IFAT uses the whole parasite body as a series of antigens. Cryostat
and paraffin sections of T. spiralis larvae or muscle tissue of experimentally
infected mice are employed in this test. Sections are incubatedwith
diluted serum and probed with fluorescein-labelled antibodies against
immunoglobulin of the animal species. The reaction of Trichinella larvae
with test serum is evaluated under a fluorescence microscope. Due to
cross-reactions that may occur with antibodies against filariae
(Onchocera spp.), Schistoma mansoni, and some plant parasitic nematodes,
although the technique is sensitive, its application is limited.
Further, investigation of cross-reactive antibodies showed that epitopes
of the heat shock protein from Trichienlla is also recognized by antibodies
from patients with autoimmune disease. Another one of its limitations
is the fact that this test requires a high level of skill, experience,
and expensive laboratory facilities, and serial dilutions of serum must
be made,which makes the test laborious and impractical for the screening
of large number of samples.