Ancylostoma spp

From Dog
Eggs of A. caninum, visualized under light microscopy[1]
Adult Ancylostoma spp attached to the lining of the small intestine[2]

Ancylostoma spp (hookworm) are the most common zoonotic parasitic nematode of dogs and cats and are found worldwide[3].

Co-infections with other gastrointestinal parasites such as Toxocara canis and Uncinaria stenocephala is common[4].

Species which are pathogenic to dogs include:

  • Ancylostoma caninum (human eosinophilic enteritis)[5]
  • Ancylostoma braziliense[6]
  • Ancylostoma ceylanicum[7]
  • Ancylostoma duodenale

Anyclostoma are a relatively robust parasite and several hundred genes change their expression during the worm's transition from a free living to a parasitic larva[8]. They possess a heat-shock protein-based cuticle which allows them to survive harsh environments off-host[9]. They are, however, prone to parasitism by nematophagous symbiont fungi, such as Monacrosporium thaumasium, Arthrobotrys robusta and Duddingtonia flagrans[10].

They have a direct life cycle with dogs becoming infected through ingestion of eggs in soil and coat hair, or through skin penetration by infective larvae. Sharp rostral teeth are used for attachment and anticoagulant peptides are used by this nematode to feed on their host[11]. Eggs are activated through gastric proteolytic enzymes and larvae penetrate the mucosa of the intestine and undergo extensive tissue migration throughout the body before residing in the small intestine, where they reproduce and shed eggs[12]. The eggs pass in the feces and hatch in the soil. The first stage larva feeds on bacteria and molts twice to form the non-feeding, infective third stage[13].

Similar to Toxocara canis, A. caninum infective larvae can also temporarily abort maturation and enter an arrested state (hypobiosis) within somatic tissues, reactivating in response to physiological changes such as pregnancy[14].

Infections in young dogs normally result in characteristic underweight, pot-bellied puppies, which are often anemic. Deaths associated with heavy infestations in young dogs is common. Adult dogs are often asymptomatically infected, although poor coat, polyphagia and anemia can also occur.

Blood tests usually show neutrophilia and eosinophilia, particularly with A. caninum, whereas A. braziliense often presents with leucopenia[15].

Diagnosis is usually based on coprological examinations using fecal floatation devices[16]. The eggs of A. braziliense are significantly smaller than the eggs of A. caninum and A. tubaeforme and makes identification relatively simple for experienced clinicians using light microscopy[17].

Supportive diagnosis can be made with ELISA assays of feces and blood samples, and PCR assays can be used for accurate speciation of the parasite.

Treatment is usually effective with milbemycin oxime[18], moxidectin[19], ivermectin and most proprietary benzimidazoles or thiophenes (e.g. febantel)[20].

References

  1. Catnmore
  2. Encyclopedia of Life
  3. Coelho WM et al (2011) Occurrence of Ancylostoma in dogs, cats and public places from Andradina city, São Paulo state, Brazil. Rev Inst Med Trop Sao Paulo 53(4):181-184
  4. Bwalya EC et al (2011) Prevalence of canine gastrointestinal helminths in urban Lusaka and rural Katete Districts of Zambia. Prev Vet Med 100(3-4):252-255
  5. Loukas A et al (1992) Detection of antibodies to secretions of Ancylostoma caninum in human eosinophilic enteritis. Trans R Soc Trop Med Hyg 86:650–653
  6. Liotta JL et al (2012) Prevalence of Ancylostoma braziliense in Dogs from Alachua and Marion Counties, Florida, United States. J Parasitol Mar 6
  7. Mahdy MA et al (2012) Prevalence and zoonotic potential of canine hookworms in Malaysia. Parasit Vectors 5:88
  8. Datu BJ et al (2008) Transcriptional changes in the hookworm, Ancylostoma caninum, during the transition from a free-living to a parasitic larva. PLoS Negl Trop Dis 2(1):e130
  9. Krepp J et al (2011) Characterisation of hookworm heat shock factor binding protein (HSB-1) during heat shock and larval activation. Int J Parasitol 41(5):533-543
  10. Carvalho RO et al (2009) Predatory activity of nematophagous fungi on infective larvae of Ancylostoma sp.: evaluation in vitro and after passing through the gastrointestinal tract of dogs. J Helminthol 83(3):231-236
  11. Jiang D et al (2011) Ac-AP-12, a novel factor Xa anticoagulant peptide from the esophageal glands of adult Ancylostoma caninum. Mol Biochem Parasitol 177(1):42-48
  12. Bowman, DD (2009) Georgis' parasitology for veterinarians. 9th edn. Elsevier Saunders, Missouri. pp:179-181
  13. Wang Z et al (2010) Characterizing Ancylostoma caninum transcriptome and exploring nematode parasitic adaptation. BMC Genomics 11:307
  14. Stone WM & Girardeau M (1968) Transmammary passage of Ancylostoma caninum larvae in dogs. J Parasitol 54(3):426–429
  15. Dias SR et al (2013) Evaluation of parasitological and immunological aspects of acute infection by Ancylostoma caninum and Ancylostoma braziliense in mixed-breed dogs. Parasitol Res Mar 14
  16. Cringoli G et al (2011) Ancylostoma caninum: calibration and comparison of diagnostic accuracy of flotation in tube, McMaster and FLOTAC in faecal samples of dogs. Exp Parasitol '128(1):32-37
  17. Lucio-Forster A et al (2012) Morphological Differentiation of Eggs of Ancylostoma caninum, Ancylostoma tubaeforme, and Ancylostoma braziliense From Dogs and Cats in the United States. J Parasitol Mar 6
  18. Snyder DE & Wiseman S (2012) Dose confirmation and non-interference evaluations of the oral efficacy of a combination of milbemycin oxime and spinosad against the dose limiting parasites, adult cat flea (Ctenocephalides felis) and hookworm (Ancylostoma caninum), in dogs. Vet Parasitol 184(2-4):284-290
  19. Taweethavonsawat P et al (2010) Experimental infection with Ancylostoma ceylanicum in dogs and efficacy of a spot on combination containing imidacloprid 10% and moxidectin 2.5% (Advocate/Advantage Multi, Bayer Animal Health). Parasitol Res 106(6):1499-1502
  20. Taweethavonsawat P et al (2010) Efficacy of a combination product containing pyrantel, febantel and praziquantel (Drontal Plus Flavour, Bayer Animal Health) against experimental infection with the hookworm Ancylostoma ceylanicum in dogs. Parasitol Res 106(2):533-537