Canine Dracunculus Nematode Infection, Toledo, Spain - Volume 26, Number 8—August 2020 - Emerging Infectious Diseases journal - CDC

Canine Dracunculus Nematode Infection, Toledo, Spain - Volume 26, Number 8—August 2020 - Emerging Infectious Diseases journal - CDC

Volume 26, Number 8—August 2020

Dispatch

Canine Dracunculus Nematode Infection, Toledo, Spain

Irina Diekmann, Alaa Aldin Alnassan, Majda Globokar, Nikola Pantchev, Lina Kurzrock, Leticia Hernandez, Javier Lopez, Ricardo Ruano, Silvia Herrero, Georg von Samson-Himmelstjerna, and Jürgen Krücken 

Author affiliations: Freie Universität Berlin, Berlin, Germany (I. Diekmann, G. von Samson-Himmelstjerna, J. Krücken); IDEXX Laboratories, Ludwigsburg, Germany (A.A. Alnassan, M. Globokar, N. Pantchev, L. Kurzrock); IDEXX Laboratories, Barcelona, Spain (L. Hernandez, J. Lopez); Clínica Mediterráneo, Madrid, Spain (R. Ruano, S. Herrero)

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Abstract

A fragment of a Dracunculus-like worm was extracted from the hind limb of a 2-year-old dog from Toledo, Spain. Cytochrome oxidase I and rRNA sequences confirmed an autochthonous mammalian Dracunculus worm infection in Europe. Sequence analyses suggest close relation to a parasite obtained from a North American opossum.

The nematode genus Dracunculus contains 14 accepted species, 10 of which parasitize reptiles. The mammalian parasites include D. fuelleborni, D. lutrae, D. insignis and the human pathogen D. medinensis. Adult female Dracunculus worms are located in the host subcutaneous tissue, especially at the distal extremities (1). Human dracunculosis was an important neglected tropical disease, but successful eradication programs have eliminated the parasites from most endemic countries, with the exception of Chad, Ethiopia, South Sudan, Mali, and Angola. In 2019, only 53 human cases but 1,991 animal infections, predominantly in dogs, were reported worldwide (2). Infection occurs by ingestion of copepods containing third-stage larvae through drinking water or by feeding on paratenic hosts such as frogs, tadpoles, or fish (3,4). No genetic differences can be observed between worms infecting humans and dogs, which now appear to be important reservoir hosts (5). In addition, D. lutrae (host: North American river otter Lontra canadensis) and D. insignis (wide host range, including raccoons, several mustelids, and canids) worms infect predominantly carnivores in North America (6,7).

The taxonomy of Dracunculus is based on morphologic characteristics of male worms, which are rarely available. Therefore, identification based on 18S rRNA has been used for phylogenetic analysis, and identification based on mitochondrial marker cytochrome oxidase C subunit I (COI) has been used for phylogeny, barcoding and intraspecific variation analyses (6).