Toxascaris leonina

TOXOSCARIS LEONINA

T. leonina is a little smaller (up to 10cm), but otherwise similar in appearance to T. canis. With a female worm, the easiest way to tell them apart is to cut it open and examine the eggs under the microscope. The eggs of Toxoscaris are smooth and pale; whilst those of Toxocara species are dark and pitted.

The biology of T. leonina is generally similar to that of T. canis, except:

• it infects both felidae and canidae
• in the final host:
  • there is no prenatal transmission
  • there is no transmammary transmission
  • there is no hepato-tracheal migration
• in 'paratenic' hosts:
  • develops to L3 in tissues (the 'paratenic' hosts therefore are really facultative intermediate hosts).

Transmission is via ingestion of the embryonated egg or an infected 'paratenic' host. The zoonotic potential is uncertain, but T. leonina is not thought to be as hazardous as T. canis.