Provision of a panel of anti-toxoplasma-negative blood donors.

Toxoplasma gondii has been reported to cause complications only in immunosuppressed patients receiving leucocyte transfusion, when severe acute toxoplasmosis has been reported with associated mortality. At the North London Blood Transfusion Centre (NLBTC) we have screened 392 plasmapheresis donors (using toxoreagent latex agglutination test manufactured by Eiken) to provide a panel of blood donors negative for antibody to toxoplasma for seronegative recipients. A toxoplasma-negative panel of donors would only be required for those rare instances when granulocyte concentrates are indicated for transfusion of seronegative recipients. The toxoreagent test classified the 392 blood donors as 36% positive, 23% weakly reactive and 41% negative; these negative sera were retested with toxoreagent and 17% of them reacted weakly but none were positive. The toxoreagent 'weakly-reactive' sera (all of which were Sabin-Feldman dye test negative) can probably best be accounted for by the exacting screening conditions under which we operated to ensure seronegativity in our special donor panel. 40% of the antibody-positive donors were female and 34% male. Seropositivity increased with age.