CNS Infections- T. gondii

Question 1

Toxoplasma gondii/Toxoplasmosis is

Answer 1

a tissue protozoan (eucaryote) and an obligate intracellular parasite

Question 2

Can infect what type of cells?

Answer 2

any nucleated host cell

spreads to all organs and tissues

Question 3

Latent pseudocyst found primarily in __________ T. gondii cannot form a true cyst as per T. solium (a helminth) cysticerci. The pseudocyst is formed by _________. Clinical symptoms occur during reactivation due to specific immunosuppression.

Answer 3

the brain and muscle

the host immune system in response to the trophozoite

Question 4

Hosts

Answer 4

definitive host- cat

intermediate- humans

Question 5

Transmission

Answer 5

• Ingestion of tissue pseudocysts in undercooked or uncooked meat (esp. pork or lamb)
• Inhalation or ingestion of mature oocyst (passed in feces of cat)

Question 6

Causes what?

Answer 6

Multifocal mass lesions

Question 7

Sites where lesions are most commonly found?

Answer 7

CNS most common, eye, lung, muscle

Question 8

If the host CMI response weakens/decreases T-cells, may cause reactivation of latent infection, pseudocysts breakdown releasing trophozoites and damage host. Common T cell suppressive disorders pts have are:

Answer 8

AIDS, transplant pt., Hodgkin’s disease

Question 9

Reactivation diseases

Answer 9

Diffuse encephalitis, Multifocal mass lesion or generalized seizures, Disease in eye and/or lung

Question 10

S/S

Answer 10

1. altered mental status,
   2. weakness,
   3. cranial nerve abnormalities,
   4. neuropsychiatric disorders,
   5. focal or generalized seizures

Question 11

If pt has this their CD4+ count will be

Answer 11

CD4+ count

Question 12

CT scan will show

Answer 12

ring enhancing lesions

Question 13

MRI will show

Answer 13

1. Contrast enhancing lesions after administration of gadolinium
2. Toxoplasma encephalitis:
   - multiple bilateral cerebral lesions in the juxtacortical and basal ganglia areas.
   - ganglia and are hypodense with ring-enhancement

Question 14

CT (SPECT) scan will be

Answer 14

Negative thallium-201 single-photon emission CT (SPECT) scan

Question 15

IgM? Present or no?

Answer 15

NO IgM

toxoplasmosis IgG seropositive

Question 16

Treatment

Answer 16

• 2→4 months of a combination of sulfonamides (sulfadiazine) or clindamycin plus pyrimethamine.
• only treats trophozoites, (i.e., active disease) not latent infection of pseudocysts, so it not a cure, hence in immunosuppressed patient, prophylaxis after disease is lifelong

Question 17

Prevention

Answer 17

Pregnant women, Advanced HIV patients, SOT patients on immunosuppressive therapy, etc. should be instructed to avoid cats, cat feces and Cook pork well, not pink