The sheath of a microfilaria is a baglike structure. On properly processed smears,
the sheath is either:
- Present - Brugia malayi, Brugia timori, Wuchereria bancrofti, Loa loa
- Absent - Mansonella perstans, Mansonella ozzardi, Mansonella streptocerca, Onchocerca volvulus
Regarding color of a sheath:
- Demonstrates a bright pink color on Giemsa - Brugia malayi
- Usually colorless on Giemsa - Brugia timori, Wuchereria bancrofti, Loa loa
Note: The image detail is an example of a colorless sheath.
22. CDC/Melvin. Detail of Image #21534. "Under a magnification of 1700X, this photomicrograph revealed some of the ultrastructural features exhibited at the posterior end of a Loa loa microfilaria. In this view, you are able to see the sheath that encased the tail region, as well as the nuclei contained inside the tail." PHIL public domain. Created 1966. Accessed April 6, 2023. https://phil.cdc.gov/Details.aspx?pid=21534
