[Tests for evaluating the effectiveness of pediculicides: importance and limitations].

The obligation to prove pediculicides efficacy is relatively recent. Two tests are required by the authorities to obtain registration. In vitro test (with Pediculus humanus humanus) is the first step to evaluate the efficacy of new molecules. It must be followed by bio-clinical tests (with infested children by Pediculus humanus capitis). For those tests the authors advise to respect the "three units rule": unit of time (no more than 2 days for the test), unit of place (same environment) and unit of action (only one team to apply and evaluate products). This type of tests is possible only in countries with high infestation (at least 60% of prevalence). A third test is consequently advised, the ex vivo test using Pediculus humanus capitis obtained from infested children in France. This test can be useful also to re-evaluate current products in the light of increased resistance or decreased sensitivity of the lice. Finally some other tests can be advised to prove some other activities like remanence or repellent properties or to estimated lice resistance.