LABORATORY SERVICES

Even though the role of pathogenic bacteria and viruses in human health was defined in the nineteenth century, the first public health laboratories in the United States were called chemical laboratories and only performed elementary analyses of milk, water, and other substances. The Minnesota Board of Health established the first public health chemical laboratory in 1873, and in 1881 the New York legislature established the first state chemical laboratory. By 1869, most of the larger cities in Massachusetts had health boards that were actively involved in the area of sanitary engineering. The state's public health laboratory, established in 1886, was intended primarily to perform chemical analysis, though it was called a "hygienic" laboratory. Michigan followed Massachusetts' lead, moving into the regulation of food and water, and in 1887, the Michigan State Laboratory of Hygiene was established, with Dr. Victor C. Vaughn as director.

Both the Massachusetts and Michigan state hygienic laboratories began working on the connection between the public water supply and typhoid fever. This was probably the first application of bacteriology to sanitary science in the United States. By 1890 a number of state and local laboratories were established, with many of them doing both chemical and bacterial analysis.

The nation's first diagnostic public health laboratory was the result of work by Drs. Hermann M. Biggs and T. Mitchell Prudden. In 1887, these two physicians were able to isolate Vibrio cholerae, the bacterium that causes cholera, from the feces of ill passengers on an immigrant ship anchored in New York City harbor, and they were anxious to promote their technique as a routine diagnostic measure. It was not until a cholera scare in 1892, however, that they were able to convince the city health department of the need to establish a laboratory to develop and use diagnostic methods. On September 9 of that year, the New York City Department of Health's Division of Pathology, Bacteriology, and Disinfection was created, with Dr. Biggs as the director.

Biggs soon had a second disease upon which to focus his attention. Cases of diphtheria peaked in the 1890s in New York City, and Biggs was ready with a bacteriological diagnostic technique. He used this technique to demonstrate that half the patients in the New York City diphtheria hospital had been misdiagnosed. Because of this high rate of misdiagnosis, he stressed that laboratory testing to confirm a diagnosis would be cheaper than disinfecting and quarantining the homes of every case of suspected diphtheria. The health board agreed, and the first official medical bacteriologist in the United States, Dr. William H. Park, was appointed. Meanwhile, Biggs continued the expansion of the laboratory's diagnostic capabilities. He began routine laboratory bacteriological testing on every suspected tuberculosis case, despite his colleagues' skepticism of its value. In 1895, Biggs added vaccine production to the laboratory. He and his assistant, Park, refined the methods for production of the smallpox vaccine, and of diphtheria and tetanus antitoxins.

The New York City public health laboratory became a model for other public health departments. Within a few years, the diagnostic public health laboratory had become an essential component of an effective health department.

HISTORICAL SCOPE

The laboratory added a new dimension to public health department activities. The ability to isolate and identify disease-producing organisms immeasurably strengthened the prevention and control role of the department. However, this new health department tool of diagnostic bacteriology was not readily accepted by the general medical profession. Duffy, in "The Sanitarians," quoted from an 1884 JAMA journal article on Robert Koch and the tuberculosis (TB) bacillus that concludes a "too ready acceptance of the bacillus doctrine" was likely to do more harm than good and that "neither phthisis nor any form of tuberculosis (was) contagious."

Biggs and his associates in New York City met strong resistance from physicians to the city's board of health requirement to report all cases of tuberculosis. The attitude of New York physicians was duplicated around the country as more and more health departments instituted this requirement. Through perseverance and laboratory expertise, health departments were eventually able to convince the public and physicians that tuberculosis was communicable and not an hereditary disease related to environmental conditions.

As the diagnostic expertise of the laboratories grew, the ability of the public health dpeartments to control disease was bolstered. The ability to culture disease-causing organisms from asymptomatic people led to recognition of the carrier state and a reexamination of isolation practice. Laboratory-supported disease control efforts resulted in significant reductions in disease mortality by the early twentieth century.

By mid-century, most of the laboratories had evolved in service provision to the same general scope provided today: testing support of the communicable disease programs, chemical and bacteriologic testing of drinking water, analysis of food and milk, and limited non-communicable disease testing. As continuing advances in technology enhanced the diagnostic capabilities of the laboratories, the public health department core functions of assessment, policy development, and assurance were significantly strengthened.

