Protozoan Parasites Flashcards
protozoa general morphology
single celled organisms
small scale
parasitic in all vertebrate hosts
-trophozoite
-cyst/oocyst
parasitic in all host tissues/systems
variable life cycles
variable reproduction
how do protozoa cause disease?
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
intestinal flagellates
giardia and tritrichomonas sp
blood-lymphatics & tissues flagellates
trypanosoma cruzi
leishmania sp
intestinal coccidia
cryptosporidium
eimeria
isospora
tissue coccidia
toxoplasma
neospora
sarcocystis
blood coccidia
hepatozoon
babesia
cytauxzoon
giardia sp
single cell, flagellate
primarily associated w waterborn outbreaks, daycare centers, veterinarians, travel outside of US
giradia lifecycle
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
giardia symptomatic infection dogs/ cats
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
giardia symptomatic infection humans
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
animals at risk for giardia
found in fecal
bias for symptomatic infections
animals at shelters, boarding kennels
multi animal situations facilitate spread from infected asymptomatic animals to susceptible hosts
management of giardia
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
tritrichomonal blagburni
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
tritrichomonal blagburni risk factors and Dx
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
tritrichomonal blagburni treatment and prevention
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
tritrichomonas foetus
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
trypansosomes
family members well known as causative agent of African sleep sickness and chagas disease
trypomastigote
flagellate trophozoite stage circulating in blood/lymph
infective for vertebrae host\other stages are developmental in arthropod IH
salivarian/ anterior station
bite infected to transmit
sectorian/ posterior station
feeding bugs defecate and pass parasites
general trypanosome lifecycle
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
african trypanosomiasis
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
trypanosoma cruzi
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
trypanosoma cruzi vector borne transmission
active defecation by IH
ingestion of IH
trypanosoma cruzi non vector borne transmission
blood transfusion
organ/tissue transplantation
fecal contamination
trypanosoma cruzi genotypic variation
highly diverse w 6 discrete types
disease potential/response to treatment
host associations
romana’s sign
edema and inflammatory response resulting from trypomastigotes defecated on host and rubbed into eye
trypanosoma cruzi clinical
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
leishmania sp
parasites infecting macrophages
amastigote stages only !!
-developmental stages occur in stage fly
-transmission by fly bite
L. donovoni and L. infantum
associated with visceral disease
L. mexicana
associated with muco-cutaneous disease
L. tropica
associated with cutaneous disease
leishmania sp disease in dogs
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
leishmania sp diagnosis in dogs
diagnostic PCR based protocol
contrasting experience and approach to control
Europe: intensive treatment of dogs, fly protection
Brazil: sand fly surveillance, culling infected dogs, treat human cases
differences in standard of living
poverty
human-animal bond
companion vs stray dog populations
T. cruzi infection should be in differential diagnosis for dogs
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
Leishmania should be in differential diagnosis for dogs
presenting with symptoms of dermatologic disease
residence and travel history that includes central and south america and europe
