Sensorineural hearing loss due to Toxoplasma gondii in children: a case–control study

Abstract

Sensorineural hearing loss (SNHL) can follow congenital toxoplasmosis. Treatment in the first year of life is associated with diminished occurrence of this sequel. In various parts of Iran, the prevalence of antibodies to Toxoplasma gondii ranges from 24% to 57.7%. We evaluate the possible role of Toxoplasma gondii infection on the occurrence of SNHL in children. This case-control study was performed in a tertiary care center in Tehran between 2002 and 2003. This study was carried out based on diagnostic parameters of the American Academy of Otolaryngology criteria for SNHL and a healthy control group. We compared the specific Toxoplasma gondii antibodies (IgM & IgG) measured by ELISA in 95 blood samples of infants with SNHL and 63 healthy matched infants. Acute (IgM) and previous (IgG) immunity to Toxoplasma gondii was found in 12 and 21.2% of SNHL children, respectively. Most cases with previous infections (IgG positive) were children aged less than 1 year old (i.e. maternal immunity), but acute infection (IgM positive) was higher in 3-5 year old age group. Acute infection (IgM) was significantly more frequent in the SNHL group, and previous immunity was higher in the controls (CI 95%, P-value = 0.01; 0.01). With respect to seropositive children, as we were unable to differentiate congenital from acquired cases, we recommend prevention of congenital toxoplasmosis by treatment of Toxoplasma infection in pregnant women and treatment of acquired Toxoplasma gondii infection after birth to minimise the risk of SNHL in children.