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.

Hsin-Yi Weng,Mark A.L Gaona,Philip H Kass

doi:10.7717/peerj.9093

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.

Highlights

In late February and early March 2007 complaints of pet cats developing acute renal failure unveiled a large-scale foodborne illness outbreak in dogs and cats in the United States (Puschner & Reimschuessel, 2011)
During the study period (N = 307 days), 4,895,123 veterinary medical records were processed by the Aberrant Diagnostic Outcome Repository in Epidemiology (ADORE) system using the proportionate diagnostic outcome ratio (PDOR) procedure, with the majority being canine patients (83%) and young adults less than 8 years old (83%)
We evaluated the performance of a novel companion animal syndromic surveillance system for the detection of the 2007 melamine-related nephrotoxicosis foodborne outbreak

Summary

Introduction

In late February and early March 2007 complaints of pet cats developing acute renal failure unveiled a large-scale foodborne illness outbreak in dogs and cats in the United States (Puschner & Reimschuessel, 2011). Further investigations confirmed that two chemicals, melamine and cyanuric acid, had been added to adulterate wheat gluten used in the manufacture of pet foods for fraudulently increasing the apparent protein content in those products (Dobson et al, 2008). Consumption of both melamine and cyanuric acid can form a large quantity of crystals in the lumens of renal tubules, which can cause extensive lesions in renal tubular epithelial cells and result in crystalluria, uroliths, and nephrotoxicosis (Puschner & Reimschuessel, 2011). The full extent of the pet deaths and illnesses caused by the chemical adulterant is unknown, one survey reported at least 424 confirmed cases (66% cats and 34% dogs) (Rumbeiha & Morrison, 2011)

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Conclusion