Heartworm

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Heartworm
D. immitis in a dog heart

D. immitis in a dog heart

Systematics
Trunk : Roundworms (Nematoda)
Order : Spirurida (Spirurida)
Superfamily : Filaria (Filarioidea)
Family : Onchocercidae
Genre : Dirofilaria
Type : Heartworm
Scientific name
Dirofilaria immitis
Leidy , 1856

The heartworm ( Dirofilaria immitis ), a nematode from the superfamily of filaria , is the causative agent of heartworm disease of the dog . The worm is obligatorily two host. Mosquitoes transmit the infectious third larvae. From this , the adult heartworms, approx. 1 mm thick and approx. 20-30 cm long, develop in the heart of the dog .

distribution

Heartworm disease occurs wherever its vector is widespread, especially in the tropics , the subtropics and the warmer regions of the temperate zone . In Europe, the islands of the Canary Archipelago , southern France , Spain and the Italian Po Valley are particularly hard hit. Diseases in the Mediterranean have been documented since 1885. In North America, the southern states along the Atlantic and Gulf coasts of the United States are particularly affected. The parasite is also found in Central and South America , all of South Asia, Australia and Africa.

Although it is primarily a dog disease, this parasite can also affect cats, ferrets, foxes, coyotes, wolves, dingoes, and humans.

To date, 1,700 infections have been detected in humans. In Italy, 298 cases were documented from 1885 to 2000.

morphology

The males are 120-180 mm long and 700-900 μm wide, the females 250-300 mm long and 1000-1300 μm wide. The microfilariae have a length of 290–330 and a width of 5–7 μm. The female's vulva is about 2700 μm from the head end, the anus 150 μm from the tail end. The cuticle is smooth in both sexes, exceptions are the head, where there are six papillae, and in the male the ventral side of the tail area, which has longitudinal grooves.

Life cycle

Heartworm life cycle

Mosquitoes ingest infectious larvae (microfilariae) with the blood of infected animals. In the mosquito they develop into the third larvae that are transferred to another dog during the act of sucking. In the subcutaneous tissue of the new host, they molt into the fourth larvae, which migrate into the bloodstream and primarily settle in the pulmonary artery . With severe infestation, they can spread to the right half of the heart or even into the vena cava . There the larvae develop into adult worms (macrofilariae). These again produce new larvae (microfilariae) that swim in the bloodstream.

Macrofilariae are bisexual, ie the female parasites give birth to the larvae, which can only develop into the third larvae that are infectious for the dog in the mosquito. Accordingly, the number of macrofilariae depends on the number of third larvae transferred when the mosquito sucks.

literature

  • Susanne Geyer, Arthur Grabner: The veterinary assistant. Textbook and guide for training. Schlütersche. Hannover 2002. ISBN 3-87706-541-4

See also

Web links

Commons : Dirofilaria immitis  - collection of images, videos and audio files

Individual evidence

  1. a b H.-J. Bürger et al .: Veterinary Parasitology . Georg Thieme Verlag, 6th edition 2006, ISBN 978-3-8304-4202-8 , p. 503.
  2. ^ Herbert Auer: Dirofilariosis in humans. In: Denisia 13. Biology Center of the Upper Austrian State Museum, September 17, 2004, pp. 463–471 , accessed on December 14, 2017 (German).
  3. Stephen J. Ettinger and Edward C. Feldman: Textbook of Veterinary Internal Medicine . WB Saunders Company, 4th Edition 1995, ISBN 0-7216-6795-3 .
  4. ^ A b Oliver Wilford Olsen: Animal Parasites: Their Life Cycles and Ecology . Courier Corporation, 1986, ISBN 978-0486651262 , pp. 488-489.
  5. SK Borthakur et al .: Prevalence and molecular epidemiological data on Dirofilaria immitis in dogs from Northeastern States of India. In: TheScientificWorldJournal. Volume 2015, 2015, p. 265385, doi : 10.1155 / 2015/265385 , PMID 25685835 , PMC 4320797 (free full text).
  6. S. Pampiglione, F. Rivasi: Human dirofilariasis due to Dirofilaria (Nochtiella) repens: an update of world literature from 1995 to 2000. In: Parassitologia. Volume 42, Number 3-4, December 2000, pp. 231-254, PMID 11686084 (Review).
  7. MW Service, RW Ashford et al.: Encyclopedia of arthropod-transmitted infections of man and domesticated animals Wallingford, Oxon, UK; New York, NY, USA: CABI Pub., 2001. ISBN 0851994733 p. 145 .