Table 2.

Detection of Q fever infection in paired sera

TestNo. positive (%)
Acute-phase sera (S1)Second sera (S2)
IgM IFATa 5/22 (23)22/22 (100)
IgM ELISA6/22b (27)22/22 (100)
CFT1/22 (5)22/22 (100)
  • a All paired sera showed at least a fourfold rise in titer by IgM IFAT.

  • b One acute serum was IgM ELISA positive (ratio, 1.78) and IgM IFAT negative (ratio, <12).