Felis ISSN 2398-2950

Visceral larva migrans

Synonym(s): VLM

Contributor(s): Stephen Barr, Maggie Fisher, Ian Wright

Introduction

  • The term visceral larva migrans (VLM) was originally used to describe larva migrans in all species of animals.
  • The term now normally reserved for larva migrans in humans.
  • Other, related syndromes are ocular larva migrans (OLM), associated with the presence of dying larvae in the retina, covert toxocariasis and cutaneous larva migrans. OLM and covert toxocariasis are associated with Toxocara species, as is VLM normally.
  • Cutaneous larva migrans is normally caused by penetration and migration of hookworm larvae.
  • VLM and cutaneous larva migrans more common in warm climates.
  • Human disease associated with infection with Toxacara larvae is rare in the UK and USA. There is significant seroprevalence (2% approximately in UK) and signs are non specific so it is likely underdiagnosed.
  • As VLM is used to signify specifically Toxocara infection, this review will concentrate hereafter on infection caused by Toxocara spp.
  •  T. canis has traditionally been implicated far more frequently than T. cati Toxocara cati as a cause of toxocariasis in man. However, T.cati is now thought to be a significant contributor to human toxocarosis.
  • Although cats bury their feces, they may defecate in sandpits/boxes where children play and in allotments/gardens where fruit and vegetables are grown for raw consumption.  
  • In the past larvae were generally not speciated, and most were recorded as T. canis by default.
  • Advances in specific identification of larvae using methods such as PCR PCR (Polymerase chain reaction) will elucidate the role of T. cati and cats in toxocariasis.

Presentation

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Pathogenesis

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Symptoms

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Treatment

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Prevention

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Keegan J D & Holland C V (2013) A comparison of Toxocara canis embryonation under controlled conditions in soil and hair. J Helminthol 87 (1), 78-84 PubMed.
  • Overgaauw P A & van Knapen F (2013) Veterinary and public health aspects of  Toxocara spp. Vet Parasitol 193 (4), 398-403 PubMed.
  • Fisher M (2003) Toxocara cati: an underestimated zoonotic agent. Trends in Parasitology 19 (4), 167-170 PubMed.
  • Wolfe A & Wright I P (2003) Human toxocariasis and direct contact with dogs. Vet Rec 152 (14), 419-422 PubMed.
  • Overgaauw P A (1997) Aspects of Toxocara epidemiology: human toxocariasis. Crit Rev Microbiol 23 (3), 215-231 PubMed.

Other sources of information

  • Lewis J W & Laizels R M (1993) Toxocara and Toxocariasis - clinical, epidemiological and molecular perspectives. In: British Society for Parasitology with the Institute of Biology. ISBN0-900490-30-6.


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