Wildlife Pathogens and Zoonotic Disease Risk Assessment in Vietnam: A Wildlife Trade Hotspot

Abstract

Vietnam is a wildlife trade hotspot presenting multiple high-risk interfaces for pathogen spillover from wildlife to humans. However, the zoonotic disease risk remains poorly characterized in the country and needs to be assessed to better inform policy dialog and legislative reforms. A literature review was conducted to create a pathogen inventory of terrestrial vertebrates in Vietnam. Additionally, data from an existing global database were used to estimate the number of zoonotic pathogens found in different families. The literature review yielded 87 eligible records. A total of 162 pathogen species, including 22 parasites, 48 bacteria, two fungi, eight protozoans, and 82 viruses, were recorded in Vietnam in 46 families of terrestrial vertebrates belonging to four classes and 18 orders. The highest number of pathogens was observed in Muridae (rats and mice), followed by Pythonidae (pythons) and Cercopithecidae (Old World monkeys). A total of 12 out of 29 priority zoonoses in Vietnam were reported in 27 terrestrial wildlife host families. Zoonotic pathogens were reported at 11 human-wildlife interfaces. Most detections of priority zoonotic pathogens were made in free-ranging animals as well as in wildlife farms and primate facilities. A risk assessment, based on the number of zoonotic pathogens found, suggested that facilities with a very high risk of zoonotic spillover include bushmeat markets in cities and town, wildlife farms, restaurants and rescue centers engaged in trading, housing and breeding birds belonging to the Columbidae, Phasianidae, Ardeidae families, and mammals belonging to the Cervidae, Suidae, Felidae, Ursidae, Mustelidae, Cercopithecidae, Muridae, and Sciuridae families. These supply chain nodes where wildlife families are in contact with human populations should be strictly regulated and monitored, with stricter biosecurity measures. Breeding of several species belonging to high-risk and medium-risk wildlife families together in the same captive facility should be banned to reduce the risk of pathogen-host jumps.

Figure 1

Schematic flow chart of the literature selection for the review.

Figure 2

Number of zoonotic and nonzoonotic bacteria and viruses reported globally (database from Shaw et al. [23]) and in Vietnam (pathogen inventory from the literature review) in each wildlife host family. Host families presented in the figure were those included in the Vietnam pathogen inventory and for which at least 10 pathogen species were recorded. Three additional families (Cervidae, Colubridae, and Crocodylidae) known to be commonly raised in wildlife farms in Vietnam [10] were added to the figure.

Figure 3

Wildlife host families of 12 priority zoonotic pathogens in Vietnam. The remaining 17 Vietnam priority zoonotic pathogens that are not included in the figure have not been identified in terrestrial vertebrate wildlife in Vietnam.

Figure 4

Number of Vietnam priority zoonotic pathogens (bacteria and viruses) hosted by each wildlife host family globally (data from Shaw et al. [23]).

Figure 5

Number of pathogens detected per wildlife host families at each human–wildlife interface along the wildlife value chain in Vietnam.

Figure 6

Interfaces where 12 priority zoonotic pathogens were reported in wildlife in Vietnam. The remaining 17 priority zoonotic pathogens that are not included in the figure have not been identified in terrestrial vertebrate wildlife in Vietnam.

Figure 7

Zoonotic disease risk assessment of traded wildlife taxa at various facilities and point of sales along the wildlife supply chain (very high risk = VH, high risk = H, medium risk = M, and low risk = L). TCM, Traditional Chinese Medicine.

Figure 8

Cumulative traded taxa risk (very high risk = VH, high risk = H, and medium risk = M) in wildlife farms (below the diagonal) and number of farms breeding each combination of wildlife families in Vietnam (<10 facilities = “–”, 10–24 facilities = “+”, 25–49 facilities = “++”, 50–99 facilities = “+++”, and >100 facilities = “++++”) (above the diagonal).