January 29, 2004
Good afternoon. I am Dr. Paul Mead, Medical Epidemiologist with the Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases at the Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services. I will concentrate, as requested, on two main issues within my testimony: CDC funding for states to report Lyme disease and the surveillance case definition of Lyme disease.
Lyme disease is the most prevalent vector-borne infectious disease in the United States. It is one of the nationally notifiable diseases, with more than 23,000 cases reported to the CDC in 2002. If not diagnosed and treated in its early stages, Lyme disease can result in serious complications. Laboratory testing for Lyme disease has improved, but greater understanding is needed of its performance in clinical practice.
CDC's Lyme disease prevention and control activity is a science-based program of education, research, and service, which partners with the National Institutes of Health and other federal agencies, state and local health departments, and other non-federal organizations. CDC supports national surveillance, epidemiologic response, field and laboratory research, consultation, and educational activities through intramural initiatives. CDC also funds collaborative studies on community-based prevention methods, improved diagnosis and understanding of pathogenesis, tick ecology, and development and testing of new tools and methods for tick control.
CDC's budget for Lyme disease is allocated each year by Congress. CDC received $7.1 million for Lyme disease in FY 2003 and $7.4 million in 2002. CDC distributes the majority of these funds to states and universities in the form of cooperative agreements.
CDC has mapped the national distribution and risk for Lyme disease and has defined environments, activities, and behaviors that place people at high risk of infection. CDC has developed new and effective devices and methods for preventing infection and safely reducing vector ticks in the environment, such as insecticide-treated rodent bait boxes. CDC developed improved and standardized diagnostic tests for Lyme disease and provided physician standards for use of these tests. CDC's research programs have provided an understanding of the pathogenesis of infection with the Lyme disease bacterium, and of the transmission of the bacterium by ticks.
CDC Next Steps
Lyme disease and other emerging tick-borne infectious diseases are cause for increasing concern with regard to public health and safety in the outdoor environment. CDC's program for 2004 and beyond emphasizes the goal of working with Lyme disease endemic communities to develop an Integrated Pest Management (IPM) approach which includes a wide assortment of practical tick control strategies. IPM employs environmental management, biological and chemical control of ticks, and enhanced personal protection through tick avoidance and other measures to prevent Lyme disease.
Other areas of research include the development of natural forest products for use as environmentally acceptable alternatives in pest control, deer- and rodent-targeted methods of insecticide application, further efforts to predict Lyme disease risk on a national scale, and further understanding of host immune responses to infection with the Lyme disease bacterium. Continued education and implementation of improved laboratory tests for early and correct diagnosis and treatment will further the trend of reduced complications from Lyme disease. As mentioned by Dr. Baker, CDC works closely with the NIH on fundamental research related to immune responses and diagnostic development.
CDC Funding for Connecticut Lyme Disease Prevention
As previously mentioned, CDC distributes most of its Lyme disease funds to the states and universities via cooperative agreements. In accordance with federal rules and regulations, cooperative agreements are awarded competitively based on objective review of proposals submitted by state health departments and other applicants. In general, Lyme disease cooperative agreements are re-competed every 3 years.
For over a decade, the Connecticut Department of Public Health has competed successfully for CDC Lyme disease funding, with the amount of funding increasing from approximately $140,000 per year in 1991, to approximately $845,000 per year in fiscal year 2003. Connecticut universities have also competed successfully, receiving just under $490,000 in CDC cooperative agreement funds in fiscal year 2003. Overall, CDC provided approximately $1.4 million to institutions in Connecticut for Lyme and tickborne diseases in fiscal year 2003.
As a partner in the cooperative agreement process, CDC is responsible for assuring that the overall objectives of cooperative agreements are modified over time to reflect new information and changing public health goals. In general, the overall objectives of Lyme disease cooperative agreements have shifted over the last decade from counting cases to devising and testing methods for preventing infection. The Connecticut Department of Public Health's decision to discontinue mandatory laboratory reporting reflects this increased emphasis on prevention. This particular form of surveillance for Lyme disease is costly and relatively inefficient. Money spent on mandatory laboratory reporting decreases the amount of funds available for prevention efforts.
In 2002, after five years of mandatory laboratory surveillance, Connecticut had the highest incidence of reported Lyme disease of any state. This is precisely where the state ranked in 1997, the year before implementing mandatory laboratory surveillance. There is no question that Lyme disease is an important public health concern in Connecticut; the question is how to prevent it. It is towards this question that CDC cooperative agreements are focused.
Lyme Disease Case Definition and Clinical Diagnoses
A clinical diagnosis is made for the purpose of treating an individual patient and should consider the many details associated with that patient's illness. Surveillance case definitions are created for the purpose of standardization, not patient care; they exist so that health officials can reasonably compare the number and distribution of "cases" over space and time. Whereas physicians appropriately err on the side of over-diagnosis, thereby assuring they don't miss a case, surveillance case definitions appropriately err on the side of specificity, thereby assuring that they do not inadvertently capture illnesses due to other conditions.
As adopted by the Council of State and Territorial Epidemiologists, a case of Lyme disease is defined for national surveillance purposes as physician diagnosed erythema migrans > 5 cm in diameter or at least one objective manifestation of late Lyme disease (musculoskeletal, cardiovascular, or neurological) with laboratory confirmation of B. burgdorferi infection using a 2-tiered assay. Laboratory confirmation is considered critical for late stage Lyme disease because the symptoms mimic many other common conditions. Without firm objective evidence of B. burgdorferi infection, persons with other diseases would be counted erroneously as having Lyme disease.
No surveillance case definition is 100% accurate. There will always be some patients with Lyme disease whose illness does not meet the national surveillance case definition. For this reason, CDC has stated repeatedly that the surveillance case definition is not a substitute for sound clinical judgment. Given other compelling evidence, a physician may choose to treat a patient for Lyme disease when their condition does not meet the case definition.
In conclusion, addressing public health issues such as Lyme disease depends on a strong public health system and sustained and coordinated efforts of many individuals and organizations. CDC will continue to work with its partners to develop and implement community-wide strategies to prevent Lyme disease, including educational efforts, tick control efforts, and the development of improved diagnostic methods.
Last Revised: February 3, 2004