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Published on: June 8, 2017
A systematic review of neonatal toxoplasmosis exposure and sensorineural hearing loss
Erik D Brown1, Justin K Chau, Shahnaz Atashband
1Division of Pediatric Otolaryngology, BC Children's Hospital, Department of Surgery, University of British Columbia, Vancouver, BC, Canada.
Insights
Congenital toxoplasmosis infection can cause sensorineural hearing loss (SNHL). Early and compliant antiparasitic treatment significantly reduces SNHL prevalence, with 0% in optimally treated infants.
Area of Science:
- Ophthalmology
- Pediatrics
- Infectious Diseases
Background:
- Congenital toxoplasmosis is a risk factor for sensorineural hearing loss (SNHL) in infants.
- Audiologic monitoring is recommended for children with congenital toxoplasmosis.
Purpose of the Study:
- Determine the prevalence of SNHL in congenital toxoplasmosis.
- Develop evidence-based guidelines for audiologic monitoring.
Main Methods:
- Systematic literature search (Medline, EMBASE, Cochrane).
- Inclusion of longitudinal studies with confirmed congenital toxoplasmosis and serial audiometry.
- Independent data extraction and descriptive statistical analysis.
Main Results:
- Prevalence of toxoplasmosis-associated hearing loss ranged from 0% to 26% across studies.
- SNHL prevalence was 28% with no/limited treatment, 12% with delayed/non-compliant treatment, and 0% with early, compliant 12-month treatment.
- No delayed-onset or progressive SNHL cases were reported in the limited longitudinal studies.
Conclusions:
- Optimal treatment (12-month antiparasitic therapy initiated before 2.5 months with confirmed compliance) is associated with 0% SNHL.
- Recommend audiometric re-evaluation at 24-30 months for optimally treated infants.
- Annual monitoring is advised for infants with incomplete, delayed, or non-compliant treatment.
Introduction:
The Joint Committee on Infant Hearing 2007 Position Statement includes in utero toxoplasmosis infection as a risk indicator for delayed-onset or progressive sensorineural hearing loss. It is recommended that children with congenital toxoplasmosis infection undergo audiologic monitoring to identify congenital and delayed-onset sensorineural hearing loss.
Objective:
To determine the prevalence of sensorineural hearing loss and to develop evidence-based guidelines for audiologic monitoring of children born with congenital toxoplasmosis infection.
Data Sources:
Systematic search of Medline, EMBASE and Cochrane databases and manual search of references.
Study Selection:
Longitudinal studies reporting an inception cohort identified at birth, with serologic confirmation of toxoplasmosis infection, and long-term serial audiometric evaluation.
Data Extraction:
Independent extraction of patient and audiometric data.
Data Synthesis:
Descriptive statistics.
Conclusion:
The five studies meeting our inclusion criteria report a prevalence of toxoplasmosis-associated hearing loss from 0% to 26%. Improved treatment regimens for toxoplasmosis may account for this range. Three treatment groups were identified and a subgroup analysis of the compiled data was performed. In children receiving limited or no treatment, the prevalence of toxoplasmosis-associated SNHL was found to be 28%. In children prescribed 12 months of antiparasitic treatment but in whom treatment was not confirmed to have started prior to 2.5 months of age and in whom compliance was not ensured, the prevalence of SNHL was 12%. In children treated with 12 months of antiparasitical therapy initiated prior to 2.5 months of age with serologically-confirmed compliance, the prevalence of SNHL was 0%. Only two longitudinal studies were identified and neither reported any cases of delayed-onset or progressive toxoplasmosis-associated SNHL. Children who have received a 12-month course of antiparasitical therapy initiated prior to 2.5 months with serologically-confirmed compliance should have repeat audiometric evaluation at 24-30 months of age. Children with congenital toxoplasmosis that had no treatment, partial treatment, delayed onset of treatment, or compliance issues should undergo annual audiologic monitoring until able to reliably self-report hearing loss.
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