Toxoplasma gondii Flashcards
Toxoplasma gondii is the main cause of?
Abortion in sheep
What are the end results of asexual and sexual reproduction?
Asexual = multiplication of parasite numbers
Sexual reproduction = recombination of genetic material
What are some characteristics of an apical complex?
- involved in host cell invasion
- single celled
- distinguishable by the conoid at the end of the parasite
- contains: dense cell granules, microneme, rhoptry
Name the 3 stages of growth of the toxoplasma gondii parasite
- Tachyzoite
- Bradyzoite
- Oocyst
Describe a tachyzoite
- Intracellular
- Rapidly dividing
- Crescent shaped - 2-6um
Describe a bradyziote
- Within a bradyzoite cyst
- Neural or muscle tissue
- Slow growing
- Persistant
Describe an oocyst
- Unsporulated oocyst passed in faeces
- 12um
- Sporulated oocyst => two sporocysts => 4 sporozoites
What is the definitive host of Toxoplasma gondii?
Cat
How do cats become infected with Toxoplasma?
Ingesting bradyzoite cysts in the tissues of prey
Describe the life cycle of Toxoplasma inside the definitive host
- sexual cycle occurs in the small intestine
- unsporulated oocysts shed in faeces
How does infection of the intermediate host with toxoplasma occur?
- Oocysts sporulate to two sporocysts and then to four sporozoites
- these contaminate the environment before being ingested by any warm blooded mammal
Describe the life cycle of Toxoplasma inside the intermediate host
- sporozoite’s released and travel across the gut wall
- develop into tachyzoites which replicate rapidly
- differentiate into bradyzoites which form cysts
Describe toxoplasmosis in sheep
- Transmission by ingestion of infective sporulated oocysts
- Oocysts from cats that contaminate the pasture
- No direct sheep-sheep transmission
How many oocysts can be out put from a cat?
more than 10,000
How many oocysts does it take to cause abortion in a sheep?
1000