Monday, 5 March 2012

The West Nile Virus Outbreak of 1999: A Compelling Argument for One Health


Dr. Tracey S. McNamara, DVM, DACVP (Professor of Pathology at Western University of Health Sciences College of Veterinary Medicine) presented a fascinating overview of the chronology of the response to the West Nile virus outbreak of 1999.  She highlighted the deficits present in our system of response, and brought to light the many yet-unanswered questions regarding how emerging zoonotic diseases are handled in the U.S.  A somewhat routine story of an emerging zoonotic disease outbreak took on new urgency and revealed conflicts when presented through the lens of the One Health concept.
A graduate of the New York State College of Veterinary Medicine at Cornell University, Dr. McNamara was working as the Bronx Zoo’s senior zoo pathologist at the time of the West Nile virus outbreak.  She currently serves in leading a collaborative effort with Russian colleagues on the “Human-Animal Interface” project as part of the Nuclear Threat Initiative’s Global Health and Biosecurity program in DC.

Dr. McNamara detailed how the initial discovery of dead crows on the zoo grounds coincided with an outbreak of what was thought to be St. Louis encephalitis (SLE) in New York City.  Necropsy of the affected birds revealed gross findings consistent with meningoencephalitis, and subsequent histopathology, virology, electron microscopy and immunohistochemistry confirmed that the birds were infected with the flavivirus West Nile virus.  Several facts pointed to the possibility that citizens of New York were not suffering from SLE.  Populations of sentinel birds in the zoo, who should have been affected were the culprit SLE, were thriving.  It became apparent to Dr. McNamara that perhaps WNV was affecting zoo avians and people in New York.  If so, this would be the first time the US would be facing a rapidly spreading zoonotic disease that had crossed species’ boundaries.

During the course of trying to work across agencies and confirm the zoonotic outbreak, Dr. McNamara faced tremendous obstacles in resources, available information, and more importantly, cooperation between human and veterinary medicine.  It required her persistent, assertive approach to finally establish the link and to reveal that indeed, WNV was the cause of both avian and human infections and illness.

Dr. McNamara’s recounting of the challenges she faced in establishing the cause of the outbreak revealed the inefficiencies, gaps, and vulnerabilities in facing a zoonotic disease outbreak.  Ten years later, no clear contingency plan exists, yet zoonoses are three times more likely to be emerging than non-zoonotic diseases.  The WNV outbreak is the perfect story to illustrate the need for a One Health approach.

The session concluded with several salient questions for which there are as of yet no clear answers.  The U.S. faces vulnerabilities to bioterrorism that can be met with the concept of interface between medical, veterinary, public health, and environmental agencies working together.  The need for the One Health approach is evident.  What are needed now are the practical and consistent applications of that approach.  This was an excellent presentation that illustrated that interdisciplinary cooperation is imperative.

Post authored by Jennifer S. Huff, RN
Graduate Student, UNC MPH Public Health Leadership Program

Up next (13 Mar):  
WaSH and One Health 
Jamie Bartram, PhD, Professor Environmental Sciences & Engineering at UNC
Microbial impacts of animal agriculture on water quality and human health risks
Mark Sobsey, MS, PhD, Professor, Department of Environmental Sciences and Engineering, Director, Environmental Microbiology Laboratory at UNC