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in the Chemical laboratory Edited by NORMAN V. STEERE, School of Public Health, University of Minnesota, Minneapolis, Minn., 55455
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XIII.
Microbiological Hazards in the Laboratory -Part One-Control G. Briggs Phillips, U S . Army Biological Laboratories, Fort Detrick, Frederick, Maryland
Almost since microbiology began as a science, accidental infections resulting from laboratory manipnlation of pathogenic microorganisms were recognized and recorded. Lords Pastem finally disproved t,he theory of spontaneous generation in 1861, and in the 1870%began his studies with disease-producing organisms. Robert Koch solved the problem of growing pure hacterial crdtures in the laboratory in 1881, and in the following two years discovered the etiologic agents of tubercdosis aud elalera. The organisms producing typhoid fever were identified in 1880, and five years later, in 1x85, two cases of oecupntionally-acqldred typhoid fever werc recorded in the German Imperial Heakh Service. I n 1893 another case of labor&ry-acquired typhoid fever was recorded in Gernmny and a case of tetanus was reported in France. In 1903 the first recorded ease of blastomyoosis following an accident;d self-inoculation occurred. Tod.?y, more than 7 0 years later, the problem of aceidontally acquired laboratory disease still exists. I t is not a t all unususl t o sec reports of laboratory infections in the current medical literature. Moreover, thmogh the years the frequency of reports of lahoratory infections appears to have increased as the science of microbiology has expanded. Microbiological safety in its simplest form relates to the ~ r e c i s econtrol of the microbinl elemenis in any particular environment. Its application in laboratories where pathogenic cultures or infected animals are being med will help to prevent infections in laboratory workers. A second reason for microbialogical environmental control is to protect the validity of the experiment. I n the absence of suitable cont,rols, laboratory results can be confounded by accidental or unintentional transfer of infectious microorganisms fmm animal to animal or from test tube to test tube. A third reason far microbiological ellvironmental control is to protect man from infection by labarz&xy animals not known to be infeetad. Human infections may result from m y laboratory use of animals. For example, laborittory animals used by a, psychology department for behavioral Presented a t the Laboratory Safety Workshop, Eleventh National Conference on Campus Safety, Rutgem University, New Bntnswick, N. J., July 14, 1964.
studies can present a human infectious hazard if they carry an unrecognized disease and if microbiological environmental control is inadequate. Tuberculosis in monkeys could be an example of an unrecognized disease. This article is directed primarily toward controlling microbiologicd haas.rds in the infectious disease laboratory to prevent occupational infeetiom. We should realize, however, that other applicable areas exist. We shall begin by considering what is known about the frequency and severity of laboratory infections and what we might learn from these d a t s that will help in assessing om own laboratory programs. Next, we will review the known and probable cawes of laboratory infections. Then we will consider the available methods for prevention, dealing with five approaches to laboratory safety and giving some specific recommendations for each. Finallv. we will discuss the educational
G. Briggr Phillip5 is Arrirtont Direct01 of Industrial Heolth ond Safety 01 the United Stder Army Biological Lobora. torier, Fort Detrick. He hold3 o degree in bacteriology from the University w Maryland. For twenty years he ha: been associated with a research an< control program to discover, evaluate, ar control microbiologicoi hazards on< accvpotianal infection.. He has beer author of over thirty publicationr onc technic01 reports and is o member ol many proferrionoi groups dealing wiB public health problems. In 1959-1 96C he war oworded o Secretory of thr Army', Research and Study Fellowrhip.
Incidence and Severity of Laboratory Infections German physicians were the first to p u b lish collected eases of laboratory illnesses. In 1915 Kisskalt ( 1 ) summarized infarmation from 50 cases of laboratory-acquired typhoid fever that had occurred in Germany since 1895. I n 1929 he published a summary of 59 cases of typhoid fever and 24 other labaratory-acquired diseases occurring between the years 1915 and 1928 (2). I n the late 1930's, Draese ( 5 ) p u b lished the results of an investigation of 111 laboratory infections, with 9 fatalities, occurring in Germany between 1930 and 1937. However, Draese, in his survey, declined to list laboratory infection8 of Weil's disease (leptospirosis) and yellow fever because of their high frequency. Through the years, several hundred publications have mentioned approximately 6000 laboratory infections. The largest single collection of cases was that published in 1951 by Sulkin and Pike (4). This survey listed 1342 laboratory infections occurring in the U.S. during a 20year period. Inclnded were infections caused by 69 direrent disease agents, resulting in 39 deaths. Throngh a committee of the American Public Health Assocration, Sulkin has continued lo tabulate reported cases; the total number
of eases now stands a t 2348 r i t h 107 deaths ( 5 ) . While these reports and surveys illustrate that there can be a microh~ologicd safety problem in infeetious diseuse laboratories, they give little concrete inform*
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reported in the htersture, and it sometimes is difficult to prove whether or not a disease actually was acquired during laboratory work. An even more elusive factor is the occurrence of accidental infection in laboratory workers who do not show recognizable clinical symptoms. In spite of the difficulties of complete remrtine we can establish some usehil ln-
types of laboratories. Although these rates w r y from 0.10 to 50.0 infectmns per million man hours where infectious disease agents are usod,to an appreciable extent and where good Infection deteetmn and adequate reporting exists, an expected laboratury iniection frequency rate is between 1.0 and 5.0 per (Conhued a page AJ4)
Volume 42, Number
7, January 7965 / A43
Safety
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Table 1.
epidemic was mused by the improper use of a centrifuge that spread air-borne contamination throughwtt the h~~ilding. Estimated Frequency Rater for Laboratory Infections
Year
Infections per million man honrs
11144-195
