Toxocara species and Baylisascaris

Paul Auwaerter, M.D.
Toxocara species and Baylisascaris is a topic covered in the Johns Hopkins ABX Guide.

To view the entire topic, please or .

Official website of the Johns Hopkins Antibiotic (ABX), HIV, Diabetes, and Psychiatry Guides, powered by Unbound Medicine. Johns Hopkins Guide App for iOS, iPhone, iPad, and Android included. Explore these free sample topics:

-- The first section of this topic is shown below --

MICROBIOLOGY

  • Toxocara spp.
    • Worldwide helminthic infection of humans, agent nematodes:
      • Toxocara canis (dog roundworm)
      • Toxocara cati (cat roundworm), less common
    • Humans are infected as accidental hosts by ingesting eggs from contaminated soil [life cycle Fig. 1] by feces of infected dogs or cats.
      • It usually occurs in overcrowded, poor living conditions with dogs or cats.
        • Ingested eggs evolve to larval forms penetrating intestinal mucosa with subsequent spread to a variety of body organs (visceral larval migrans [VLM] and/or eyes, ocular larval migrans [OLM]) in arrested development, no ongoing production. Host inflammatory reactions produce symptoms as parasites die off.
        • Human infection does not yield egg production; hence inspection of stool O&P is pointless.
  • Baylisascaris procyonis (raccoon roundworm worldwide, including the U.S.) has also been reported to cause VLM (mainly CNS forms, eosinophilic meningoencephalitis) and OLM.
  • Note: cutaneous larval migrans (CLM) is caused by several nematodes, most commonly hookworm (Ancylostoma braziliense).

-- To view the remaining sections of this topic, please or --

MICROBIOLOGY

  • Toxocara spp.
    • Worldwide helminthic infection of humans, agent nematodes:
      • Toxocara canis (dog roundworm)
      • Toxocara cati (cat roundworm), less common
    • Humans are infected as accidental hosts by ingesting eggs from contaminated soil [life cycle Fig. 1] by feces of infected dogs or cats.
      • It usually occurs in overcrowded, poor living conditions with dogs or cats.
        • Ingested eggs evolve to larval forms penetrating intestinal mucosa with subsequent spread to a variety of body organs (visceral larval migrans [VLM] and/or eyes, ocular larval migrans [OLM]) in arrested development, no ongoing production. Host inflammatory reactions produce symptoms as parasites die off.
        • Human infection does not yield egg production; hence inspection of stool O&P is pointless.
  • Baylisascaris procyonis (raccoon roundworm worldwide, including the U.S.) has also been reported to cause VLM (mainly CNS forms, eosinophilic meningoencephalitis) and OLM.
  • Note: cutaneous larval migrans (CLM) is caused by several nematodes, most commonly hookworm (Ancylostoma braziliense).

There's more to see -- the rest of this topic is available only to subscribers.

Last updated: February 5, 2023