Development of federal public health laboratories was slower than at the state level, although the nucleus of what would evolve into the National Institutes of Health was established in 1887. In that year Joseph Kinyoun founded the Laboratory of Hygiene, a bacteriology research laboratory at the Marine Hospital on Staten Island. In 1891, this laboratory was moved to Washington, D.C., where it expanded into what became the National Institutes of Health (NIH) forty years later. The NIH laboratories still focus primarily on research and are not usually considered front line public health laboratories. The Centers for Disease Control and Prevention (CDC), which is the acknowledged apex of the public health laboratory system, was established even later than the NIH. In 1942 the Office of Malaria Control in War Areas (MCWA) was established. In 1946 the MCWA was converted to the Communicable Disease Center. It was renamed the Centers for Disease Control in 1980, and in 1992 became the Centers for Disease Control and Prevention. The CDC has since matured into a collective group of laboratories and programs that is dedicated to preserving the health and wellbeing of the public. The testing performed by CDC, in conjunction with local and state laboratories, has been essential to the provision of safe drinking water, an increased awareness of the importance of environmental health issues, and the decline of communicable diseases such as syphilis.

ROLE OF THE PUBLIC HEALTH LABORATORY

Initially, the role of the public health laboratory (PHL) was simply to serve any of the perceived laboratory needs of the various jurisdictions. Over time this role was defined more precisely, although still ambiguously, under general categories. The PHL became a recognized central part of the public health infrastructure and was charged with supporting this infrastructure in each of the three core public health functions—assessment, assurance, and policy development. Because PHLs differ dramatically in complexity, dependent largely on the population served, the test menus of the laboratories differ greatly. In general, all laboratories support the following core functions: testing information relevant to monitoring the environment; assessing the population's health status; investigating and controlling disease outbreaks; treating and controlling communicable diseases like tuberculosis, syphilis, gonorrhea, and chlamydia; acting as a reference laboratory for private sector laboratories; and assuring the safety of food and water. In addition, many PHLs have ongoing applied research programs directed toward improving the reliability and efficiency of testing, and identifying and controlling emerging problems.

PHL support for assessment and assurance functions are the most diverse. Laboratory testing to support assessment may involve specimens from people, animals, insects, fomites (inert vectors), and environmental sources. Examples of this type of activity are varied, but one of the most common is to support the investigation of disease outbreaks. It is the laboratory's role to isolate and identify the causative agent and to identify the source of the infection, which may be other individuals, insect or animal vectors, water, food, or dirt. For example, in a food poisoning incident associated with restaurant meals, the laboratory is pivotal in the determination of whether the incident is localized (caused by poor food handling procedures or infected staff in a specific restaurant) or widespread (caused by contaminated food distributed to many places locally or nationally).

Population surveillance studies for assessment of disease prevalence in a community also rely on testing and information provided by the PHL. Neonatal screening for metabolic disorders, immune status screening, screening for sexually transmitted diseases, and screening for chronic diseases are examples of this aspect of information gathering by PHLs.

Rabies, botulism, and plague are examples of rare but important diseases of public health significance that are not identified except in public health laboratories. Rabies is routinely identified by dissecting out specific portions of the brain of suspect animals to look for the characteristic lesions produced by the rabies virus. Rabies testing may be performed as routine surveillance of the wild animal population or as a necessary adjunct to contact between an individual and a suspect animal. Testing for Clostridium botulinum toxin (which causes botulism) in food or humans requires, at present, the use of animals. This requirement is the basis for the restriction of this assay to PHLs. Plague surveillance is routinely done by PHLs in areas where plague is endemic in the animal population. If antibodies to plague are found in an animal population that may have contact with humans, such as ground squirrels near a picnic area, the area is closed to the public until an eradication effort is successful.

Support of the PHL for the assurance function of public health is probably the most unrecognized and underappreciated facet of its role. Some of the testing cited under the assessment function has elements of assurance, such as the con- firmatory reference testing that is offered to all private laboratories without charge. Private sector laboratories having difficulty identifying a microorganism—confirming the true antibody status of a patient or defining the resistance pattern of Mycobacterium tuberculosis, for example—are able to request help from a PHL. But the most important role of assurance testing is to assure that community water supplies are safe to drink. In addition to testing drinking water for chemical and microbiological safety, recreational water is tested to insure the safety of swimmers and bathers.

