Life cycle

LIFE CYCLE

  • Female lays about 16,000 eggs per day. Bionomics and development of larvae is similar to Strongyle spp.
  • Desiccation is very lethal to hook worm larvae so the more suitable place for survival of hook worm larvae is slightly sandy and moist soil.
  • L1 emerges from egg in about 3 days and moult to become L2 in 6 days. Under optimal (23 to 30°C) condition infective stage is reached in one-week time. Infection of final host either by oral ingestion of L3 or skin penetration by L3.
  • In dogs and cats oral ingestion is very common because they have a habit of licking the grass. Skin penetration is common in human being and cattle.

In A.caninum, infection occurs in four ways,

Oral ingestion

  • Following oral ingestion of infective larvae either directly develops to mature or the infective larvae penetrate the oral mucosa and follow the tracheal route of migration.
  • Finally the infective stage reaches the intestine and develops to adult.

Skin penetration

  • Following skin penetration, the infective larvae reaches the lungs via circulation and then follow the tracheal route of migration.
  • Finally enter the intestine where it develops to adult.

Prenatal infection

  • In older bitches following oral ingestion or skin penetration, a few larvae directly develops to adult but majority of the larvae follows somatic migration and remain dormant in the tissue until pregnancy.
  • In the pregnant bitches dormant larvae is activated by the hormonal influence.
  • These activated larvae enter the foetus via placental circulation. The worms do not mature until birth of the pups.
  • They mature with in 30 days of birth of pups and eggs can be seen in faeces. Prenatal infection is common in pups.

Transmammary infection

  • The larvae passed to pups via colostrum they directly develop to adult without any migration.
  • Paratenic host may also involved (rodents) infection is by ingestion of infected rodents.

Click here to view animation
Last modified: Tuesday, 19 June 2012, 9:16 AM