DM2 Pt3-2 Toxoplasma gondii

Question 1

What type of organism is Toxoplasma gondii?

Answer 1

Toxoplasma gondii is an obligate intracellular coccidian parasite.

Question 2

Which species are natural hosts for T. gondii?

Answer 2

Domestic cats and other felids are the natural hosts of T. gondii, while non-feline species serve as intermediate hosts.

Question 3

How common is T. gondii infection in cats?

Answer 3

Up to 50% of cats, especially free-roaming ones, have antibodies indicating T. gondii infection.

Question 4

What are the three infectious stages of T. gondii?

Answer 4

The three stages are sporozoites in oocysts, tachyzoites, and bradyzoites in tissue cysts.

Question 5

How are sporozoites in oocysts transmitted?

Answer 5

Sporozoites are shed in a cat’s faeces, and transmission occurs through ingestion of contaminated soil or water.

Question 6

How can tachyzoites be transmitted?

Answer 6

Tachyzoites can be transmitted transplacentally from an infected mother to her foetus, or through milk during lactation.

Question 7

What is the function of bradyzoites in T. gondii infection?

Answer 7

Bradyzoites are a slowly dividing stage within tissue cysts that persist in the host for life and can reactivate under immunosuppression.

Question 8

How do most cats become infected with T. gondii?

Answer 8

Most cats are infected by ingesting prey (such as rodents) containing bradyzoites.

Question 9

When do cats shed oocysts after ingesting infected prey?

Answer 9

Oocysts are shed in the faeces after 3 days and continue to be shed for 10-21 days.

Question 10

What is the enteric-epithelial life cycle of T. gondii in cats?

Answer 10

This life cycle occurs only in cats and is typically completed 3-10 days after ingestion of infected prey containing tissue cysts.

Question 11

What happens during the extraintestinal life cycle of T. gondii in hosts?

Answer 11

Tissue cysts form in the CNS, muscles, and visceral organs and may persist for life, with potential reactivation after immunosuppression.

Question 12

How can T. gondii infection affect kittens born to infected queens?

Answer 12

Kittens can become infected transplacentally or through suckling if the queen is infected during gestation.

Question 13

When do clinical signs of Toxoplasma gondii infection typically appear in cats?

Answer 13

Clinical signs usually appear in immunosuppressed cats when cystic stages reactivate.

Question 14

What organs or systems are commonly affected in cats with toxoplasmosis?

Answer 14

The CNS, muscles, lungs, and eyes are commonly affected in cats with toxoplasmosis.

Question 15

What are common clinical signs of toxoplasmosis in cats?

Answer 15

Neurological signs (e.g., seizures, ataxia), muscle hyperaesthesia, dyspnoea, uveitis, icterus, diarrhoea, fever, depression, anorexia, and weight loss.

Question 16

How does Toxoplasma gondii infection affect transplacentally infected kittens?

Answer 16

Infected kittens often develop severe signs and may die from pulmonary or hepatic disease.

Question 17

How long do cats shed T. gondii oocysts after ingesting tissue cysts?

Answer 17

Cats shed oocysts for 3–10 days after ingesting tissue cysts, and this occurs only once in their lifetime.

Question 18

Why do antibody-positive cats not pose a risk of shedding oocysts?

Answer 18

Antibody-positive cats no longer shed oocysts, as shedding occurs only once, and usually before antibodies have developed.

Question 19

What type of antibodies do infected cats develop?

Answer 19

Infected cats develop IgG, IgA, and in about 80% of cases, IgM antibodies.

Question 20

How is Toxoplasma gondii infection diagnosed in cats?

Answer 20

Oocyst shedding is diagnosed by microscopy of faecal samples, while the disease is confirmed when the organism is found in body fluids or tissues.

Question 21

Why does the presence of T. gondii antibodies not prove clinical toxoplasmosis?

Answer 21

Antibodies are found in both healthy and sick cats, and IgM antibodies can also be detected in healthy cats.

Question 22

What is the treatment of choice for toxoplasmosis in cats?

Answer 22

Clindamycin (10–12 mg/kg orally q12h for 4 weeks) is the treatment of choice for toxoplasmosis.

Question 23

How should systemic toxoplasmosis with uveitis be treated?

Answer 23

Cats should be treated with clindamycin and topical, oral, or parenteral glucocorticoids to prevent secondary glaucoma and lens luxation.

Question 24

How can toxoplasmosis be prevented in cats?

Answer 24

Prevent cats from hunting or eating raw meat, feed them commercially processed food, and keep them out of areas with food-producing animals or feed storage.