What laboratory method is most commonly used to identify motile nematode larvae in feces?

The direct smear method is particularly effective for identifying motile nematode larvae in feces because it allows for the examination of the sample under a microscope shortly after collection. When using this method, a small amount of fecal material is mixed with a liquid (often saline) on a microscope slide, making it easy to observe the movement of larvae. The larvae are motile, which makes them readily identifiable when viewed microscopically.

This method is favored for its simplicity and speed, as it provides immediate results without the need for prolonged processing that other methods may require. In contrast, the flotation method is more suited for detecting eggs, while the fecal sedimentation method is effective for certain specific types of eggs and cysts but might not effectively capture the motility of larvae. The culture method, while useful for producing larvae from eggs, involves additional steps and takes longer to yield results, making it less practical for immediate identification of motile larvae in a fecal sample.