Clinical Signs Diagnosis and Treatment Toxoplasmosis

 Clinical Signs Diagnosis and Treatment Toxoplasmosis


Toxoplasmosis:


Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid (cat) family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself recently been infected, and by transmission from mother to fetus. Cats are the primary source of infection to human hosts, although contact with raw meat, especially pork, is a more significant source of human infections in some countries. Fecal contamination of hands is a significant risk factor.


•          Caused by protozoan – Toxoplasma gondii
•          Domestic cat is the definitive host with infections via:
•          Ingestion of cysts (meats, garden products)
•          Contact with oocysts in feces
•          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 infxn in 3rd trimester
Fetal death higher with infxn in 1st trimester

Clinical Manifestations



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

Diagnosis:



•          Maternal IgG testing indicates past infection (but when…?)
•          Can be isolated in culture from placenta, umbilical cord, infant serum
•          PCR testing on WBC, CSF, placenta
•          Not standardized
•          Newborn serologies with IgM/IgA

Toxo Secreening:

•          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 for Toxoplasmosis :



•          Treatment for pregnant mothers diagnosed with acute toxo
•          Spiramycin daily
•          Macrolide antibiotic
•          Small studies have shown this reduces likelihood of congenital transmission (up to 50%)
•          If infant diagnosed prenatally, treat mom
•          Spiramycin, pyrimethamine (anti-malarial, dihydrofolate reductase inhib), and sulfadiazine (sulfa antibiotic)
•          Leucovorin rescue with pyrimethamine
•          Symptomatic infants
•          Pyrimethamine (with leucovorin rescue) and sulfadiazine
•          Treatment for 12 months total
•          Asymptomatic infants
•          Course of same medications
Improved neurologic and developmental outcomes demonstrated (compared to untreated pts or those treated for only one month.