Wuchereria bancrofti

Fiber artifact. Synthetic fiber in thin blood smear (Giemsa's stain, oil immersion). A stained fiber in the field suggests a microfilaria because its outer covering, which stained much lighter, was interpreted as a sheath. However, the small size of this fiber (less than 100 µm) and the lack of characteristic internal structures and organization clearly indicate that this is a fiber artifact and not a microfilaria. Usually, only one such fiber will be found in a blood smear, whereas if a filarial infection was present, typically one would anticipate the presence of more than one microfilaria.