Another assurance function, not readily apparent to the public, is the screening of food handlers in restaurants and other facilities. Food poisoning events trigger this function if an organism is suspected or identified that can be transmitted through contamination of food by a food handler. The food facility staff is screened for suspect pathogens by the PHL, and any individuals found to be infected are removed from the job until subsequent testing assures that they no longer are infected.

The facet of assurance that is most often thought of in connection with PHLs is the provision of certain testing services to the indigent population and to other individuals who might not otherwise be able to afford tests. This aspect of PHL testing varies from state to state depending upon local laboratory resources or the availability of specimen transport to the state laboratory.

Participation of PHLs in the third core function, policy development, is largely through consultation or regulatory services. PHL staff is involved in policy development that impacts research and technology needs as well as health issues such as HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome), sexually transmitted diseases, and tuberculosis. Policies to solve environmental problems are often developed primarily by PHL staff. Some state PHLs develop and implement regulations that govern all aspects of private clinical and local public laboratory operations within the state. This includes laboratory personnel and facility licensure requirements and environmental monitoring requirements.

In summation, the primary role of PHL is as a service unit providing timely information to facilitate the public health department's mission to protect the health of the community. To adequately perform this role, the laboratory must be functionally integrated within the health depart- ment's relevant programs so that the needs and requirements of these programs are met. The unbiased information and laboratory data provided by a PHL are necessary adjuncts to an effective public health department.

COST OF SERVICES

Health care funding continues to increase, but, according to Health and Human Services estimates, public health spending is only about 1 percent of the total, and the expenditure for PHLs is only 3 percent to 5 percent of the public health allocation. This demonstrates that federal, state, and county governments are making a very cost- effective investment in PHLs. The cost savings of population-based interventions based on PHL testing information is estimated to be analogous to the cost savings (ten dollars for every one dollar spent) of an effective immunization program. This estimate is derived from potential medical costs saved versus screening costs for population-based surveillance testing, including that done for rabies, lead poisoning, sexually transmitted diseases, environmental carcinogens and pathogens, and metabolic disorders in newborns.

LABORATORY STRUCTURE AND ORGANIZATION

Because of the wide variability in population between and within states, there is diversity in both the structure and testing services of the PHLs in the individual states. All fifty states and the District of Columbia operate their own PHLs, and some states have local laboratories, which may be autonomous or simply local extensions of the state PHL. The CDC functions primarily as a reference laboratory for the state PHLs, providing confirma- tory and esoteric testing services that the state laboratories do not have the resources to perform. The CDC also funds assessment and assurance studies at the local level to investigate issues of particular public health importance. The CDC is an integral part of the PHL system, and plays an important role in national disease surveillance.

Although the Food and Drug Administration (FDA) laboratories are public in the sense of being part of a government organization, they are not public health laboratories because they are not part of a public health department. Both the Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA) also impact PHL operations. Much of the environmental monitoring done by PHLs follows EPA guidelines, and USDA regulations may directly or indirectly play a role in PHL operations. The other federal agency that has recently assumed a major role in PHLs is the Health Care Financing Administration (HCFA), which is involved in the development and implementation of federal regulations that affect all diagnostic laboratories. These regulations are part of the Clinical Laboratory Improvement Amendments of 1988 (CLIA), which supersede all state regulations governing laboratories unless the state regulations are more stringent. PHLs that have state regulations governing them in addition to the federally mandated CLIA regulations are subject to inspections on a regular basis to determine if they are in compliance with these laws. The CLIA regulations impact all aspects of laboratory operations. One of the biggest changes for PHLs is the regulation for a laboratory director. All PHLs function in an organization led by a health officer, but the training and academic preparation requirements for the role of laboratory director have varied by jurisdiction. In several states, the laboratory director does not need to have a scientific background or an advanced degree; in others, an advanced degree in a scientific discipline is required. CLIA regulations stipulate that the laboratory director of each PHL must be a physician or a doctoral-level clinical scientist qualified by training, expertise, and experience in the areas of testing offered by the laboratory. In addition, physicians may qualify to direct a laboratory performing high complexity tests (PHLs perform high complexity tests) if they have two years of experience directing or supervising high complexity testing. The only exceptions to these requirements are under a grandfather clause that states that those individuals who are qualified or could have quali- fied as director before February 28, 1992, under federal regulations or state law are eligible to function as laboratory director.

