Pet ownership, distemper antibodies and multiple sclerosis.

The incidence of cat or dog ownership was similar in 64 multiple sclerosis (MS) patients in south-east England and age- and sex-matched controls. 86% of both groups had owned a cat or dog before the date of onset of MS in the index case so that it would be difficult to detect an association between pet ownership and MS. The titres of neutralising antibody to canine distemper virus were higher in the MS patients (mean 48 +/- 68) than the controls (32 +/- 35), a significant difference (P < 0.05). This difference is not necessarily explained by a cross-reaction with measles antibody of which the titre was much higher in MS (610 +/- 560) than in the controls (320 +/- 330, P < 0.001).