|Values are valid only on day of printing.|
Reference Range: <1:20
1:20 - 1:80 Equivocal
> or =1:160 Positive
In the presence of compatible symptoms, a Francisella tularensis antibody titer of 1:160 or greater in an acute specimen supports a presumptive diagnosis of tularemia. However, a titer > or =1:160 may also reflect past infection. An equivocal titer may be due to crossreactive antibodies (Brucella, Yersinia, or Proteus OX19), past infection, or very recent infection. A four-fold rise in titer between acute and convalescent sera is required for definitive serologic diagnosis of tularemia.