Disease Surveillance Enters the 21st Century

Lara C. Pullen, PhD

November 27, 2013

Contagious disease data have been reported by cities and states to the federal government at weekly intervals in the United States since 1888. Now those data are publicly available in a computerized format thanks to a project at the University of Pittsburgh.

Willem G. van Panhuis, MD, PhD, from the University of Pittsburgh in Pennsylvania, and colleagues published their description of the database in the November 27 issue of the New England Journal of Medicine. The database includes all weekly surveillance reports from US cities and states published between 1888 and 2011. It includes 87,950,807 reported individual cases, each localized in space and time, extracted from 6500 tables.

Public access to this volume and the granularity of the health data are extraordinary, according to the authors. Development of the database was supported by the Bill & Melinda Gates Foundation and the National Institutes of Health.

Its developers named it Project Tycho after Tycho Brahe, the Danish renaissance astronomer who compiled the largest collection of astronomy data of his time, all without the use of a telescope. The detailed astronomy data enabled Johannes Kepler to derive his 3 laws of planetary motion.

"Historical records are a precious, yet undervalued, resource. As Danish philosopher Soren Kierkegaard said, we live forward but understand backward," explained Donald S. Burke, MD, University of Pittsburgh Public Health dean and senior author of the article. "By 'rescuing' these historical disease data and combining them into a single, open-access, computable system, we now can better understand the devastating impact of epidemic diseases, and the remarkable value of vaccines in preventing illness and death."

For this article, the researchers performed detailed analyses of 8 vaccine-preventable diseases: smallpox, polio, measles, rubella, mumps, hepatitis A, diphtheria, and pertussis. The database reveals baseline patterns of these diseases before the development of vaccines as well as reductions in rates of these diseases after vaccine licensure.

The authors point out that there have been multiple resurgences of 4 contagious diseases (measles, rubella, mumps, and pertussis), despite continual vaccinations of the population. For example, although pertussis vaccines have been available since 1920, there was a pertussis outbreak in 2012, with 38,000 cases nationwide. There have also been measles, mumps, and rubella outbreaks as recently as post-1980.

The authors suggest these outbreaks reflect gaps in herd immunity.

"Our analysis shows how high-resolution spatiotemporal data can be effectively used to illustrate these trends at the national and local levels and to inform public opinion about the necessity of vaccination programs. Detailed spatiotemporal public health data have too often remained inaccessible and therefore underutilized. Lack of access to historical epidemiologic data constrains scientific understanding of the dynamics of disease transmission, hampers disease-control programs, and limits public health education programs," the authors write.

"The consolidation of all of the data into 1 point of access in unprecedented. The immunization community has always tracked the epidemiology of outbreaks, but this database will better equip the public health community to understand outbreak control and management. One of its biggest values will be its contribution to understanding what changes the epidemiology of infectious diseases and reasons why outbreaks may occur," said LitJen Tan, PhD, chief strategy officer at the Immunization Action Coalition in St. Paul, Minnesota.

Dr. Van Panhuis and Dr. Burke have disclosed no relevant financial relationships. Dr. Tan has received honoraria for expert consultation from Pfizer, Baxter, and Sanofi-Pasteur.

N Engl J Med. Published online November 27, 2013.

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