By Maggie Morris
A national surveillance network that uses the medical records of companion animals could help prepare for a wide variety of emerging disease threats to humans and animals, including avian influenza, according to veterinary scientists at Purdue University's School of Veterinary Medicine.
The National Companion Animal Surveillance Program was originally designed to alert people to potential anthrax or plague outbreaks. New findings on tests of the program are detailed in the current edition of Vector-Borne and Zoonotic Diseases, a medical journal that focuses on diseases transmitted to humans by vectors such as mosquitoes or directly from animals.
Larry Glickman, a professor of epidemiology in the School of Veterinary Medicine, designed the National Companion Animal Surveillance Program in collaboration with Banfield, The Pet Hospital, a nationwide chain of veterinary hospitals. Between 2002 and 2004, tests were conducted on more than 10 million pet records to determine how the database could be used to monitor disease outbreaks.
"We discovered we can use analytical techniques to target specific geographic areas where vaccines need to be developed," Glickman said. "This early warning will become critical to stop the spread of avian flu virus and other diseases that might affect humans. The quicker we can identify the problem in the more than 150 million dogs, cats or pet birds that live in approximately 40 percent of all households in the United States, the greater the probability we can contain a disease before it spreads to humans."
Authors of the research paper were Glickman; George E. Moore, Nita W. Glickman and Richard J. Caldanaro of Purdue's School of Veterinary Medicine; David Aucoin of VCA Antech; and Hugh B. Lewis of Banfield, The Pet Hospital.
Researchers collected data from 80,000 companion animals treated weekly at more than 500 Banfield hospitals in 44 states. Additional data included reports from VCA Antech Diagnostics, a nationwide network of laboratories used by more than 18,000 private veterinary practices.
Medical records were transferred to Purdue, where they were stored and converted for analysis with the help of COMSYS Information Technology Services, a consulting firm located in Houston.
Based on the data, researchers found:
-- A clear pattern of association between flea and tick infestation in pets compared to the incidence of Lyme disease in humans, with a two-month lag and peak rates occurring during warmer months. This information allows veterinarians to anticipate unusual occurrences of diseases that are transmitted from animals to humans and design treatment methods. Public health officials also could be alerted so they could provide timely information to the public and spray affected areas for ticks. In addition, specimens such as these can be used for profiling a broader variety of diseases that are potentially transmitted to humans by fleas and ticks, such as Rocky Mountain spotted fever.
-- A 3.3 percent increase in the number of positive tests from 2002 to 2004 for a disease called canine leptospirosis. Leptospirosis can be transmitted from dogs to humans. The disease is currently the leading cause of acute kidney failure in dogs and also can damage the liver. Most animals and humans recover from leptospirosis if it is diagnosed early and treated with antibiotics. This research will help develop early warning signs and aid in the development of vaccines that target emerging new strains of leptospirosis. The data also documents an increase in the disease over the past 10 years, probably related to increasing contact between dogs and wildlife such as raccoons, Glickman said.
-- A correlation between the number of cases of influenza-like illness in cats and similar symptoms in humans in the Washington, D.C., area where Banfield has numerous hospitals. This pattern suggested common environmental causes of influenza in cats and people. The finding illustrates the importance of the ability of Purdue researchers to track diseases by geographic area and to detect statistical clusters of events in companion animals that could signal the introduction of new viruses into the United States, such as avian influenza virus due to bird migration or bioterrorism.
"We wanted to show that these animals could be used as sentinels of infectious agents and perhaps predict the occurrence of diseases in humans," Glickman said. "The long-term goal is to partner with other providers of companion animal health care and animal laboratory data to create a comprehensive system that will be a national resource to further the practice of evidence-based veterinary medicine and veterinary public health. We think there is no comparable human-surveillance system in the country."
In ongoing work, the Purdue researchers are investigating ways to monitor cats for avian influenza. In collaboration with Banfield, they have developed an early-warning system for the occurrence of canine influenza that is caused by a virus that appears to have jumped recently from horses to dogs. If a dog comes to a Banfield clinic with a predetermined set of clinical signs, the computer screen flashes in the hospital and information appears that advises the practitioner what samples to collect from the dog for virus identification. A similar real-time surveillance system could be used to identify the avian influenza virus in pet birds or cats, Glickman said.
"The avian flu virus could be the 'black plague' of veterinary medicine, but we can be proactive through early detection and vaccine development," Glickman said. "A reporting system such as this for companion animals will allow us to educate veterinarians and help the public. It also will demonstrate what is possible in human medicine with development of a more centralized and coordinated healthcare delivery system."
Source: Purdue School of Veterinary Medicine