How do you determine which birds are carrying the schistosomes that are causing swimmers itch on a particular lake?
Birds can be checked for avian schistosomes by hatching the miracidia from parasite eggs in the hosts’ feces. If hatch-year (young birds) that can’t fly are positive for avian schistosomes, then it must be concluded that they contacted the parasite on that specific lake. Not only can the bird species of dermatitis-producing parasite be isolated, but it is possible to determine the level of infection. This is done by weighing the fecal content and then counting the number of miracidia that hatch from one gram of feces. It is important not only to know what bird species serve(s) as hosts, but also the level of infection. To pinpoint the bird host even further, it is possible to take the miracidia that hatch from the feces and expose suitable lab-reared snails to determine if they get the infection. If the cycle can be reared in the laboratory, cercariae from the lab cultures can be compared to those that emerge from naturally-infected snails taken from areas on the lake where swimmer’s i
