In, thin smear microscopy, blood is spread in a layer such that the thickness decreased progressively toward the feathered edge. In the feathered edge, the cells are in a single layer and do not touch one another. In malaria-related household surveys, thin smears are used to identify the species of malaria parasite in settings where it is necessary to estimate levels of P. falciparum, P. Vivax, or other species. This is done after the prevalence has already been determined through thick smear microscopy.
Source: CDC, Measure Evaluation