Summary

A study was made of 100 human diaphragms in Mexico City to determine the incidence and degree of infection with T. spiralis.

Direct microscopic examination of samples weighing 50 gm. or more revealed a very high incidence (15 per cent) of low grade infections. Twelve of the 15 positive cases showed less than 1 cyst per gm. of tissue, while 9 showed less than 1 cyst per 10 gm. of tissue.

Xenodiagnosis, using albino rats, was used to detect viability in the positive cases. This method is proposed as a means of detecting all cases having viable larvae in future survey work.