Evaluation of a novel syndromic surveillance system for the detection of the 2007 melamine-related nephrotoxicosis foodborne outbreak in dogs and cats in the United States

Abstract

The 2007 nephrotoxicosis outbreak associated with melamine and cyanuric acid adulteration of pet foods in the United States sparked an urgent need for a nationwide companion animal surveillance program. In 2016, we introduced a syndromic surveillance system based on a novel epidemiological algorithm, the proportionate diagnostic outcome ratio (PDOR). The PDOR procedure was validated using simulated outbreaks of foodborne illness (i.e., aflatoxicosis and gastrointestinal illness) in dogs and cats. In this study, we further evaluated the PDOR procedure using the 2007 melamine-related outbreak of nephrotoxicosis. The performance of the PDOR procedure was assessed by the time to alert and positive predictive value (PPV). Electronic medical records of dogs and cats seen at networked primary care veterinary hospitals across the United States were retrieved from a centralized database. The data of four relevant syndromic components: elevated serum creatinine concentration, vomiting, anorexia, and lethargy from July 28, 2006 to May 31, 2007 were prospectively analyzed using the PDOR algorithm. The results showed that the alerts generated from the analysis of elevated serum creatinine concentration could have led to an early detection of this nephrotoxicosis foodborne outbreak and were well matched to the reported timeline of the outbreak. Additionally, we also observed variations in the performance of the PDOR procedure across age of animals and syndromic components, with the PPVs ranged from 0.61 to 1.0. Combined with the findings from previous evaluations using simulated outbreak scenarios, this study provided additional evidence that the PDOR procedure can be applied in syndromic surveillance to effectively and accurately detect various types of foodborne illness outbreaks in companion animals. However, the interpretations of and responses to alerts require an understanding of clinical veterinary medicine and relevant syndromic knowledge, and should not be based solely on quantitative measures.

Can North American animal poison control center call data provide early warning of outbreaks associated with contaminated pet food? Using the 2007 melamine pet food contamination incident as a case study

“…These findings suggest that the MCTS definition which included non-specific syndromic components associated with melamine-cyanuric acid toxicosis such as diarrhea, anorexia, and lethargy, among others, may have increased the sensitivity of the scans. These findings contrast with those recently reported by other researchers, as they found the sensitivity of detecting the melamine incident decreased when non-specific syndromic components were analyzed compared to specific components like elevated creatine [ 17 ]. This contrast may be due to differences in the data sources and methodologies used in the two studies.…”

“…This adjustment effect, whereby the cluster size decreases as the amount of information in the model used for covariate adjustment increases, has been noted by other researchers as well [ 12 , 21 ]. The onset of these clusters concurs with the timing of syndromic clusters previously identified by other researchers using alternative data sources and methodologies [ 17 ], as well as the timeline of the outbreak [ 8 ]. Consequently, the clusters identified could have been helpful in identifying there was an outbreak of serious renal failure which may have helped lead to the early detection of this pet food contamination incident.…”

“…These factors should be considered prior to syndrome development and choosing an appropriate statistical methodology for conducting syndromic surveillance using APCC call data. Furthermore, it would be worthwhile to explore additional methodologies for analyzing these syndromic data, such as stratification [ 17 ], multivariate surveillance [ 19 , 39 ], and parallel surveillance methods [ 39 ] in order to assess multiple syndromes or syndromic components at once.…”

“…Although it began as a method for the early detection of bioterrorism incidents in human populations [ 10 ], syndromic surveillance has been successfully applied in a veterinary medicine context for the surveillance of livestock populations over the past 20 years [ 4 , 11 – 13 ]. Recently, syndromic surveillance has been used in companion-animal populations to successfully identify both infectious and non-infectious disease outbreaks, such as accidental environmental releases of toxic chemicals [ 14 ], clusters of infectious disease [ 15 ], and foodborne outbreaks [ 16 , 17 ].…”