Les difficultés d'interprétation des sérologies parasitaires (en dehors de la toxoplasmose)

Positive diagnosis of parasitological diseases relies on the detection of the causative agent in the biological fluids. However, in many cases, only indirect diagnosis is possible. Serology is thus very helpful in the diagnosis of parasitic diseases when parasites are not adapted to the human host (visceral Larva migrans syndrome), when they remain in the tissues (hydatid disease) or when they are characterized by a long-lasting migration phase (distomiasis). Several methods allowing the detection of specific antibodies have been developed and some commercial kits are available. Assays which will be used have to be adapted to considered parasites and association of several tests is often necessary. Thus, positivity of screening test(s) will be checked by confirmation test(s). If negative, and particularly if there is an important clinical suspicion, tests must be repeated because of possible late seroconversions. Sensibility of serological assays is generally correct, but specificity is often insufficient. Sometimes, they cannot give information about parasite species (filariasis, schistosomiasis) and many cross reactions are described during tissular helminthiasis. So, results of serological diagnosis have to be interpreted according to laboratory standards and to clinical and epidemiological data.