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"Dirofilaria immitis" (left) and "Dirofilaria repens" (right)
Dirofilaria immitis (left) and Dirofilaria repens (right)
Scientific classification edit
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Onchocercidae
Genus: Dirofilaria
Railliet & Henry, 1911

Dirofilaria is a genus of nematodes, or roundworms, in the family Onchocercidae. Some species cause dirofilariasis, a state of parasitic infection, in humans and other animals.

There are about 27 species in the genus.[2] These are generally divided into two subgenera, Dirofilaria and Nochtiella.[3]

Some species are well-known parasites, including Dirofilaria immitis, the dog heartworm, Dirofilaria repens, which affects many types of nonhuman mammals, and Dirofilaria tenuis, which usually parasitizes raccoons, but can infect humans, as well.[4]

Human dirofilariasis is generally caused by D. immitis and D. repens. The former can cause pulmonary dirofilariasis, which may have no symptoms. Another form of the infection can be characterized by a painful lump under the skin or infection of the eye.[5] The nematodes are spread by mosquitoes.[6]


From the Latin dīrus (“fearful” or “ominous”) + fīlum (“thread”), Dirofilaria is a genus of nematodes of the superfamily Filarioidea. The first known description of Dirofilaria may have been by Italian nobleman Francesco Birago in 1626 in his Treatise on Hunting: “The dog generates two worms, which are half an arm’s length long and thicker than a finger and red like fire.” Birago erroneously identified the worms as a larval stage of another parasite, Dioctophyme renale. The dog heartworm was named Filaria by American parasitologist Joseph Leidy in 1856, and the genus was renamed Dirofilaria by French parasitologists Railliet and Henry in 1911.[7]


Species in the genus include:[8]


This article uses public domain text from the CDC as cited

  1. ^ "Dirofilaria" (HTML). NCBI taxonomy. Bethesda, MD: National Center for Biotechnology Information. Retrieved 14 January 2019.
  2. ^ Michalski, M. L., et al. (2010). [Identification and phylogenetic analysis of Dirofilaria ursi (Nematoda: Filarioidea) from Wisconsin black bears (Ursus americanus) and its Wolbachia endosymbiont.] Journal of Parasitology, 96(2), 412-419.
  3. ^ Canestri, T. G., S. Pampiglione, & F. Rivasi. (1997). The species of the genus Dirofilaria, Railliet & Henry, 1911. Parassitologia 39(4), 369-374.
  4. ^ Marty, A. M. Dermatologic Manifestations of Filariasis. Medscape.
  5. ^ Klochko, A. Dirofilariasis. Drugs & Diseases. Medscape.
  6. ^ Marty, A. & Neafie, R. "Dirofilariasis", Chapter 16. In: Meyers, W. M., et al. (Eds.) Pathology of Infectious Diseases, Volume 1: Helminthiases. Armed Forces Institute of Pathology, American Registry of Pathology., New Ed, 2000, ISBN 1-881041-65-4.
  7. ^ Etymologia: Dirofilaria. Emerging Infectious Diseases (CDC). February, 2014: Volume 20, Number 2.
  8. ^ Dirofilaria. Global Biodiversity Information Facility (GBIF)