California State Hygienic Laboratory, the forerunner of the current Microbial Diseases Laboratory (MDL), was established by legislative act on July 1, 1905. The laboratory came into existence amid a major public health crisis - the first plague epidemic of San Francisco. The primary laboratory at the Berkeley campus of the University of California soon expanded into three branch laboratories located in Los Angeles, Fresno and Sacramento. The testing of rabies and production of antiserum commenced as early as 1908 in the Pasteur Division of MDL, and a Division of Epidemiology soon followed in 1911.
The State Board of Public Health decided in 1912 to limit the State Laboratory’s direct testing to cities of less than 25,000 inhabitants, which led to the earliest established branch laboratories becoming local public health laboratories. This decision became an act in 1927, and led to a vast expansion of the local public health laboratories.
In close collaboration with the local laboratories, the State Hygienic Laboratory provided high quality reference testing for the control of communicable diseases such as diphtheria, typhoid, gonorrhea and tuberculosis. This partnership contributed to the foundation of a strong California public health infrastructure, which exists to this day.
Other major functions of the lab included production of antitoxins and antisera, sanitary microbiology, outbreak investigations, research and teaching. By 1945, the State Laboratory was performing approximately 10% of the total 1,297,774 tests reported by the California public health laboratories, with major emphasis on complex culture examinations, confirmatory tests, animal inoculations, serological techniques, and food and water analyses. Although some technology has evolved, the scope of reference testing at MDL has remained unchanged for more than a hundred years.
Currently, MDL is part of the California Department of Public Health (CDPH), Center for Infectious Diseases (CID), Division of Communicable Disease Control (DCDC). Located since 2003 on the Richmond Campus of the CDPH, the laboratory has four sections: Biologics; Mycobacteriology and Mycology; Enteric Diseases & Special Pathogens; and, Environmental Microbial Diseases. In addition to reference testing, MDL conducts applied research and provides instruction to Public Health Microbiologists and Postdoctoral Fellows. The laboratory has 60 staff members which include Laboratory Directors, Public Health Microbiologists, Research Scientists, Technicians and Fellows.