Toxoplasma gondii
By: Cory Polacek & Nicole Bertram
Background
Obligate intracellular parasite
Found in many kinds of tissue including muscle and intestinal epithelium
One of most common human parasites in the world First discovered in the gundi (N.African rodent) in 1908
Hosts
Geographic Range
World wide Less frequent in extreme temperatures and higher altitudes
Definitive hosts: members of cat family Intermediate host: any warm blooded mammal or bird
Life Cycle
Two Phases
Sexual Asexual
Life Cycle-Sexual
Cat is infected by ingesting oocysts or eating an infected intermediate Bradyzoites or sporozoites penetrate cells of small intestine Parasite undergoes asexual as well as sexual reproduction (sexual reproduction only occurs in cats Oocysts are produced from sexual reproduction Cat passes oocysts in fecal matter Oocysts become infective after about 24 hours (sporulate) Oocysts can them be ingested by an intermediate host…
Life Cycle-Asexual
Intermediate host ingests bradyzoites or oocysts and infect macrophages in the mucosa of the small intestine Within the macrophage tachyzoites develop Tachyzoites rapidly asexually reproduce and are distributed throughout the host body After several weeks parasite divides slower and produces zoitocysts filled with bradyzoites (inactive stage that forms after the immune response is triggered) The infected intermediate can then be ingested by the definitive host or another intermediate.
Tachyzoites
(asexually reproducing)
Oocyst
(sexual reproducing)
Sources of Infection
Accidental ingestion of infected cat fecal matter Contaminated food/utensils from raw meat Contaminated drinking water Receiving infected organ transplant or blood transfusion (rare)
Pathogenesis/Clinical Signs
Most cases are asymptomatic Flu like symptoms, swollen lymph glands and muscle aches and pains Some suffer from hepatitis, pneumonia, blindness and severe neurological disorders (acute infections)
Especially true for individuals with compromised immune systems (AIDS)
Public Health Concerns
Risk to pregnant mothers and babies
If mother is infected prior to pregnancy there is virtually no risk of fetal transmission If mother becomes infected during pregnancy fetus is at risk (congenital toxoplasmosis) Fetal infection could result in still-birth or spontaneous abortion 70% of infants born with congenital toxoplasmosis are asymptomatic, but 8% show severe CNS impairment
Diagnosis/Treatment
Diagnosis in humans is based on laboratory tests
Biopsy ELISA
Pyrimethamine and sulfonamides are given together
Control Methods
Freeze meat at -14° C if you like to eat it undercooked. Reduce the number of stray cats. Clean the litter box every day. Keep sandboxes covered.
Sources
http://www.emedicine.com/emerg/topic601.html http://www.biosci.ohio-state.edu/~parasite/toxoplasma.html http://www.cdc.gov/ncidod/dpd/parasites/toxoplasmosis/factsht_to xoplasmosis.htm http://cvm.msu.edu/courses/mic569/docs/parasite/TOXO.HTML http://en.wikipedia.org/wiki.Toxoplasma_gondi Foundations of Parasitology
Special Thanks
We would like to thank baby Gary for posing for our presentation We would like to thank Gary, Kenya, Sushi and Mika for possibly infecting us with T.gondii And thanks to all the cats in the world for possibly altering our personalities to become “sex kittens” !!!