Changes

====Cycle 4====

====Cycle 4====

The final life cycle involves transmission of L3 larvae to pups through the milk. Hypobiotic L3 larvae are reactivated and are either already present in the mammary glands or travel to them and are capable of passing in the milk during the first 3 weeks of lactation. There is no further migration in the pup when the larvae are ingested in this way and the remaining life cycle of the worm is completed in the small intestine of the pup.

The final life cycle involves transmission of L2 larvae to pups through the milk. Hypobiotic L2 larvae are reactivated and are either already present in the mammary glands or travel to them and are capable of passing in the milk during the first 3 weeks of lactation. There is no further migration in the pup when the larvae are ingested in this way and the remaining life cycle of the worm is completed in the small intestine of the pup.

As well as the above life cycles ''T. canis'' can infect paratenic hosts such as mice, rats and some birds. Events occur just as in the older dog, i.e. larvae migrate → liver → lungs → heart → somatic tissues → granulomatous reactions → 'waiting phase'; but in this case, the somatic larvae are waiting for the animal that they are in (which is acting as a '''paratenic host''') to be eaten by a dog, fox, wolf or other canid, where they will establish as adults or somatic larvae (depending on the age of the predator). This explains how humans (as warm-blooded non-canid animals) enter into the epidemiological picture. The prepatent period of ''T. canis'' is 4 - 5 weeks in the canid host.

As well as the above life cycles ''T. canis'' can infect paratenic hosts such as mice, rats and some birds. Events occur just as in the older dog, i.e. larvae migrate → liver → lungs → heart → somatic tissues → granulomatous reactions → 'waiting phase'; but in this case, the somatic larvae are waiting for the animal that they are in (which is acting as a '''paratenic host''') to be eaten by a dog, fox, wolf or other canid, where they will establish as adults or somatic larvae (depending on the age of the predator). This explains how humans (as warm-blooded non-canid animals) enter into the epidemiological picture. The prepatent period of ''T. canis'' is 4 - 5 weeks in the canid host.