks for snail)

• (egg leave liver of definitive host through bile ducts, travel thru SI, leave in stool)

in the snail, f hepatica goes from miracidium to…

…sporocyst, rediae, then cercariae

motile cercariae of f. hepatica leave snail and then…

…encyst on grass and form infective metacercariae (6 wks to months)

infective stage of f. hepatica is

metacercariae stage

diagnostic stage of f. hepatica

diagnostic stage is the eggs that leave in stool

• sedimentate stool to find eggs

what intermediate host does the f. hepatica trematode use?

lymnae spp. snails are the IH

is f. hepatica zoonotic?

yes, it is zoonotic

• also, has indirect life cycle

• is a platyhelminth

f. hepatica and f. gigantica have ___ periods as well

_ prepatent _

(weeks in fasciola)

clinical signs of fasciola

• hepatomegaly (enlarged liver)

• ANEMIA!!!

• sudden death (depends on host)

• biliary obstruction and inflammation, fibrotic changes over time

• ascities, bottle jaw (submandib edema), emaciation

fasciola causes ___ signs in cattle and __ signs in sheep

_ chronic_ and _acute_

chronic signs of fasciola in cattle

• gradual wt loss, poor feed conversion, constipation

• +/- anemia in calves

• sometimes aberrant migration to lungs (cattle)

acute signs of fasciola in sheep

• bloody nasal discharge, anemia, sudden death

• associated w black’s disease (sheep)

treatment of fasciola

• parziquantel (a common platyhelminth drug, used for tapeworms too)

• albendazole (another drug)

• avoid eating veg w metacercariae

• kill snails in habitate

• rotate pastures (reservoir hosts maintain pasture contamination)

comparing impact of environment (giardia vs trichomonads vs coccidia vs fasciola)

• giardia: persistance of cysts in direct life cycle

• trich: fragility of trophozoite (only stage)

• coccidia: oocyst development - sporulate in enviro

• fasciola: prevalence related to IH population (snails)

coccidian life cycles steps:

1. sporulated oocyst enters gut (has motile organisms in oocyst)

2. motile organisms released and start replicating

3. complete asexual reproduction (2nd round)

4. cells filled with asexual stages burst → find new cells to inhabit → more rounds of asex rep before making M and F

5. then you have M and F sexual stages that make oocysts

6. oocysts leave gut and reinfect next host

important details of coccidian life cycle as they relate to healthy animals:

coccidia is self-limiting, so in healthy animals eventually the coccidian life cycle will stop and the oocysts will be shed out

cytoisospora overview

• an apicomplexan, commonly called “coccidia”

• SMALL INTESTINE

life cycle of coccidia

1. merogony/schizogony = asexual phase

• form invasive, motile forms

2. gamogeny/gametogony = sex phase & gamete production

• form oocyst

3. sporogony = sporulation

• dev of oocyst to infectivity

merogony/schizogony of a coccidian life cycle is…

…asexual, and forms invasive, motile forms

gamogony/gametogony in the life cycle of a coccidian is the…

…sexual phase with gamete production, and includes formation of the oocyst

sporogony in the life cycle of a coccidia is…

…sporulation and development of the oocyst to infectivity

cystoisospora and eimeria need to sporulate…

…in order to be infectious (as opposed to cryptosporidium, an apicomplexan that is shed already infectious bc sporulates endogenously)

a different depiction of the coccidian life cycle

consider: how time since infection change what is found on fecal examination

• pre patent period might lead to false negatives in a sick animal

in the asexual phase of coccidia…

…the cell fills with high numbers of the organism and then burst (oh no!)

what is used to identify the various species of coccidia (crystoisospora spp.)?

sporulated oocyts are usually used to ID the various spp.

coccidia infections are more common in (what age group)?

more common in young animals!

cystoisospora are host specific or not host specific?

cystoisospora spp. are highly host specific!

prevalence of cystoisospora in dogs in north america:

prevalence ranges from 3% to 38%

clinical signs of coccidiosis include

• diarrhea w/ wt loss

• dehydration

• +- hemorrhage (and/or bloody diarrhea)

• severely affected animals may present w anorexia, vomiting, depression

treatment for coccidiosis

sulfadimethoxine is ONLY drug label approved for enteritis associated w/ coccidiosis

• among newer drugs, ponazuril appears to be effective

control considerations for coccidia

• once infective, oocysts are resistant to most disinfectants

• pressure wash kennels, seal floors

• pick up poop before sporulates!

flukes (trematodes) we have discussed

• fasciola sp.

• paragonimus sp.

tapeworms (cestodes) we have discussed:

• diphyllobothrium sp. → marine life cycle, pi

• echinococcus spp. and taenia spp. → scavenging/predation