State population needs and resources largely dictate the size and complexity of state PHLs in terms of staff and test menu. The Lewin Group's report Public Health Laboratories and Health System Change, commissioned in 1997 by the United States Department of Health and Human Services, gives figures that illustrate this diversity. According to this report, in fiscal year 1996 the Tennessee state PHL had 186 full-time staff members and a budget of $9.5 million, whereas the Florida state PHL had 354 full-time staff members and a budget of $21 million.

In addition to the state PHL, many states also have regional, county, or city PHLs that provide a quicker response network, but which may forward some samples to the central state laboratory for testing or confirmation of results. The regional laboratories may be extensions of the state PHL or autonomous PHLs funded by the local jurisdiction. For example, Tennessee has four regional state branch laboratories in addition to the central state laboratory located in Nashville. This state PHL organization provides testing services for eighty-nine rural health departments and six metropolitan health departments. One regional laboratory has only two staff members and performs microbiology tests exclusively. In contrast, California operates thirty-nine PHLs in addition to the state laboratory. All of the local laboratories are autonomous and all but three are county health department laboratories. In contrast to this extensive PHL network, other states, such as Oregon and Wyoming, operate only a central state PHL.

Another major difference among state PHLs is the extent to which their resources are utilized in testing primary patient specimens, doing reference testing, training laboratory personnel, monitoring the environment, doing applied research, and functioning as a regulatory agency. Some state laboratories devote a major portion of their resources to direct patient specimen testing; others do very little testing of primary patient specimens and concentrate on reference testing, applied re- search, and regulatory and epidemiological roles.

Overall, the public health laboratory infrastructure comprises a large number of basically diverse federal, state, and local laboratories that, under the guidance of the CDC, are beginning to function as a network in areas of national public health concern such as food safety and bioterrorism. Individually, however, state PHLs are the major link between national health initiatives and delivery at the local level, where laboratory information is mandatory for success. Despite the variability in resource focus and complexity, all state health department laboratories have a responsibility to support the core public health functions either directly or in coordination with local or regional PHLs.

CHALLENGES FACED BY PUBLIC HEALTH LABORATORIES

A medical laboratory test is defined as any examination of material derived from the human body for the purpose of providing information for the diagnosis, prevention, or treatment of any disease or impairment. There are two types of laboratories where medical testing is a primary activity: clinical laboratories—including hospital laboratories—and public health laboratories. Although both types of laboratories perform many of the same testing procedures, their primary functions are fundamentally different. Clinical laboratories assist clinicians only with individual patients, whereas public health laboratories support the health officer whose responsibility is the community. The clinical laboratory supports primary patient care; the public health laboratory supports programs designed to prevent and control communicable dis- ease and environmental pollution, and plays a key role in epidemiological investigations of disease outbreaks. Clinical laboratories perform testing on specimens from humans; PHLs perform testing on specimens from many different sources— human, animal, insect, environmental, and food.

These are the historical roles of the two types of laboratories and the basis for the establishment of PHLs over a century ago. But there is growing concern in the public health community that the understanding of the significance of the public health laboratory to the public health infrastructure is being lost because of changes in health care systems and a belief that infectious diseases are under control. Former surgeon general William Stewart articulated this belief in 1979 when he declared that it was time to "close the books on infectious diseases" and concentrate on kill- ers such as cancer. Unfortunately, the comfortable conclusion that infectious disease has been vanquished is incorrect. Microorganisms are displaying their ability to subvert our defenses in ways not predicted. New viruses, for which we have no treatment, have emerged; bacteria, once thought conquered with antibiotics, have developed multiple resistance patterns. The U.S. General Accounting Office issued a report in February 1999 that estimates some of the costs associated with infectious diseases. According to this report, there are approximately thirty-three million cases and nine thousand deaths every year from food-borne illnesses, with an associated estimated cost of twenty-two billion dollars per year. Over the past twenty years, international travel has increased threefold along with a substantial increase in the importation of fresh food. These two factors have allowed infectious diseases to spread rapidly across borders. In addition to the incorrect premise that infectious disease has been conquered, rapid changes in the health care environment have profoundly affected traditional services delivered by PHLs.

