Method for Testing Ointments and Fabrics to Determine Their Effectiveness as Barriers to Schistosome Cercariae

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  • Naval Medical Research Institute, National Naval Medical Center, Bethesda, Maryland
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Summary and Conclusions

Ointments and clothing samples can be given a general screening to determine their value as barriers in protecting man from infection by schistosome cercariae. The method depends upon the development of a rash with local inflammatory reaction at the site of cercarial penetration in mammalian skin and upon the count of these penetration sites about 24 hours after exposure of the skin test area to a counted number of cercariae. Test samples can be handled with relative ease and results obtained quickly.

This method of testing schistosome cercarial barriers appears to be an improvement over previously described technics because:

  1. a.The number of test animals is held to a minimum; test rabbits need not be sacrificed and may be used over and over again.
  2. b.There is no 4 to 6 weeks' period of delay between testing (i.e., time of host infection) and time of autopsy, as is necessary with other technics.
  3. c.There is no need for time-consuming examination of autopsied hosts to determine the presence or absence of adult worms.