The relationship between ocular toxoplasmosis and levels of specific toxoplasma antibodies

The relationship between ocular toxoplasmosis and levels of toxoplasma specific antibodies was examined in 195 patients. Using clinical information collected by questionnaires, patients were divided into: 97 with ocular toxoplasmosis (group 1) and 98 with ocular lesions not due to toxoplasma (group 2). The geometric mean of dye test titres (±<e5>S.D.</e5> natural log titre) in group 1 was 53·2 (±0·95) compared with 24·6 (±1·11) in group 2 (<e1>P</e1>&lt;0·001). Young females tended to have more active lesions compared with young males (<e1>P</e1>&lt;0·05). There was an age-dependent difference in dye test titres between the groups (<e1>P</e1>&lt;0·001). Group 1 showed a decline in titre with age compared with an increase in group 2. Ocular toxoplasmosis was diagnosed most frequently among 21–30 year olds. More group 1 patients had dye test titres 65 iu/ml than group 2 (<e1>P</e1>&lt;0·05). Dye test titres 65 iu/ml support a diagnosis of ocular toxoplasmosis whereas lower titres suggest other causes for eye lesions.