Attn. John A. Kiernan
Dept. of Anatomy & Cell Biology
University of Western Ontario

Dear John,

Interestingly, every time the question of diastase digestion is aired on
Histonet, the question of  whether to spit or not to spit also comes up.
You expressed doubt about the dangers of using saliva on sections in the
laboratory; so allow me therefore to relate the story of  an incident which
occured in our Department several years ago:

A post-graduate research worker, from a country where tuberculosis is
endemic, was working in our department and part of the procedure that he
was doing required diastase digestion to be carried out. He, of course, as
you will have suspected, was using his own saliva for the purpose. He was
subsequently found to be infected with TB, and his co-worker was infected
by him also.

Following this event we have never allowed the use of saliva for diastase
digestion as a laboratory technique.

Regards

John Difford
Department of Histopathology
Royal Free Hospital
London
England, UK.