[The association of dermatomyositis and toxoplasmosis].

IF

negative test: less than 10 UI/ml; doubtful test 10-100 UI/ml; positive test greater than 100 UI/ml. HA: negative test: less than 8 dilutions; doubtful test 16-24; positive test greater than 128. The antibodies kinetics vary with the pattern of the infection (primary infection or reinfection), with the method of identification, and with the subjects. In the case of primary infection, the IgM appear since the first week following the acquisition of the infection; they reach their highest titre at the first month (variability: 15th day-3rd month); they disappear during the fourth month (variability: 2-9 months). The antibodies detected by HA after 2 ME must be reduced by at least 3 dilutions to be significant. The IgG appear later. They are detected at the beginning of the second week by IF or of the 4th month by HA, reach their highest titre at the 4th month by IF (variability: 2-9 months) or at the 9th month by HA (variability: 4th month-2nd year); they then decrease to reach lower titres within the space of 1 or 5 years. The antibodies detected in the case of reinfection are usually of higher titre with a steeper rate of increase, and are more persistent than following a primary infection.