Uncinaria stenocephala

Uncinaria stenocephala is a nematode that parasitizes dogs, cats, and foxes as well as humans. It is rare to find in cats in the United States. Uncinaria stenocephala is the most common canine hookworm in cooler regions, such as Canada and the northern regions of the US, where it can be found primarily in foxes (40%).[1] U. stenocephala is also one of the most common hookworms in the UK, called the northern hookworm, however it has a rather low prevalence.[2] U. stenocephala is also considered to be zoonotic hookworms because they live in animals but can be transmitted to humans.[3]

Strongylida stenocephala
Scientific classification
Kingdom:
Animalia
Phylum:
Nematoda
Class:
Secernentea
Subclass:
Strongylida
Order:
Rhabditia
Family:
Ancylostomatidae
Genus:
Uncinaria
Species:
U. stenocephala
Binomial name
Uncinaria stenocephala
(Railliet, 1884)

Life cycle

The host ingests an infective third stage larva. The larva matures to the adult in the small intestine. Eggs are laid in the small intestine and pass out with the feces. The prepatent period is about 15 to 17 days. The eggs hatch in the soil and the larvae molt twice to reach the infective third-stage.[4] Infections worsen and amplify when dogs who are regularly kept outside are not routinely dewormed.[5]

Adult worms may live for 4 to 24 months in the small intestine. Dog and cat hookworms range in size from 10 to 20 mm by 0.4 to 0.5 mm and the eggs are 71 to 93 μm by 35 to 58 µm.[4] A study shown a high number of eggs per female U. stenocephala worm was measured at over 5,000 eggs.[6]

Adult parasites are most often found in their hosts' small intestine.

A second type of infection occurs with transdermal larval infection into the dog's skin, usually made possible by warm weather and humidity which allows the larvae to grow in the environment.[5] These transdermal infections are not very significant in U. stenocephala because about 2.3% ± 1.3% of infective larvae actually reach the small intestine to finish its life cycle.

Diagnosis

Diagnostic Stage:

  • Eggs are found in fecal flotation.
  • Eggs measure 75 um long by 45 um wide.

Common Diagnostic Test

  • Fecal float to recover eggs.

Clinical Signs:

  • U. stenocephala ingests plasma protein rather than whole blood, so the loss of nutrients is evident.
  • All hookworms suck blood, they are capable of removing 0.1mL of blood per worm, per 24-hour period.
  • Light infections are asymptomatic.
  • Infected pups may present with pale mucus membranes and anemia, ill thrift, failure to gain weight, poor hair coat, dehydration, and dark, tarry diarrhea (melena). Puppies harboring many worms will develop an acute normocytic, normochromic anemia followed by hypochromic, microcytic anemia due to iron deficiency. Without immediate intervention, these animals may die of the infection. Those that survive may continue as "poor doers" with chronic anemia.[4]

U. stenocephala is considered a zoonotic hookworm and can cause a few different diseases in humans, including cutaneous larva migrans.[7] Humans become infected when the larvae penetrate unprotected skin due to contaminated animal feces in the environment.

Treatment/Prevention

Effective treatment of U. stenocephala includes proper medical treatment and the proper choice of anthelmintic. It is recommended for infected animals to have their feces examined 3 weeks after treatment is complete.[5]

Febantel, Febantel/Pyrantel embonate, Fenbendazole, Ivermectin, Mebendazole, Pyrantel Pamoate

Heartworm prevention products that include Ivermectin/Pyrantal/Praziquantel or Moxidectin are good at controlling U. stenocephala in dogs.[1]

References
  1. "Hookworms in Small Animals - Digestive System". Merck Veterinary Manual. Retrieved 2019-04-26.
  2. "Canine hookworm dermatitis (uncinariasis)". veterinary-practice.com. Retrieved 2019-04-26.
  3. "CDC - Zoonotic Hookworm". www.cdc.gov. 2019-04-25. Retrieved 2019-12-11.
  4. "Intestinal Parasites - Hookworms". Companion Animal Parasite Council. Retrieved 8 December 2011.
  5. Chu, Shirley; Myers, Sherry L.; Wagner, Brent; Snead, Elisabeth C.R. (August 2013). "Hookworm dermatitis due to Uncinaria stenocephala in a dog from Saskatchewan". The Canadian Veterinary Journal. 54 (8): 743–747. ISSN 0008-5286. PMC 3711160. PMID 24155473.
  6. Rep, B. H.; Bos, R. (1979-10-01). "Enige epidemiologische aspecten van Uncinaria stenocephala infectie in Nederland" [Epidemiological aspects of Uncinaria stenocephala infections in the Netherlands]. Tijdschrift voor Diergeneeskunde. 104 (19): 747–758. ISSN 0040-7453. PMID 573511.
  7. Postigo, I.; Martinez, J.; Guisantes, J.A. (2006). "Uncinaria stenocephala: Assessment of antigens for the immunodiagnosis of canine uncinariosis". Experimental Parasitology. 114 (3): 215–219. doi:10.1016/j.exppara.2006.03.012. PMID 16682029.
  • Foreyt, W. J. (2001). Veterinary parasitology reference manual. (5 ed.). Ames, IA: ZBlackwell publishing.
  • Plumb, D. C. (2008). Plumb's veterinary drug handbook. Wiley-Blackwell.
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