Dirofilaria immitis

Classification

Taxonomy

• Superfamily: Filarioidea.
• Family: Onchocercidae.
• Genus: Dirofilaria.
• Species: immitis.

Distribution

• Throughout tropical and subtropical regions. Appears to be expanding its range into more temperate climates.
• In the USA, D. immitis  has now been reported from every single state, including Alaska, and there appears to be autochthonous transmission occurring in almost every single state.
• In western Europe, found mainly around the Mediterranean and extending into the Po valley of Italy. Currently unclear as to whether the range in Europe is expanding or remaining static.

Significance

• D. immitis  is probably the most pathogenic of the helminth infections of dogs. The worms within the pulmonary arteries cause severe lung disease that can lead to right heart failure and death. Dogs with heartworm infections will tire upon minimal exercise and die an early death. 
• Hosts include the dog, wolf, dingo, coyote, mustelids (including the ferret), sea lions, and seals.
• Cats can be infected with this worm    , and although cats are not good hosts for supporting the parasite's development (they often have few worms and the infections are often not patent), they can develop severe lung disease and be killed by worms migrating to ectopic sites.
• D. immitis  can also infect people. Larvae entering a human following a mosquito bite can make their way ultimately to the pulmonary vessels. Typically these worms die without causing any clinical signs; the worms die, coil into a small ball, and form what is known as a "coin lesion" in the lungs on a chest radiograph    . These lesions were sometimes mistaken as cancerous growths that have been surgically removed.

Sources

Publications

• Recent references fromPubMed.
• Fukunaga N, Morita T, Sawada M, Matsumoto K, Okamoto M, Uemura T, Haruna A, Shimada A (2005)Cerebral haemorrhage and necrosis due to the aberration of Dirofilaria immitis in a dog.  J Jap Vet Med Assoc58, 751-754.
• Nelson C T, McCall J W, Rubin S B, Buzhardt L F, Doiron D W, Graham W, Longhofer S L, Guerrero J, Robertson-Plouch C, Paul A (2005)Guidelines for the diagnosis, prevention and management of heartworm (Dirofilaria immitis) infection in dogs.  Vet Parasitol133,  255266 PubMed.
• Theis J H (2005) Public health aspects of dirofilariasis in the United States. Vet Parasitol133, 157-180 PubMed.
• Yoon H Y, Jeong S W, Kim J Y, Han H J, Jang H Y, Lee B, Namkung H S (2005)The efficacy of surgical treatment with flexible alligator forceps in dogs with heartworm infection.  J Vet Clinics22, 309-313.
• Kang S S, Kim J H, Kwon Y B, Choi S H (2002)A harbor seal infection with Dirofilaria. J Vet Clinics19, 92-94.
• Theis J H, Gilson A, Simon G E, Bradshaw B, Clark D (2001)Case report: unusual location of Dirofilaria immitis in a 28-year old man necessitates orchiectomy.  Am J Trop Med Hyg64, 317-322 PubMed.
• Narine K, Brennan B, Gilfillan I, Hodge A (1999)Pulmonary presentation of Dirofilaria immitis (canine heartworm) in man.  Eur J Cardio-Thoracic Surg16, 475-477.
• McCall J W (1998)Dirofilariasis in the domestic ferret.  Clin Tech Small Anim Pract13, 109-112. 
• Lichtenfels J R, Pilitt P A, Kotani T, Powers K G (1985)Morphogenesis of developmental stages of Dirofilaria immitis (Nematoda) in the dog.  Proc Helm Soc Wash52, 98-113.
• Beusse D O, Asper E D, Baucom J N, Searles S W (1977)Diethylcarbamazine citrate for prevention of heartworm (Dirofilaria immitis) in the California sea lion (Zalophus californianus).  Vet Med Small Anim Clin72, 470-471.