Seroprevalence and risk factors for toxoplasmosis among antenatal women in London: a re-examination of risk in an ethnically diverse population

BACKGROUND Primary infection with Toxoplasma gondii in pregnancy can result in miscarriage, hydrocephalus, cerebral calcification and chorioretinitis in the newborn. The objective of our study was to evaluate seroprevalence of and analyse risk factors for toxoplasmosis in antenatal women from 2006 to 2008 in an ethnically diverse population of Central London to re-examine the need for a screening policy. METHODS We performed serum IgG estimations to T. gondii using a commercial kit, and analysed risk factors for acquisition using a questionnaire. RESULTS Seroprevalence for T. gondii was 17.32% in 2610 samples tested. In all, 67.7% were of UK origin (seroprevalence: 11.9%) and were significantly non-immune to T. gondii (OR: 0.38, 95% CI: 0.31-0.47; P < 0.0001). Risk factors for seroprevalence included African/Afro-Caribbean (OR: 2.67, 95% CI: 1.83-3.88; P < 0.001; seroprevalence: 31.5%), Middle eastern (OR: 3.12, 95% CI: 1.62-5.99; P ≤ 0.001; seroprevalence: 34.8%) and mixed (OR: 1.75, 95% CI: 1.16-2.63; P = 0.007; seroprevalence: 23.3%) ethnic groups; eating undercooked meat (OR: 1.64, 95% CI: 1.29-2.08; P ≤ 0.001; seroprevalence: 20.2%) and drinking unpasteurised milk (OR: 1.38, 95% CI: 1.01-1.88; P = 0.05; seroprevalence: 23.1%). There was no association with pet cats or eating unpasteurised cheeses and antibody responses. CONCLUSION Low national prevalence of toxoplasma seroconversion and congenital disease would likely not justify screening in the UK. Individual risk assessment is recommended in ethnically diverse urban areas where populations with relatively high seroprevalence and parasite-associated risk factors exist together with an indigenous population with low prevalence. One universal screening policy based on the indigenous prevalence and risk factors may not be suitable for all.