Protozoans

Cystoisopora spp. (Previously Isopora)

Causes underlying mucosal damage

Apicomplexans

Asexual and

sexual reproduction (occurs in definitive host except ___)

Toxoplasma gondii

Feline definitive host

other animals are incidental (pregnant women, can enter fetus)

Infection by ingestion of oocyst (fecal-oral or undercooked meat)

Congenital toxoplasmosis (affects fetus)

Shedding of oocysts only happens limited time, may test false negative

Best ways to test for toxoplasma

Antibody test infection to prove that it was exposed

necessary because oocysts do not shed all the time (past or current)

or

Antigen test to detect current detection

Toxoplasma pathophysiology

Tachyzoite rapid intracellular reproduction

Cell death

tissue necrosis

Granulomatous inflammation

Affected sites: Liver, lung, heart, CNS, eye, fetus

Toxoplasma Transmission

Bradyzoite ingested by mammalian or avian

Sporulated oocyst in water, plants, or litter box

Transplacental or transmammary invasion by tachyzoite

Sexual reproduction only in feline, makes oocysts

Cryptosporidium spp.

Zoonotic to immunocompromised individuals

Fecal oral transmission with oocysts

Community pool, water parks

secretory diarrhea

Cryptosporidium pathophysiology

displaces microvilli of host cell

loss of surface digestion in host leads to malabsorption and then malnutrition

SPORULATED oocysts can cause autoinfection (re-infect without leaving)

Sarcocystis cruzi, hirsuta

DH- Dogs and cats

IH is the dangerous stage, ruminant equine and swine

attacks CNS muscle and organs

intraecllular

zoonotic

Sarcocystis neurona

Travels to CNS in horses

causes ataxia, weakness, muscle wasting

Opposum is DH
Equine Protozoal Myeloencephalitis

Trypanosoma cruzi

Chaga’s disease
Flagellate
Spread by Kissing bugs
3 Stages, Trypomastigote, Amastigote, Epimastigote

3 stages of Trypanosoma cruzi

Trypomastigote: extracellular, undulating membrane and whiplike tail

amastigote: intracellular, cardiac myocytes, esoph, other tissue

Epimastigote: dividing stage

Trypanosoma cruzi pathophysiology

Chronic and acute chronic inflammatory response
Cardiac Autoimmunity: causes heart failure, can take years/decades

Trypanosoma life cycle

Insect feeds on blood meal while defecating trypanosomes

enters through bite site or eye rub exposure

replicates in bite site host cells, release into blood

when in blood can reenter kissing bug

Leishmania spp.

Hemoprotozoan flagellate

effects dogs and humans, 95% fatality rate if untreated

IH sandfly

Amastigote: mammal, no flagella
Promastigote: arthropod, flagella

cause crater or volcano shaped skin lesions

Leishmania pathophysiology

many ways to avoid immune detection

prevents lysosome from consuming pathogen, and can hide in cell

delayed apoptosis

Neospora canium

Dog neuromuscular disease

IH cattle, so mostly working dogs are effected

related to toxoplasma

Oocysts, Tachyzoite, Bradyzoite

Neospora caninum pathophysiology

Granulmatous inflammation and necrosis with tachyzoite proliferation

seizures, ataxia, CNS

can cause abortions or hindlimb paralysis in dogs

Babesia canis

DH is Brown Dog Tick
Dog/Cat is IH

RBC destruction and anemia
Diagnosed by blood smear or ELISA

tick has to be attached 24-48hr to transmit disease

Cytauxzoon felis

Feline opportunistic host

DH tick by dermacentor variabilis

targets RBC and macrophages

Hepatozoon canis

Canine

Malaria like

DH tick

Meronts form in muscle tissue and other tissue

dog consumes tick, they make way to liver

Merogony: binary fission

Eimeria bovis

Coccidia

causes “scours” = diarrhea in calves

Fecal-oral spread in feedlots and indoor warm humid environment

Weight loss, bloody stool, dehydration

Prevention: calving environment, fed colostrum within 12 hours

Cryptosporidium spp.

Yellow diarrhea- cow “scours”

less seen in dogs/cat

Resist chlorine and iodine, contaminates water

*Feeder organelle steals glucose/energy from host animal

Trypanosoma brucei

“Western African Sleeping Sickness”
Hemoflagellate

Tsetse fly, cattle is a reservoir

Babesia bigemina

Opportunistic host: cattle
DH: Rhicephalus annulatus tick

Tritichomonas foetus

cattle urogenital flagellate

instestinal parasite of cats

Males symptomatic, permanently infected

females clear infection naturally

Giardia assemblage E

less common than other parasites, common in foals

Theileria equi, Babesia caballi

Intraerthrocyte

Tick transmitted: sprogony

USDA reportable disease

T. equi transplacental

Histomonas meleagridis

Infectious Enterohepatitis “Blackhead”

Flagellate and amoeboid forms

severe cecum and liver lesions

Transmission through egg of Heterakis gallinarum, fecal-oral

Haemoproteus spp

Apicomplexan

Intraerythrocytic and organ tissue

Vector transmitted, DH
Culicoides and Deer fly

Innate Immunity

Innate: Always present, non-specific

WBC: Neutrophils, Macrophages (phagocytosis), Eosinophils (Histamine), Natural Killer Cells
All secrete cytokines

Barriers: skin, mucus membranes

Acquired Immunity

Delayed but specific immunity

T helper: mediate

T cytotoxic: kill cells

B plasma cells: antibodies

Helminths

Effect of Immune System

Eliminate
Arrested State

Prevents Migration of Parasite

Parasite evasion factors

Size

Targets immature host

Overstiumlates IS

Suppress IS

Granulomas and other nodules are caused due to prolonged immune response