- Tissue or lymphohematogenous system infection by adult or larval roundworms (nematodes)
- Infections can be subclinical (asymptomatic) or present with acute/chronic manifestations.
- Filarial infections (Filarioidea superfamily)
- Wuchereria bancrofti (bancroftian filariasis)
- Brugia malayi (Malayan filariasis)
- Brugia timori (Timorian filariasis)
- Loa loa (eye worm)
- Onchocerca volvulus (river blindness, onchocerciasis)
- Mansonella perstans, Mansonella ozzardi, Mansonella streptocerca (mansonellosis)
- Other tissue nematode infections
- Dracunculus medinensis (Guinea worm, dracunculiasis)
- Ancylostoma braziliense, Ancylostoma caninum (cutaneous larva migrans, creeping eruption)
- Toxocara canis, Toxocara cati (visceral larva migrans [VLM] or ocular larva migrans [OLM], toxocariasis)
- Gnathostoma hispidum, Gnathostoma spinigerum (gnathostomiasis)
- Dirofilaria immitis (dog heartworm), Dirofilaria repens, Dirofilaria tenuis (dirofilariasis)
- Systems affected: cardiovascular, gastrointestinal, hematologic/lymphatic/immunologic, musculoskeletal, nervous, renal/urologic, skin/exocrine
- W. bancrofti: tropics worldwide; mosquito vector (Culex, Mansonia, Anopheles, Aedes)
- B. malayi: Southeast Asia and Pacific islands; mosquito vector
- B. timori: Indonesia; mosquito vector
- L. loa: Africa and India; deer fly vector (Chrysops spp.)
- O. volvulus: Africa, Middle East, and South America; blackfly vector (Simulium)
- Mansonella spp.: Central Africa and South America; midge vector (Culicoides)
- D. medinensis: Ethiopia, Ghana, Mali, Sudan; contaminated water
- A. braziliense, A. caninum: tropics and subtropics worldwide; contaminated soil
- T. canis, T. cati: worldwide; contaminated food or soil
- G. hispidum, G. spinigerum: Asia, emerging in Central/South America; undercooked intermediate host (fish, eel, frog, reptiles, or birds) or contaminated water (copepods)
- D. immitis: worldwide; mosquito vector
- D. repens: Europe, Southeast Asia, and Africa; mosquito vector
- D. tenuis: North America; mosquito vector
- Prevalence in endemic areas increases with age. Worm burden increases with exposure over time.
- Lymphatic filariasis affects ~120 million and is the second leading cause of permanent disability worldwide. Infection is likely first acquired in childhood; up to 1/3 asymptomatically infected by age 5 years
- Onchocerciasis affects 37 million and is the second leading cause of blindness in the world.
- Estimated 3,000 to 10,000 were infected with dracunculiasis due to focused eradication program.
- Toxocariasis (VLM/OLM) is more prevalent in children.
Etiology and Pathophysiology
- Filarial infections—adult nematodes live in subcutaneous tissues and lymphatic vessels for years. They produce microfilariae offspring which circulate in blood or tissues until ingested by arthropod vectors. In this intermediate host, they develop into infective larval stages which are then transmitted to the definitive human host.
- Carnivores are natural hosts for certain nematodes that are unable to complete their life cycles in humans, who are accidental hosts.
- In human tissue, worms mature over 6 to 12 months and survive up to 15 years.
- Geographic exposure to arthropod vectors
- Infections can be acquired from contaminated food, water, or soil.
- Domestic/wild animal exposure
- Travel precautions in endemic areas, arthropod bite precautions, avoid infected rivers and streams, avoid infected food/water sources and contaminated soils, filter water appropriately
- Vector control: bed nets, larvicides, insecticides, repellent, clothing
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Domino, Frank J., et al., editors. "Roundworms, Tissue." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2020. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688529/all/Roundworms_Tissue.
Roundworms, Tissue. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2020. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688529/all/Roundworms_Tissue. Accessed June 10, 2023.
Roundworms, Tissue. (2020). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (27th ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688529/all/Roundworms_Tissue
Roundworms, Tissue [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2020. [cited 2023 June 10]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688529/all/Roundworms_Tissue.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Roundworms, Tissue ID - 1688529 ED - Domino,Frank J, ED - Baldor,Robert A, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688529/all/Roundworms_Tissue PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -