Volume 15, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



The decline in infectivity of cercariae was studied under controlled laboratory conditions considered favorable for cercarial survival. Cercariae of known age were tested by mouse exposure challenge at intervals up to 30 hours from the time they were shed from snails. Infectivity decreased with time and the decrease was rapid. About eight hours after the cercariae were shed, one-half the infectivity had been lost. Since there was no detected loss of infectivity in the first three hours, the time for infectivity to fall to one-half of the maximum level was less than five hours. Infectivity was about one-tenth the initial level after 14–15 hours.

Since conditions for cercarial survival in the experiments were relatively favorable, it can be expected that under field conditions, which are almost always more rigorous, the cercarial half-life is probably only a few hours even in the absence of predators.


Article metrics loading...

The graphs shown below represent data from March 2017
Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error