Toxoplasmosis Clinical Signs Diagnosis and Treatment

Toxoplasmosis:

•          Caused by protozoan – Toxoplasma gondii

•          The domestic cat is the definitive host with infections via:

•          Ingestion of cysts (meats, garden products)

•          Contact with oocysts in faeces

•          Much higher prevalence of infection in European countries (ie France, Greece)

•          Acute infection usually asymptomatic

•          1/3 risk of fetal infection with primary maternal infection in pregnancy

•          Infection rate higher with infection in the 3^rd trimester

Fetal death higher with infection in the 1^st trimester

Clinical Manifestations

•          Most (70-90%) are asymptomatic at birth

•          The classic triad of symptoms:

•          Chorioretinitis

•          Hydrocephalus

•          Intracranial calcifications

•          Other symptoms include fever, rash, HSM, microcephaly, seizures, jaundice, thrombocytopenia, lymphadenopathy

•          Initially asymptomatic infants are still at high risk of developing abnormalities, especially chorioretinitis 

Chorioretinitis

Diagnosis:

•          Maternal IgG testing indicates past infection (but when…?)

•          Can be isolated in culture from the placenta, umbilical cord, infant serum

•          PCR testing on WBC, CSF, placenta

•          Not standardized

•          Newborn serologies with IgM/IgA

Toxo Screening:

•          Prenatal testing with varied sensitivity not useful for screening

•          Neonatal screening with IgM testing implemented in some areas

•          Identifies infected asymptomatic infants who may benefit from therapy

Prevention and Treatment:

•          Treatment for pregnant mothers diagnosed with acute toxoplasmosis.

•          Spiramycin daily

•          Macrolide antibiotic

•          Small studies have shown this reduces the likelihood of congenital transmission (up to 50%)

•          If infant diagnosed prenatally, treat mom

•          Spiramycin, pyrimethamine (anti-malarial, dihydrofolate reductase inhibitor), and sulfadiazine (sulfa antibiotic)

•          Leucovorin rescue with pyrimethamine

•          Symptomatic infants

•          Pyrimethamine (with leucovorin rescue) and sulfadiazine

•          Treatment for 12 months of total

Improved neurologic and developmental outcomes demonstrated (compared to untreated pts or those treated for only one month