Filariasis is a filarial infection caused by parasitic nematodes (roundworms) belonging to the superfamily Filarioidea, spread by different vectors [2]. The most common type is lymphatic filariasis, caused by three Filaria species and transmitted by mosquitoes; other forms include onchocerciasis (river blindness) caused by Onchocerca volvulus, Loa loa filariasis (loiasis), mansonelliasis caused by three Mansonella species, and dirofilariasis caused by two Dirofilaria species [2]. Eight known filarial worms use humans as their definitive host [2].
Disease overview
Parasitic Evidence-backed information EN 5/7 applicable sections · ZH 5/7 applicable sections Updated Oct 23, 2026
Filariasis is a parasitic infection caused by filarial nematodes (roundworms) transmitted by different arthropod vectors, and it is classified among neglected tropical diseases. The most common form, lymphatic filariasis, is spread by mosquitoes carrying worm larvae and represents the leading cause of permanent disfigurement and the second most common cause of long-term disability worldwide [1][2]. Global control programs have been strengthened by ivermectin, which the WHO cites as a key tool enabling the official declaration that lymphatic filariasis is eradicable [3]. Distribution remains heavily concentrated in South and Southeast Asia, with additional burden in African nations and the Americas [2].
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Chyluria, characterized by the passage of chyle into the urine resulting in a milky appearance, is a clinical manifestation of filariasis due to an abnormal communication between the lymphatic and urinary systems. Filariasis is reported as the most frequent cause of chyluria [4].
Filariasis is included in the list of neglected tropical diseases, with lymphatic filariasis carrying the heaviest burden [2]. In the year 2000, an estimated 199 million infection cases of lymphatic filariasis were predicted, with roughly 3.1 million cases in the Americas and approximately 107 million in South-East Asia; about 52% of global cases were concentrated in Bangladesh, India, Indonesia, and Myanmar combined [2]. African nations accounted for around 21% of cases and showed a decreasing trend over the 19-year period from 2000 to 2018, while the global burden remained concentrated in Southeast Asia [2].
Filariasis is transmitted by infected arthropod vectors; for lymphatic filariasis and related mosquito-borne forms, the vectors are mosquitoes of the genera Aedes, Culex, Anopheles, and Mansonia [2]. Climate change has been identified as an emerging influence on the spread of the parasitic disease and its vectors [1][2].
Ivermectin, a parasiticide originally established in veterinary medicine, has become one of the most effective tools in control programs against human filarial diseases since the 1980s; it is provided at no cost, effective against microfilariae (thereby blocking transmission), and can be administered annually as a single oral dose with virtually no side effects [3]. These properties contributed to the WHO's official declaration that lymphatic filariasis (along with onchocerciasis) is eradicable among the major endemic diseases worldwide [3].
- 1 Lourens GB et al. Lymphatic Filariasis. Nurs Clin North Am. 2019 Jun. PMID: 31027660. doi: 10.1016/j.cnur.2019.02.007. PubMed: https://pubmed.ncbi.nlm.nih.gov/31027660/
- 2 Wikipedia contributors. Filariasis - Wikipedia [Internet]. Wikipedia. cited 3 Sept 2026. Available from: https://en.wikipedia.org/wiki/Filariasis
- 3 Richard-Lenoble D et al. Ivermectin and filariasis. Fundam Clin Pharmacol. 2003 Apr. PMID: 12667230. doi: 10.1046/j.1472-8206.2003.00170.x. PubMed: https://pubmed.ncbi.nlm.nih.gov/12667230/
- 4 Kbaier I et al. [Chyluria]. Tunis Med. 2002 Nov. PMID: 12664512. PubMed: https://pubmed.ncbi.nlm.nih.gov/12664512/
- B74
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