Until the early 1970s, PHLs were the leaders in microbiology technology. The CDC scientific re- search laboratories developed improved assays for various organisms and transferred the technology to the PHLs. In turn, the PHLs functioned as training centers for the private clinical laboratory staff. This function, in conjunction with their reference service ability, gave PHLs an elevated status in the community. This status began to erode as private companies entered the biological research and development market. No longer was CDC the leader in reagent and technology development. Biotechnology companies began emerging at a rapid pace as the potential market for improved diagnostic technology became apparent. These companies sell directly to private clinical laboratories, supplying any necessary training along with the new technology. PHLs are no longer the conduit. In addition, private clinical laboratories, because of the highly competitive marketplace in which they operate, have surpassed most PHLs in services and information infrastructure.

These changing dynamics of the laboratory services marketplace accelerated during the 1990s with the growth of managed care, consolidation of laboratories, shrinking of public resources, and the direct competition of clinical laboratories. While more sophisticated technology has raised testing costs, managed care organizations (MCOs) and other providers have demanded that laboratories lower their fees for service. This has served to intensify competition among laboratories and stimulated a quest for more efficient and faster service modes. In general the private laboratories that have survived this competitive pressure have decreased their costs through economies of scale, increased their capacity for quick turnaround of results, and developed better information handling. PHLs have been slow in responding to the need to change, partially because of the resource issues, but also because of bureaucratic inertia. The result is a continuing erosion of stature and a decreasing volume of testing, with a perceived loss in surveillance data for community protection.

FUTURE OF PUBLIC HEALTH LABORATORIES

Image, in the form of perceived importance, is the key to the survival of the public health laboratory system. PHLs must be understood and viewed by the public, by public officials, and by the private sector laboratory professionals as an invaluable resource that contributes in a unique way to the maintenance of health in the population. PHLs must be responsive to changing needs and once again become technological leaders of the laboratory community.

At present, the public health laboratory system is composed of autonomous laboratories linked at the state level, and linked at the federal level to CDC, but not linked to each other or to private diagnostic laboratories. The concept of forming a true national laboratory network, comprised of both private and public laboratories, originated in the late 1960s and is being expressed in a rudimentary way through bioterrorism initiatives and national surveillance for food-borne diseases, antimicrobial resistance patterns, and emerging infectious disease concerns. To continue the momentum to build a strong national network and to focus public awareness on the integral role of public health laboratories in such a system, the Association of Public Health Laboratories (APHL) is developing a strategic plan that will encompass elements of public relations as well as the objectives and steps involved in the development of a national laboratory system. This is a difficult and momentous undertaking, yet it is essential to the provision of health protection at the national as well as at the local level. A critical role for the public health laboratory is to provide the leader- ship and initiative to create this vital laboratory system.

Sydney M. Harvey

(see also: Assurance of Laboratory Testing Quality; Centers for Disease Control and Prevention; Clinical Laboratories Improvement Act; Laboratory Technician; Reference Laboratory; Research in Public Health Laboratories; Screening )

Bibliography

Association of Public Health Laboratories (1999). Core Functions and Capabilities of State Public Health Laboratories. Washington, DC: Author.

Cordts, J. R. (1995). "The Laboratory as a Model Public Health Function." CDC/NCID Focus (March).

Duffy, J. (1996). The Sanitarians: A History of American Public Health. Urbana: University of Illinois Press.

Getchell, J. P. (1996). "The Role of the Public Health Laboratory and the Definition of Public Health Laboratory Services." The Nation's Health (September):19–21.

Lewin Group (1997). Public Health Laboratories and Health System Change.

Skeels, M. R. (1995). "Public Health Laboratories Build Healthy Communities." Laboratory Medicine 26:588–592.

U.S. Senate Subcommittee on Public Health (1999). Emerging Infectious Diseases: Consensus on Needed Laboratory Capacity Could Strengthen Surveillance. Washington, DC: General Accounting Office.