toxoplasmosis

Congenital Toxoplasmosis

Anand Gourishankar, MD, and Robert Lapus, MD
University of Texas Medical School, Houston

A 2-month-old boy had been doing well after birth until about 7 or 8 weeks of life. His parents felt that he was not smiling, and was only looking to the right. At 10 weeks of age, they felt that he was not responding to light. Upon further questioning, the family reported that the boy had never demonstrated a social smile or tracking, and that at 6 to 7 weeks of life, he would preferentially look to the right. He had experienced no problems with breastfeeding.

The boy had been born at 38 weeks of gestation via spontaneous vaginal delivery without complications. The mother had received adequate prenatal care, and her prenatal laboratory test results were normal. She had had a fever of 39.4°C at week 4 to 5 of gestation and a stomach virus with a fever of 38.9°C at 32 weeks of pregnancy. The mother’s family history was remarkable for maternal uncle who had been born with “visual and brain impairment,” other family members with boils from methicillin-resistant Staphylococcus aureus infection, and a paternal grandmother with hypothyroidism.

On physical examination, the infant appeared to be thriving. His weight was 5.22 kg (27th percentile), height was 63 cm (90th percentile), and head circumference was 39 cm (15th percentile). Fundoscopic examination showed what appeared to be at least 3 “scars” on the child’s left retina, with an absent red-orange reflex. The right-sided eye gaze was noticed intermittently, but the rest of the physical examination findings were unremarkable.

An ophthalmologist was consulted based on concern for a possible TORCH infection (toxoplasmosis, other [eg, syphilis, varicella zoster virus, parvovirus B19], rubella, cytomegalovirus, and herpes).

Further history revealed that the family had 2 cats, and that while the patient’s mother had not changed the litter since her first pregnancy, she had helped her husband clean the litter box but says she did not touch it. She also had traveled from her home near Houston, Texas, to New Orleans, Louisiana, and to Austin and Dallas, Texas. She had stayed with friends who have cats. She denied having other pets; swimming in lakes, rivers, or ponds; and eating uncooked, unpasteurized, or undercooked food. She denied sick contacts and tick or mosquito bites.

Urine culture results were negative for cytomegalovirus. Polymerase chain reaction test results of the infant’s cerebrospinal fluid were negative for Toxoplasma gondii DNA. Results of serologic testing for toxoplasma-specific IgG antibodies were positive, with a 1:8,000 titer; immunosorbent agglutination assay results were positive for Toxoplasma IgM; and enzyme-linked immunosorbent assay (ELISA) results were positive for Toxoplasma at 2.1 (in infants younger than 6 months of age, ≥ 1 is positive). The latter 2 serologic tests are highly sensitive for congenital toxoplasmosis.

The mother’s serologic test results were positive for Toxoplasma IgG at 1:8,000, and ELISA results were positive for Toxoplasma IgM at 5.1.

Results of electroencephalography showed slowing of the right hemisphere compared with the left, with bilateral epileptiform activities; hence, levetiracetam was started. Magnetic resonance imaging of the infant’s brain showed mild lateral ventriculomegaly and a few areas of periependymal enhancement (A), along with encephalomalacia and calcifications (B).

Figure A. Brain MRI of a 2-month-old boy showed mild lateral ventriculomegaly and a few areas of periependymal enhancement (arrow).

Figure B. Brain MRI also showed encephalomalacia and calcifications (arrow).

The infant was treated with sulfadiazine, leucovorin, and pyrimethamine.

Cats are the primary hosts for T gondii, and humans accidentally become infected with the protozoan by handling cat feces.1 The prevalence of congenital infection ranges from 0.1 to 0.3 cases per 1,000 live births, and vertical transmission is higher with delayed seroconversion in a mother.2

Ocular manifestations are the most common findings and the usual presenting symptom of toxoplasmosis. Infants with congenital infection are asymptomatic at birth in 70% to 90% of cases. Signs of congenital toxoplasmosis at birth can include a maculopapular rash, generalized lymphadenopathy, hepatomegaly, splenomegaly, jaundice, pneumonitis, diarrhea, hypothermia, petechiae, and thrombocytopenia. As a consequence of intrauterine infection, meningoencephalitis, CSF abnormalities,3 hydrocephalus, microcephaly, chorioretinitis, seizures, and deafness can develop. The classical triad of cerebral calcifications, chorioretinitis, and hydrocephalus is rare but highly suggestive of congenital toxoplasmosis.

The forms of T gondii found in the United States usually are less aggressive than those found in other parts of the world. Screening for toxoplasmosis is not routine in pregnancy in the United States, unlike in other parts of the world.4 A partially treated or untreated infant is at higher risk for sensorineural hearing loss.5

References

1. Kaye A. Toxoplasmosis: diagnosis, treatment, and prevention in congenitally exposed infants. J Pediatr Health Care. 2011;25(6):355-364.

2. Kieffer F, Wallon M. Congenital toxoplasmosis. Handb Clin Neurol. 2013; 112:1099-1101.

3. de Jong EP, Vossen ACTM, Walther FJ, Lopriore E. How to use… neonatal TORCH testing. Arch Dis Child Educ Pract Ed. 2013;98(3):93-98.

4. Montoya JG, Remington JS. Management of Toxoplasma gondii infection during pregnancy. Clin Infect Dis. 2008;47(4):554-566.

5. Brown ED, Chau JK, Atashband S, Westerberg BD, Kozak FK. A systematic review of neonatal toxoplasmosis exposure and sensorineural hearing loss. Int J Pediatr Otorhinolaryngol. 2009;73(5):707-711.