[1] PALO ALTO MED RES FDN, RES INST, DEPT IMMUNOL & INFECT DIS, PALO ALTO, CA 94301 USA
[2] STANFORD UNIV, MED CTR, SCH MED, DEPT MED, DIV INFECT DIS, STANFORD, CA 94305 USA
[3] INST PUERICULTURE, SEROL NEONATALE & RECH TOXOPLASMOSE LAB, F-75014 PARIS, FRANCE