Pathologist and veterinarian Tracey McNamara talked at Los Alamos this week about current infectious disease surveillance methods for zoonotic pathogens. Photo by LeRoy N. Sanchez, Public Affairs
Seventy percent of known bio-threats are zoonotic, according to pathologist and veterinarian Tracey McNamara, who spoke Tuesday, regarding the United States' current infectious disease surveillance methods for zoonotic pathogens.
While the country is making significant in-roads in infectious disease surveillance, we have yet to achieve a truly integrated bio-surveillance system for the detection of zoonotic threats, McNamara said at a Director's Colloquium in the Physics Building Auditorium at Technical Area 3.
One national animal monitoring effort for infectious diseases is the National Animal Health Laboratory Network (NAHLN), headed by the Department of Agriculture. By March 15, the NAHLN will have messaging systems adopting the Health Level 7 standard for messaging, allowing veterinarians and zoos across the county to send information in a consistent format to the national database. However, as the NAHLN focuses primarily on infectious diseases in agricultural animals it is limited in extensibility and usefulness in tracking infectious pathogens in wildlife.
On the other hand, McNamara asserts the National West Nile Virus Surveillance Program, a joint Center for Disease Control (CDC) / Zoological Program established in 2001, offers the capabilities to track zoological pathogens in captive and free-ranging wildlife. She argues that the National West Nile Virus Surveillance offers the most affordable, reliable testing schedule for zoos and provides a novel, extensible data source for national surveillance of West Nile Virus and potentially other emerging infectious diseases.
Additionally, she added, "this cooperative program was the first to deal with the issue of confidentiality for the source of animal data and the animal itself."
The "zoo network," the diagnostics and database component of the surveillance program, is the only public heath database that includes real-time, updated information across all 50 states every 24 hours. The concept behind the system is tapping into existing resources and providing an accessible current depository of information.
It accepts sample submissions on multiple animals and multiple samples per animal, thus, distinguishing it from previous attempts at a national database. Further, the network allows animal history tracking and provides user-friendly and multi-purpose diagnostic information to determine syndromic, zoonotic threats. While it currently is being used for West Nile tracking only, the database has the capability to accommodate the reporting of other zoonotic pathogens.
Currently, the system is able to generate reports along with tables and graphs and includes GIS mapping. Beginning March 31, the database will have the capability to generated automated reports, will be accessible over the Web and will use advanced algorithms. Future plans include applying encryption advances to the zoo network that will provide data to designated users at the CDC and the Department of Homeland Security. There also are plans to expand the zoo network to include additional veterinary software applications, dxLabs, to maintain its real-time capabilities.
"CDC is happy with the way it works and wants to expand the network to include other zoonotic threats," said McNamara.
In her justification of the importance of information obtained and shared by zoological institutions, McNamara argued that zoos act as resources since they routinely look for zoonotic threats and emerging pathogens due to the dangers they pose to the zoos' capture collections.
As such, zoos often routinely submit samples for testing. "Working in a zoo for 18 years, I practiced preventive pathology. Looking for the threat of an introduced disease was part of my daily job," said McNamara.
In fact, during the West Nile outbreak of 1999, zoos offered a built-in epidemiological monitoring system since they contain susceptible species and a stationary population, present the opportunity for serial sampling, are located in both urban and rural areas across the country and exist in close proximity to humans. Additionally, pest species are routinely trapped on zoo grounds and confiscated smuggled animals are often sent to zoos.
"Diagnostics of these animals provides a window into the kind of pathogens we need to be looking for," she said.
McNamara also asserted that wildlife rehabilitators are good diagnostic sources that should be included in the national surveillance effort. Along these lines, the National Wildlife Rehabilitation Association is pursuing efforts to conduct syndromic surveillance.
Even in light of these information-sharing advancements, a main point of her talk was clear: despite the progress being made in the area zoonotic disease surveillance, the system in the United States is still weak.
First of all, McNamara maintained, most of the budgeted money for bio-surveillance is at the top in the human health stage once the zoological pathogen has already spread from animal to human. "The way we are currently structured works against early detection through cross-species analysis, she said, adding, "We wait until taxpayers are in the emergency room."
Second, the main focus of infectious disease in animals is still on the food animals of economic importance, such as cows and chickens, leaving an unmet need to detect zoonotic threats in wild animal sentinels and reservoirs.
Finally, she said that the disease surveillance that is taking place in free-ranging wildlife has vulnerabilities. These include insensitivity to individual losses, a "mother nature mentality" representing a high threshold for wildlife deaths, lack of index case location, and inconsistency in various states' regulations (e.g. a wildlife pathologist need not be trained in pathology in some states.).
In short, she argues that the U.S. needs to share information to develop a national baseline. McNamara shared her experience in the former Soviet Union, saying that the Soviet Anti-Plague System is "an active disease surveillance system that is agent based, not species-base, and provides baseline data as well as archives specimens." Its goal is the detection of zoonotic threats in reservoir species prior to the spill-over into the human population.
"If it makes sense in the former USSR, why doesn't it make sense here?" she asked.
It appears the CDC may agree with her conclusions. It is submitting a $10 million proposal to Congress for creation of communications infrastructure, connecting resources and regional diagnostic centers for the purpose of infectious disease surveillance of zoonotic pathogens.
"We are burning our diagnostic bridges everyday. It is an uphill battle," said McNamara. She hopes that the lessons learned from West Nile Virus will shape the future of infectious disease diagnostics and monitoring and continue to prompt advancements in information-sharing efforts like those proposed by the CDC.
| Lab has animal surveillance initiative Like McNamara, Babetta "Babs" L. Marrone of Molecular Microbiology and Immunology (B-1), along with collaborators Kirsten McCabe and Yulin Shou both also of B-1 and Jeanne Fair of Climate and Environmental Dynamics (EES-2), sees the significance of "using wildlife smartly as sentinels for detecting emergence of zoonotic disease in the human population." Their Laboratory Directed Research and Development Exploratory Research (LDRD-ER) project titled "Development of Avian Immune Response Tests for the Early Detection of West Nile Virus" proposes the development of modern immunological methods based on flow cytometry for the surveillance of immune response to West Nile Virus in the local free-range bird population. It further suggests that this technology be applied to understand the immunological basis for West Nile Virus susceptibility and resistance in different avian species. The project would build upon unique resources at the Lab including an established Avian Nestbox Network currently used as part of an ongoing Department of Energy program in environmental monitoring and risk reduction in combination with the technology for advanced flow cytometry applications resident in the National Institutes of Health funded National Flow Cytometry Resource. |