Newborns in Brazil are more susceptible to toxoplasmosis than those in Europe, according to a recent study. Researchers based in Austria, Brazil, Denmark, France, Italy, Poland, Sweden, and the United Kingdom studied the disease's ocular effects in children from birth to four years of age. Details are published August 13th in the open-access journal PLoS Neglected Tropical Diseases.

Toxoplasmosis, caused by Toxoplasma gondii, is the most common parasitic disease found in humans around the world. Infection can cause inflammatory lesions at the back of the eye that sometimes affect vision. Previous studies have suggested more severe complications when people acquire the disease in Brazil than in Europe or North America but have not compared patients directly.

For this study, headed by Ruth Gilbert at the Institute of Child Health, University College London, children with congenital toxoplasmosis were identified by routine screening of their mothers during pregnancy or of the newborn soon after birth. Gilbert's group found that Brazilian children had a five times higher risk than European children for developing eye lesions by four years old. Furthermore, lesions in the retina occurred more frequently and were larger in the Brazilian children, and vision was predicted to be compromised in 87% of the Brazilian children, compared to only 29% in the European children.

The authors believe the more severe clinical symptoms in Brazil are due to infection with more virulent genotypes of the parasite that are predominant in Brazil but rarely found in Europe.