Indirect life cycles Flashcards
What is the DH of toxoplasma gondii?
Cat
How is the DH infected with toxoplasma gondii?
Ingesting quiescent bradyzoites, which are found within tissue cysts. These penetrate the epithelial cells in the small intestine.
Ingesting rapidly multiplying tachyzoites in recently infected IH.
How long after infection does the DH shed toxoplasma gondii eggs?
3 weeks after infection
Upon ingestion by the IH/AH, how long does it take for the toxoplasma gondii oocyst to sporulate?
1-5 days
What is the route of transmission to IH/AH by toxoplasma gondii?
Carnivorism/omnivorism.
Transplacentally - humans, sheep and goats.
What does the presence of tachyzoites indicate?
Acute tissue phase of infection
How long does it take for tachyzoites to be generated in vitro?
6-8 hours
What is endodyogeny?
2 progeny forms within the parent parasite
What is the lytic cycle of a tachyzoite?
Tachyzoite penetrates the host cell.
Endodyogeny.
Host cell ruptures when it can no longer support the growth rate of tachyzoites.
Where are bradyzoites found?
Within tissue cysts
What are the locations of chronic toxoplasmosis?
Muscle and brain tissue
How long does it take for a tissue cyst to form after infection by toxoplasma gondii?
7-10 days
What are the properties of a cyst wall?
Composed of host and parasite material.
Resistant to digestion by gastric juices.
Protected from the host’s immune system.
Why are immunocompromised patients at risk by toxoplasma gondii?
Usually there is a low rate of spontaneous reactivation of bradyzoites to tachyzoites. Normally, this is prevented by the immune system.
What are the signs of a toxoplasma gondii infection in early gestation of sheep/goats?
Abortion - so appear to be a barren ewe.
What are the signs of a toxoplasma gondii infection in mid-gestation of sheep/goats?
Abortion
Lesions of cotyledons in the placenta
Mummification of foetus
Dead foetus
What are the signs of a toxoplasma gondii infection in late gestation of sheep/goats?
Still born
Weak lambs
How are humans infected with toxoplasma gondii?
Raw meat
Unpasteurised products
Ingestion of oocysts
What are the signs of an acute infection in humans of toxoplasma gondii?
Swollen lymph nodes
Muscle aches & pains
What are the signs of an severe infection in humans of toxoplasma gondii?
Damage to the brain, eyes and other organs.
What are the signs of a congenital infection in humans of toxoplasma gondii?
Serious eyes or brain damage
What is the DH of neospora caninum?
Canine
What is the IH of neospora caninum?
Cattle
What are the signs of an infection of neospora caninum in dogs?
Myositis - inflammation of muscles
Paralysis - encephalomyelitis
What are the signs of infection of neospora caninum in cattle?
Abortion
What is the exogenous pathway for infection by neospora caninum?
Ingestion of sporulated oocysts.
This affects naive individuals or by the DH.
What is the endogenous pathway for infection by neospora caninum?
Infections resulting from reactivation of bradyzoites during pregnancy.
Primary route of infection in cattle.
Does not involve DH.
Maintenance of infection in endemic herds.
What is the DH of sarcocystis?
Carnivores
What is the IH of sarcocystis?
Herbivores
What is the sarcocystis species of cattle to dogs?
Sarcocystis bovicanis/cruzi
What is the sarcocystis species of sheep to dogs?
Sarcocystis ovicanis/tenella
What is the sarcocystis species of cattle to humans?
Sarcocystis bovihominis
