A recent study has found livestock meat—specifically pork—to be the most common meat source of foodborne illness outbreaks in China, historically. Various other trends were also revealed by the attribution analysis, which aimed to understand the epidemiological characteristics of foodborne disease outbreaks related to meat and meat products in China from 2002–2017.

Data for the study was collected from the National Foodborne Diseases Surveillance System, which had records of 2,815 outbreaks caused by foodborne diseases related to meat and meat products during the 15-year time period. In total, the foodborne illness outbreaks resulted in 52,122 illnesses, 25,361 hospitalizations, and 96 deaths.

The analysis revealed that the foodborne illness outbreaks had been largely seasonal, with 66.93 percent of outbreaks concentrated from May–September; August was the peak month. Additionally, China’s eastern coastal and southern regions experienced the largest number of foodborne illness outbreaks.

The food category most commonly associated with outbreaks was livestock meat, causing 28.67 percent of outbreaks. Livestock meat was followed by poultry meat at 21.31 percent, prefabricated meat products at 18.72 percent, and cooked meat products at 12.36 percent. Livestock meat was also associated with the largest number of illnesses, hospitalizations, and deaths, followed by prefabricated meat products.

Among livestock meat items, pork was the most common food item leading to outbreaks (13.96 percent), illnesses (14.23 percent), and hospitalizations (14.42 percent). Beef was the most common food item leading to deaths (16.67 percent).

The most common cause of foodborne illnesses from meat and meat products was bacteria, resulting in 51.94 percent of outbreaks, followed by chemical contaminants at 13.75 percent. Of all disease-causing contaminants, Salmonella caused the largest number of outbreaks (14.92 percent). Vibrio parahaemolyticus (8.53 percent) Staphylococcus aureus (7.32 percent), nitrite (7.14 percent), Bacillus cereus (5.54 percent), Escherichia coli (3.09 percent), and banned drugs (2.98 percent) followed. Clostridium botulinum (34.38 percent) was the most common cause of death, followed by nitrite (14.58 percent).

Salmonella and nitrite were the most common causes of livestock meat contamination. Salmonella (102 outbreaks), and V. parahaemolyticus was the most common contaminant of poultry meat. Salmonella, nitrite, V. parahaemolyticus, and S. aureus were the most common causes of contamination of prefabricated meat products. Salmonella and S. aureus were the most common contaminants in cooked meat products. Banned drugs were the most common cause of animal viscera or thyroid contamination.

The most common contributing factors associated with outbreaks were improper processing (27.89 percent), followed by “various contributing factors” (21.53 percent), improper storage (8.24 percent), and cross-contamination (7.99 percent). Various contributing factors were defined as two or more contributing factors involving handling food that causes food poisoning. Among the reported outbreaks regarding the location of food preparation, households were the most common location, resulting in 34.39 percent of outbreaks, followed by restaurants (24.37 percent) and canteens (15.20 percent).

Various contributing factors and improper processing were both found to have caused bacterial contamination of meat and meat products. Improper processing was the most significant contributing factor to nitrite poisoning. Pollution or deterioration of raw materials was the most important cause of foodborne illness related to meat and meat products due to banned drugs.

The study notes some limitations. First, before 2011, there was no mandatory reporting to the foodborne disease surveillance system, and there was a certain amount of underreporting. Additionally, unknown food categories and etiologic agents make up a large part of this study, so an accurate picture of outbreaks was limited.