Protozoan Parasites

Question 1

protozoa general morphology

Answer 1

single celled organisms
small scale
parasitic in all vertebrate hosts
-trophozoite
-cyst/oocyst
parasitic in all host tissues/systems
variable life cycles
variable reproduction

Question 2

how do protozoa cause disease?

Answer 2

feed on solid tissues directly or after liquefying them
compete w host for ingested food
-absorb nutrients through body wall and block absorptive capacity of host GI
destroy host cells by growing in them
produce various toxic substances that aid in their ability to enter host tissues, feed, or reproduce
cause various host reactions (allergic, hyperplasia, etc)
reduce host resistance to other diseases and parasites

Question 3

intestinal flagellates

Answer 3

giardia and tritrichomonas sp

Question 4

blood-lymphatics & tissues flagellates

Answer 4

trypanosoma cruzi
leishmania sp

Question 5

intestinal coccidia

Answer 5

cryptosporidium
eimeria
isospora

Question 6

tissue coccidia

Answer 6

toxoplasma
neospora
sarcocystis

Question 7

blood coccidia

Answer 7

hepatozoon
babesia
cytauxzoon

Question 8

giardia sp

Answer 8

single cell, flagellate
primarily associated w waterborn outbreaks, daycare centers, veterinarians, travel outside of US

Question 9

giradia lifecycle

Answer 9

direct
trophozoites live free or attach via ventral sucking disk in lumen or proximal small intestine
multiply via binary fission w/ genetic diversity by allelic sequence heterogenicity
cysts passed in feces following a 7-14 incubation
host infection/reinfection via fecal oral contamination and ingestion of immediately infective cysts
symptomatic or asymptomatic

Question 10

giardia symptomatic infection dogs/ cats

Answer 10

watery diarrhea in acute phase
voluminous, malodorous stools w mushy consistency
gas, flatulence
cysts appear in stool 7-14 days post infection
clinical signs last 2-6 weeks before resolution in immunocompetent animals
-source of infection to other hosts

Question 11

giardia symptomatic infection humans

Answer 11

voluminous water diarrhea
gas, flatulence, greasy stools
abdominal discomfort, anorexia, nausea, vomiting, weight loss, fatigue
symptoms appear 7-14 days post infection
illness 2-6 weeks, self limiting if immunocompetent

Question 12

animals at risk for giardia

Answer 12

found in fecal
bias for symptomatic infections
animals at shelters, boarding kennels
multi animal situations facilitate spread from infected asymptomatic animals to susceptible hosts

Question 13

management of giardia

Answer 13

Dx: ZnSO4 floatation
-fecal taken on 3 consecutive days
-giardia SNAP in combination w fecal
-direct smear w diarrhea
supportive care to restore electrolyte balance, good plane of nutrition
bathe pet @beginning and end of treatment to remove immediately infective cysts
disinfect pet environment

Question 14

tritrichomonal blagburni

Answer 14

flagellate protoza in large intestine of cats
causative agent of chronic diarrhea
-long duration
-cats otherwise healthy (BAR, playful)
-fecal incontinence
crypt abscess, increased mucous production, erosion of colonic mucosa

Question 15

tritrichomonal blagburni risk factors and Dx

Answer 15

residence in cattery, coccidiosis as adult, < sq ft of housing
Dx: microscopically by direct smear
-differentiate from giardia
PCR specific assay
fecal culture and isolation will increase sensitivity

Question 16

tritrichomonal blagburni treatment and prevention

Answer 16

No FDA approved therapy
-impairment of DNA function by strand breakage and loss of helical function
fecal-oral transmission
no environmentally resistant cyst
trophozoites survive out of host for variable times
segregate infected cats, separate litter boxes

Question 17

tritrichomonas foetus

Answer 17

flagellate protozoa in reproductive tract of cattle
indistinguishable from other trichomonad protozoa
causative agent of bovine genital trichomoniasis
-infertility
-spontaneous abortion 1st trimester
-general repro tract infection
bulls asymptomatic and responsible for herd-level infections
-prevalence decreased w use of AI
Dx: PCR and culture

Question 18

trypansosomes

Answer 18

family members well known as causative agent of African sleep sickness and chagas disease

Question 19

trypomastigote

Answer 19

flagellate trophozoite stage circulating in blood/lymph
infective for vertebrae host\other stages are developmental in arthropod IH

Question 20

salivarian/ anterior station

Answer 20

bite infected to transmit

Question 21

sectorian/ posterior station

Answer 21

feeding bugs defecate and pass parasites

Question 22

general trypanosome lifecycle

Answer 22

arthropod IH infect during blood meal
Epimastigotes divide and multiply in IH
Develop into trypomastigotes in IH
transferred to human/ animal host
multiplication in host

Question 23

african trypanosomiasis

Answer 23

live in blood, invade lymph nodes, intracellular spaces
produce anemia from immune-mediated processes and mechanisms
-Depressed erythropoiesis
-hyperplasia bone marrow and spleen
animal production limited to areas where disease isn’t present

Question 24

trypanosoma cruzi

Answer 24

causative agent of Chaga’s disease
triatomin/ reduviid bugs obligate IH
wildlife reservoirs
trypomastigotes proliferate asexually in histocytes as amastigote stage in organisms proliferate in cardiac muscle
spread via lymphatics
disease process may be acute w death 2-4 weeks post infection

Question 25

trypanosoma cruzi vector borne transmission

Answer 25

active defecation by IH
ingestion of IH

Question 26

trypanosoma cruzi non vector borne transmission

Answer 26

blood transfusion
organ/tissue transplantation
fecal contamination

Question 27

trypanosoma cruzi genotypic variation

Answer 27

highly diverse w 6 discrete types
disease potential/response to treatment
host associations

Question 28

romana’s sign

Answer 28

edema and inflammatory response resulting from trypomastigotes defecated on host and rubbed into eye

Question 29

trypanosoma cruzi clinical

Answer 29

chronic infection
-myocardial disease
acute disease in dogs
-myocarditis, tachycardia, pale mucous membranes
Heart disease, poor prognosis
DX: serology and PCR
no effective therapeutic intervention

Question 30

leishmania sp

Answer 30

parasites infecting macrophages
amastigote stages only !!
-developmental stages occur in stage fly
-transmission by fly bite

Question 31

L. donovoni and L. infantum

Answer 31

associated with visceral disease

Question 32

L. mexicana

Answer 32

associated with muco-cutaneous disease

Question 33

L. tropica

Answer 33

associated with cutaneous disease

Question 34

leishmania sp disease in dogs

Answer 34

significant hosts for the parasite in endemic localities
severe cutaneous manifestation of disease
proliferation in visceral tissue in advanced cases
treat w antimony therapy in europe long term

Question 35

leishmania sp diagnosis in dogs

Answer 35

diagnostic PCR based protocol

Question 36

contrasting experience and approach to control

Answer 36

Europe: intensive treatment of dogs, fly protection
Brazil: sand fly surveillance, culling infected dogs, treat human cases

Question 37

differences in standard of living

Answer 37

poverty
human-animal bond
companion vs stray dog populations

Question 38

T. cruzi infection should be in differential diagnosis for dogs

Answer 38

presenting with symptoms of cardiac disease and infection
residence and travel history that includes central and south america
outdoor residence/ hunting dogs
association with kissing bugs

Question 39

Leishmania should be in differential diagnosis for dogs

Answer 39

presenting with symptoms of dermatologic disease
residence and travel history that includes central and south america and europe