92 
DR. FREDRICKSON: Dr. Walters? 
DR. WALTERS: Dr. Barkley, you mentioned statistics that have been 
kept on laboratory-acquired infections. I wonder if you would mention 
what the number of documented cases of laboratory-acquired infections has 
been for perhaps the past 30 years. 
DR. BARKLEY: As I pointed out, the late Dr. Sulkin and Dr. Robert 
Pike of the University of Texas have, for the last three decades been in- 
volved in collecting information from the literature and from personal 
contacts on the occurrences of laboratory-acquired infections. They have 
accumulated information on 3,921 cases; about 300 were reported earlier 
than 1925. The bulk of the 3,921 laboratory-acquired infections have been 
in the last three decades. 
It is of interest to note that the number of recorded infections is 
probably a very low figure — in fact, an extremely low figure. The num- 
bers do not include subclinical infections. They only include those 
infections brought to the attention of Sulkin and Pike. 
The other thing I would like to point out is that of the 3,921 cases 
over 900 have been involved in 35 micro-epidemics within laboratories. A 
micro-epidemic is one in which one exposure incident resulted in more than 
one infection among laboratory workers. Approximately 300 laboratory- 
acquired infections have been associated with the causation agent of Q 
fever, a very resistant organism. 
I would like to point out that even though we have had 35 micro- 
epidemics resulting in over 900 individual infections, there have only 
been 43 infections of persons not directly associated with the labora- 
tory. Twenty-nine of these infections were among personnel working in 
an animal rendering plant where hamsters infected with Q fever were sent. 
No laboratory-associated infections, however, have been reported to 
our knowledge that have been among persons who had no association with 
the laboratory activity. 
I think the other important thing to point out here is that the 
majority of these laboratory-acquired infections occurred in facilities 
where no biological safety controls were actually in effect. 
The experience in facilities with upgraded safety measures, however, 
indicate an encouraging record of few laboratory-acquired infections. 
Physical containment can, therefore, be effective in controlling such 
infections . 
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