Systemic Apicomplexans - NCSU Veterinary Parasitology · Systemic Apicomplexans Toxoplasma gondii....
Transcript of Systemic Apicomplexans - NCSU Veterinary Parasitology · Systemic Apicomplexans Toxoplasma gondii....
Protozoan Groups
Flagellates
HemoflagellatesTrypanosoma cruziLeishmania infantum
MucoflagellatesTritrichomonas foetusGiardia spp.
Apicomplexans
Intestinal ApicomplexansCryptosporidium parvumEimeria spp.Cystoisospora spp.
Systemic ApicomplexansToxoplasma gondiiNeospora caninumSarcocystis cruzi, S. neurona
Blood ApicomplexansBabesia bigemina,Babesia canis, B. gibsoniCytauxzoon felis
Ciliates
Balantidium coli
Amoeba
Entameoba histolytica
Historically, protozoa have been grouped by mode of motility.
Toxoplasma gondii
Feline coccidian of zoonotic importancehttps://medicalxpress.com/news/2014-07-toxoplasma-gondii-cancer-tracks-vaccine.html
https://www.cdc.gov/dpdx/toxoplasmosis/index.html
Toxoplasma
Morphology
Oocyst small, sub-spherical, smooth coat, no polar cap,
single embryo when passed = unsporulated Sporulated oocyst contains 2 sporocysts with 4
sporozoites each = 8 sporozoites total
https://www.cdc.gov/dpdx/toxoplasmosis/index.html
Toxoplasma
Complex Life CycleCat to Cat
Direct Life Cycle (homoxenous) Definitive host – Felids only
Transmission -- fecal-oral, ingestion of oocyst Invasion -- Sporozoites excyst from oocyst and invade
enterocyte Asexual reproduction (in intestinal cells)
Endodyogeny [single division forming 2 daughter cells] andSchizogony [multi-nuclear division followed by cytoplasmic division forming multiple daughter cells]
Approximately 5 cycles of endodyogeny and / or schizogony Causes none to mild pathology in the cat. Some sporozoites invade deep tissues multiply & disseminate as
tachyzoites, but eventually form bradyzoite cysts
Toxoplasma
Complex Life Cyclein Cat
Sexual reproduction (only occurs in the Felids) Gametogony, Fertilization, Oocyst
Dissemination Oocysts (unsporulated) exit the host in the feces and
contaminate the environment. Felids are the only hosts to pass oocysts. Felids usually only shed oocysts once in their life time Prepatent period (oocyst ingestion to oocyst passing): 19
- 48 days Oocysts highly resistant and remain infectious for many
months
Toxoplasma
Complex Life Cycle
Paratenic Host to Cat
Facultative Indirect Life Cycle (heteroxenous) Paratenic host – Any warm blooded animal Cat ingests a tissue cyst from a paratenic host =
carnivorism Bradyziotes released from tissue cysts develop into
tachyziotes. The rest of life cycle follows that of “Cat to Cat”
Asexual Cycle in Intestinal epithelium Sexual Stage resulting in an unsporulated oocyst, being passed in the
feces. As well as invasion of deep tissues to form bradyzoite cysts
Toxoplasma
Complex Life Cycle
Cat to Paratenic Host Facultative Indirect Life Cycle (heteroxenous)
Paratenic host – Any warm blooded animal, including felids
Transmission Paratenic host ingests an oocyst from the feces of a
felid Invasion -- “Zoites” enter intestinal cells and
lymph cells and transform into tachyzoites. Tachyzoites - rapidly dividing zoites via endodyogeny
(2 daughter cells / division)
Toxoplasma
Complex Life Cycle
in Paratenic Host
Asexual reproduction – extra-intestinal cells Tachyzoites are invade deep tissues and disperse throughout the
body of the paratenic host The rapid destruction of host cells during the tachyzoite phase
causes the acute / severe disease Eventually tachyzoites transform into bradyzoites
Bradyzoites Slowly dividing zoites via endodyogeny (2 daughter cells / division) Stationary (= non-disseminating) and form tissue cysts.
Tissue cysts Cause more chronic pathology in the paratenic (and human) hosts Occur in and cause damage to the brain, liver, lungs, striated muscles. Remain viable for the life of the paratenic host.
Toxoplasma
Complex Life Cycle
in Paratenic Host
General Notes Tachyzoites may be transplacentally transmitted. Mother’s ingestion of oocyst from cat feces could
lead to Toxoplasmosis in fetus
Toxoplasma
Complex Life CycleParatenic Host to Paratenic Host
Transmission ingestion of a tissue cyst from a paratenic host =
carnivorism Bradyziotes released from tissue cysts develop into
tachyziotes. Invasion and Asexual reproduction is the same
as “Cat to Paratenic Host” above General Notes
Tachyzoites may be transplacentally transmitted. Mother’s ingestion of raw meat with tissue cysts may lead to
Toxoplasmosis in the fetus
Toxoplasma
Pathology
Intestinal Phase in Felids -- minimal.
Systemic Disease (Extra-Intestinal Phase) in felids or paratenic hosts or humans Explosive replication of tachyzoites causes massive
destruction of host cells, also acute immune response. Most often affects brain, liver, lungs and striated
muscles. Tissue cysts cause physical cell/tissue damage, and are
a source for latent disease.
Toxoplasma
Clinical Disease - Cat Only
Intestinal Disease – no complaint Oocysts noticed on routine fecal
Systemic Disease - Non-specific disease: Fever, anorexia, vomiting,
diarrhea, enlarged lymph nodes, pneumonia (especially for FIV+ cats), encephalitis, nephritis, death.
