The sample must be taken  from the finger tip, for a sample on an anticoagulant (EDTA) makes it more difficult to create the thick film.

Before coloring a thick film, it must either be allowed to dry for 24 hours at ambient temperature, or, at worst, at least two hours at 37°C. This fact is hardly compatible with an emergency examination. Certain technical features do facilitate accelerated drying, but they involve material constraints (use of a micro-wave oven). 

The major drawbacks appear at the moment of reading: in fact, the morphology of the parasites is modified and the infected red blood cells, whose morphology is very useful for the diagnosis of species, are lyzed. Furthermore, nor is it possible to count the infected RBCs. Only a very rough evaluation of the parasitemia can be envisaged in terms of a parasite/leukocyte ratio. 
Thus, the thick film technique would seem to be a well tried enrichment technique, which is only viable and sensitive when read by highly trained technicians, but which even in the hands of experts, cannot be used in an emergency context and does not provide a rapid answer to the three questions posed to the biologist:

It will perhaps be necessary to recommend once again a wide use of this method if the announced disappearance of the QBC Malaria Test® is effective, before other techniques, with a low detection threshold, are developed.