Investigating Infectious Organisms of Public Health Concern Associated with Wild Meat

Abstract

The wild meat trade poses a significant threat to public health as it facilitates the spillover of zoonotic pathogens through high-risk activities such as the hunting, butchering, trade, and consumption of wild animals. Despite the health risks and association with marking epidemics including SARS, Ebola, and COVID-19, the global wild meat trade continues to thrive. To summarize the evidence available, primary literature published between 2000 and 2022 was systematically and critically assessed for evidence of zoonotic pathogens or other infectious organisms detected in samples directly from wild meat, from animals hunted for wild meat, or from humans exposed through high-risk activities. Within the 97 articles analyzed, a total of 114 pathogen genera (15 viruses, 40 bacteria, 54 parasites, and 5 fungi) were detected in wild meat animals belonging to 168 vertebrate species including mammals, reptiles and birds sampled in 32 countries. In the context of wild meat specifically, infectious organisms were differentiated between those with zoonotic potential (32% of reported genera), ectoparasitic vectors (1%), and possible opportunistic or environmental contaminants. Thirteen viral, four bacterial, and one parasitic genera were also documented in humans participating in wild meat trade activities, supporting pathogen spillover potential. Most studies employed a targeted approach to evaluate the presence of (i.e., polymerase chain reaction (PCR); n = 65) or exposure to (i.e., ELISA; n = 19) a specific pathogen, while only one study employed broad-spectrum metabarcoding techniques. The diversity of infectious organisms associated with wild meat are highlighted through this review and could be used to guide policy development. However, the common use of a selected set of targeted detection assays likely biases the exploration of pathogen diversity, therefore potentially preventing the discovery of "disease x". The global health risk demonstrated should make the illegal wild meat trade a priority for law-enforcement agencies and future research.

Figure 1

PRISMA flowchart illustrating the search strategy and systematic screening process for articles published between 2000 and 2022. The search criteria identified 4,297 articles, which was then refined as illustrated to produce 97 English language full-text articles for analysis.

Figure 2

Distribution of peer-reviewed articles and doctoral theses published between 2000 and 2022 selected for review based on pre-determined inclusion and exclusion criteria. Each year is divided into the number of papers published per infectious organism type assessed (viral, bacterial, parasitic, or a combination of pathogens). The dates of key epidemic and pandemic events have been included above for reference.

Figure 3

Global distribution of research papers included within the review. The color gradient represents the number of studies which were either conducted in or obtained samples from those countries (key provided). Nine studies involved more than one country and have been counted for each. Studies where samples originated from another country but were tested on importation are highlighted, being Austria (n = 1), France (n = 2), and the United States of America (n = 1). We used QGIS 3.24 to develop the map [31], with free data sets for country boundaries and land borders from “Natural Earth” [32].

Figure 4

Pathogen identification in wild meat samples across the most frequently targeted and reported animal taxa (in relation to the number of pathogen genera identified). The columns represent the number and type of pathogens identified across all samples.

Figure 5

Heat map representing the proportion of positive cases reported for viral genera detected across wild meat samples of families within the orders Primates, Rodentia, Chiroptera, and Artiodactyla.

Figure 6

Heat map representing the proportion of positive cases reported for bacteria genera detected across wild meat samples of families within the orders Primates, Rodentia, Chiroptera, Artiodactyla, and Carnivora.

Figure 7

Heat map representing the proportion of positive cases reported for parasite genera detected across wild meat samples of families within the orders Primates, Rodentia, Chiroptera, Artiodactyla, and Carnivora. Cases of Bertiella and Enterobius in Cercopithecidae have been excluded as the number of positive samples was not disclosed. Armillifer, Ascaridia, Dermanyssus, Goniocotes, Metadavainea, and Spilopsyllus were not represented by these families.