Toxoplasma
Diagnosis - Cat only Intestinal Disease
Oocysts in feces Fecal float centrifugation Use Zinc Sulfate as oocysts may distort in other solutions
Systemic Disease Serologic tests – IgG and IgM antibodies. Thoracic radiographs if lung involvement Definitive diagnosis – detection of tachyzoites in
effusions, tissue aspirates or biopsy samples.
Toxoplasma
DiagnosisFecal Float Centrifugation
Toxoplasma
https://www.cdc.gov/dpdx/toxoplasmosis/index.html
http://people.upei.ca/sgreenwood/html/protozoa.html
DiagnosisAspirates or Necropsy
Toxoplasma
https://www.cdc.gov/dpdx/toxoplasmosis/index.html
Tachyzoites from Effusion or Aspirate Bradyzoite cyst from
Necropsy / Histology
https://www.cdc.gov/dpdx/toxoplasmosis/index.html
Treatment - Cat only
Intestinal Disease Pyrimethamine plus triple sulfa drugs used against
intestinal phase and acute phase. Clindamycin and Ponazuril also used.
Systemic Disease Clindamycin for at least 4 weeks (12.5mg/kg twice
daily). Supportive treatment depending on clinical signs –
oxygen for dyspnea, assisted feeding for anorexia.
Toxoplasma
Control - Cat only
Sanitation Clean litter box daily (sporulation in 1-3 days).
No raw meat for cats Don’t let cat outside to defecate or hunt
Toxoplasma
Non-felid paratenic hosts Dogs
Systemic toxoplasmosis, ingest oocyst from cat feces or tissue cyst from prey. Fever, respiratory signs
Sheep & Goats Systemic toxoplasmosis & Congenital
toxoplasmosis, ingest oocyst from cat feces Systemic – CNS signs (circling, etc.) Congenital – abortion Vaccine available - Toxovac S48
Toxoplasma
Non-felid paratenic hosts
Cattle Congenital toxoplasmosis (abortion, but
very rare), ingest oocyst from cat feces. Horse
Systemic toxoplasmosis, low pathology, ingest oocyst from cat feces
Toxoplasma
Non-felid paratenic hosts
Swine Systemic toxoplasmosis, ingest oocyst
from cat feces or tissue cyst from prey. Fever, respiratory signs Highly prevalent in free-range pigs Important source of infection for humans
Toxoplasma
Non-felid paratenic hosts
Poultry Systemic toxoplasmosis, ingest oocyst from cat
feces. Prevalent in free-range and back-yard chickens Important source of infection for humans
Rodents Systemic toxoplasmosis, ingest oocyst from cat
feces or tissue cyst from prey. Decreased fear of cats Major source of infection for cats & pigs.
Toxoplasma
ZoonosisSystemic Toxoplasmosis
Systemic Toxoplasmosis Concern for the immunocompromised Transmission
Ingestion of oocysts from cat feces, unwashed vegetables, or unclean hands
Ingestion of tissue cyst from undercooked meat (mainly mutton, goat, free-range pork, free-range chicken)
Toxoplasma
Immunocompetent Person 1st exposure
“flu-like” illness that may last for weeks Fever, myalgia, sore throat,
lymphadenopathy
Future exposures immune-protected, no pathology.
Toxoplasma
ZoonosisSystemic Toxoplasmosis
Immuno-deficient Adult Elderly & those w/ Immunosuppressive DZs
Severe disease (Respiratory, CNS, etc.) If 1st exposure is prior to immune-suppression, then
recrudescence may cause severe DZ If 1st or future exposures are after immune-suppression, then
may cause severe acute DZ
Toxoplasma
ZoonosisSystemic Toxoplasmosis
https://www.memorangapp.com/flashcards/125291/Bro+Path%3A+Neurology+%28B%29+-+Part+1/
http://emedicine.medscape.com/article/229969-overview#showall
Transmission Infection of Mother
Ingestion of oocysts from cat feces, unwashed vegetables, or unclean hands
Ingestion of tissue cyst from undercooked meat (mainly mutton, goat, free-range pork, free-range chicken)
Infection of Fetus Transplacental Transmission
Toxoplasma
ZoonosisCongenital Toxoplasmosis
Fetal Toxoplasmosis Severe DZ
congenital malformation mental retardation death
Toxoplasma
ZoonosisCongenital Toxoplasmosis
Pregnancy, Infection & Immunity If mother’s 1st exposure occurs during pregnancy.
Transplacental transmission is less common early in pregnancy. But more severe defects if transplacental transmission does
occur early.
If mother’s 1st exposure is prior to pregnancy, then mother’s immune system controls toxoplasmosis, unless mother is immune-deficient. Mother can get antibody tested.
Toxoplasma
ZoonosisCongenital Toxoplasmosis
Toxoplasmosis & Pregnancy Advice Get antibody tested Mother & Cat
Sero-positive then no worries for / from either. Avoid cat feces, have someone else clean litter box
daily (sporulation in 1-3 days) Avoid uncooked meat, unclean hands, unclean
vegetables, unclean knives and cutting boards. Casual contact with cats is very low risk.
Indoor cats less risky than outdoor cats. Old outdoor cats less risky than young outdoor cats.
Cats usually only shed oocysts once in their life
Toxoplasma
ZoonosisCongenital Toxoplasmosis
In-Class Discussion
A pregnant client wants to get rid of their cat due to concerns about Toxoplasmosis.
How would you educate your client?
Toxoplasma