Toxoplasmosis

Question 1

Infective stage of toxoplasma?

Answer 1

Bradyzoites

Question 2

Organism for toxo?

Answer 2

Toxoplasmosis Gondii

Question 3

Diagnostic stage of toxo?

Answer 3

issue cysts with bradyzoites (biopsy), tachyzoites.

Question 4

Mode of transmission?

Answer 4

Classic: immature oocysts - from cat faeces (classic)
mature oocysts - contaminated food

But more commonly pig meat containing bradyzoites (undercooked)

Question 5

Following ingestion of bradyzoites, what stage of toxo spreads to tissues?

Answer 5

Tachyzoites

Question 6

Organs affected by toxo?

Answer 6

Brain, eyes, muscles, fetes

Question 7

What is this?

Answer 7

Crescent shaped tachyzoite of toxoplasmosis
Pointed anterior end
Prominent nucleus

Question 8

Structure/stage of life cycle in toxo in tissues?

Answer 8

Bradyzoite

Question 9

What is this?

Answer 9

Bradyzoite

Question 10

Definitive host for toxoplasmosis? Intermediate hosts?

Answer 10

Cats (D)
Humans (I)

Question 11

High prevalence areas of toxo?

Answer 11

France - eating raw or undercooked meat
Central America has been related to the frequency of stray cats

Question 12

If immunocompetent person gets toxo, symptoms?

Answer 12

10% to 20% of patients with acute infection may develop cervical lymphadenopathy and/or a flu-like illness

Mostly asymptomatic!

Rare: ocular damage, visual disturbances

Question 13

Diagnosis of toxo?

Answer 13

Isolation of parasites from blood or other body fluids, by intraperitoneal inoculation into mice or tissue culture

ELISA for IgG and IgM antibodies most common

Question 14

What should you do if you get a positive IgM antibody for toxo (IgG negative)

Answer 14

Repeat in 2 weeks - could be fast positive or acute infection
IgG should be positive 2 weeks later if acute infection.
IgM can sometimes be present for up to 2 yrs

Question 15

Rx of Toxo?

Answer 15

Pyrimethamine plus sulfadiazine or clindamycin
Alternative: Co-trimoxazole

Question 16

Positive IgG toxo but negative IgM, meaning?

Answer 16

Infected with Toxoplasma for six months or more.

Question 17

2 stages of life cycle that are infective?

Answer 17

Cysts with bradyzoites from raw meat
Oocysts with sporozoites from cat faeces

Question 18

Of those that get infected, how many have symptoms of toxoplasmosis?

Answer 18

10%

Question 19

Symptoms of reactivation of toxo vs acute infection

Answer 19

Chorioretinitis vs
Acute: mononucleosis like syndrome with lymphadenopathy

Rarely presents with myocarditis, pericarditis, hepatitis

Question 20

How does toxo present in pregnancy? Risk to fetus?

Answer 20

Recurrent abortions
Congenital CNS and eye disease

Question 21

How does toxo in eye present?

Answer 21

CR: Painless visual loss
Can also see a scar

Question 22

Toxo in CNS in immunocompromised patients?

Answer 22

Diffuse meningoencephalitis and isolated cerebral lesions - single, ring enhancement

Question 23

Rx of CNS Toxo?

Answer 23

Dexamethasone plus Pyrimethamine plus sulfadiazine PLUS FOLINIC ACID (NOT FOLIC)

Question 24

Symptoms of toxo in HIV?

Answer 24

Focal signs, headache, seizures, confusion

Question 25

SEs of pyrimethamine and sulfidiazine, how to prevent?

Answer 25

Anaemia, leukopenia, thrombocytopenia
FOLINIC ACID

Question 26

First 20 weeks of pregnancy with acute toxo Rx?

Answer 26

Spiramycin then switch

Question 27

Rx of a neonate with congenital toxo?

Answer 27

Pyrimethamine + Sulfadiazine + folinic acid

Question 28

Primary prophylaxis vs secondary prophylaxis of toxo in immunocompromised host?

Answer 28

Primary: co-trimoxazole
Secondary (had toxo Rx): continue pyrimethamine and sulfadiazine