Inflammatory / infectious

Topic Completed: 1 June 2015

Minor changes: 18 February 2021

Copyright: 2015-2021, PathologyOutlines.com, Inc.

PubMed Search: Wuchereria [title]

John K.S.S. Philip, M.D.
Ziyan T. Salih, M.D.
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Cite this page: Philip J, Salih Z. Wuchereria. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixcytologywuchereria.html. Accessed June 20th, 2021.
Definition / general
  • Lymphatic filariasis caused by the nematode (round worm) Wuchereria bancrofti
  • Lymphatic filariasis affects over 120 million people in 73 countries
  • It is endemic in the tropics and subtropics of Asia, Africa, Western Pacific and parts of the Caribbean and South America
  • Currently Haiti, the Dominican Republic, Guyana and Brazil are the only four endemic countries in the Americas
  • In the USA, Charleston, South Carolina was the last known place with lymphatic filariasis
  • The infection was eradicated in the USA in the early 20th century (CDC - Lymphatic Filariasis)
  • Mostly affects the legs
  • Can also occur in the arms, breasts and genitalia
  • Microfilariae have been reported in multiple aspiration sites, cervicovaginal smears, urine, bronchial washings and effusions (Acta Cytol 1983;27:432, Diagn Cytopathol 2011;39:8)
Life Cycle
  • Bite from an infected mosquito introduces third stage infective filarial larvae onto the human skin
  • They penetrate into the bite wound to reach the lymphatics where they reside and develop into adults
  • Adults produce microfilariae that actively move through lymph and blood channels
  • The mosquito ingests this microfilariae during a blood meal
  • After ingestion, the microfilariae develop into an infective larvae through a three stage process inside the mosquito
  • The third stage infective larvae migrate through the mosquito's proboscis and can infect another human when the mosquito takes a blood meal
Diagrams / tables

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Life cycle

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Diagnostic features

Clinical features
  • Vaginal bleeding
  • May be asymptomatic
  • Lymphedema in late stages
  • Standard method to diagnose active infection is microscopic blood smear examination
  • Blood smear collection should be done at night
  • Sensitivity can be increased by concentration techniques
  • Elevated levels of antifilarial IgG4 in blood are seen
  • In chronic cases with lymphedema, lab tests are usually negative
Case reports
  • Diethylcarbamazine (DEC) is the drug of choice in the United States
Microscopic (histologic) description
  • Microfilariae are the diagnostic form
  • Worms or even eggs may be seen
  • Background shows increased eosinophils, neutrophils, plasma cells, macrophages and even granulomas
  • Microfilarial morphology is better appreciated with a Giemsa stain
  • The presence or absence of a sheath and the pattern of nuclei in their tail are the main features used to distinguish the various species
    • The microfilariae of Wuchereria bancrofti are sheathed with no nuclei in the tip of the tail
Microscopic (histologic) images

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Wuchereria bancrofti

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Differential diagnosis
  • Pay attention to the presence or absence of the sheath and the shape and arrangement of the nuclei in the tip of the tail
    • Wuchereria bancrofti (1): Sheath, no nuclei in the tip of the tail
    • Brugia malayi (2): Sheath, 2 distinct nuclei in the tip of the tail
    • Loa loa (3): Sheath, nuclei extending to the tip of the tail
    • Onchocerca volvulus (4): No sheath, no nuclei in the tip of the tail
    • Mansonella perstans (5): No sheath, nuclei extending to the tip of the tail
    • Mansonella ozzardi (6): No sheath, no nuclei in the tip of the tail
    • Mansonella streptocerca (7): No sheath, nuclei extending to the tip of the tail
Additional references
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