IJERD – International Journal of Environmental and Rural Development (2020) 11-1

Research article
erd

Risk Assessment of African Swine Fever Virus in Pork in
Phnom Penh, Cambodia
VOUCHSIM KONG*
Department of Agro-Industry, Ministry of Agriculture, Forestry and Fisheries, Phnom Penh,
Cambodia
Email: kongvouchsim@gmail.com

PHEA SUM
M’s Pig ACMC (Cambodia) Co., Ltd, Phnom Penh, Cambodia

PHEARY MOL
M’s Pig ACMC (Cambodia) Co., Ltd, Phnom Penh, Cambodia

KAROLIN CHAN
Faculty of Veterinary Medicine, Royal University of Agriculture, Phnom Penh, Cambodia

SOCHEATA RATHA
Faculty of Veterinary Medicine, Royal University of Agriculture, Phnom Penh, Cambodia

SEAVCHOU LAUT
Faculty of Veterinary Medicine, Royal University of Agriculture, Phnom Penh, Cambodia

VUTEY VENN
Department of Veterinary Paraclinical Science, Royal University of Agriculture, Phnom Penh,
Cambodia
Received 25 January 2020

Accepted 30 April 2020(*Corresponding Author)

Abstract African swine fever (ASF) is an acute infectious and deadly viral disease that
affects domestic and wild pigs of all breeds and ages. ASF virus (ASFV) can spread vastly
to non-infected pig population, but it cannot be transmitted from pigs to humans. In
Cambodia, first ASF outbreak was transmitted from bordering countries and reported in fiveprovinces. While estimated 70% of ASF widespread all over the country, local farmers
experienced a greater economic loss. Among the four components of risk analysis, the study
determines the risk assessment, and hazard identification plays a crucial step in risk
assessment. The objectives of this study aimed to detect the presence of ASFV in pork on
local markets through qualitative risk assessment approach and propose possible measurable
recommendations to prevent ASF outbreak. The study was conducted during the period of
ASF outbreak in August 2019, and the qualitative detection of ASFV was conducted on pork
tissue samples selected from wet markets and supermarkets in Phnom Penh. Sample
extractions were isolated from 30 pork tissue samples and detected virus by iiPCR. The
qualitative result on detection of ASF virus is confirmed by PCR technique. The ASFV isfound in pork tissue samples in wet markets and supermarkets. Of the 30 samples, 21 (70%)
were found positive with ASFV, 6 in 9 (20%) tissue samples from supermarkets and 15 in 21
tissue samples from wet markets (50%) confirmed the presence of ASFV. With this result, it
indicates that likelihood of the ASF virus transmission would be very likely to occur and the
spread of ASF virus in pork tissue samples in wet markets and supermarkets is significantly
prevalent, and the virus is likely to spread quickly. Scientifically, there is no vaccine toprevent ASF, and as recommended by FAO, the influenced policy-based implementation isrequired in place to minimize further production losses. The implementations must be
strengthened through strict farm biosecurity guideline and slaughter of infected pigs, strict
import regulation (border and movement control of live pigs) and heavy penalty to illegal
import of live pigs. Based on this result, it may contribute to bring consumers’ and relevantⒸ ISERD

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stakeholders’ awareness to reduce high risk through early detection of ASFV at theslaughterhouses and markets by risk assessment approach. Further studies on risk
management and risk communication to complete the risk analysis of ASFV in pork arehighly recommended.
Keywords African swine fever virus, risk assessment, pork, markets, Cambodia

INTRODUCTION
African swine fever (ASF) is an acute infectious and deadly viral disease that affects domestic andwild pigs of all breeds and ages, and caused by a DNA virus belonging to Asfarviridae family(Guberti et al., 2018). ASF virus (ASFV) can spread vastly to non-infected pig population, but it
cannot be transmitted from pigs to humans (FAO, 2008). Although humans are not susceptible to
ASF, its outbreak causes noticeable socio-economic consequences to infected countries (Bellini,
Rutili and Guberti, 2016). In Cambodia, first ASF outbreak transmitted from bordering countries wasreported in Ratanakiri province by the Ministry of Agriculture, Forestry and Fisheries, MAFF (FAO,2019). ASFV has continued its transmission and spread quickly to Tboung Khmum, Svay Rieng,
Takeo and Kandal provinces. While estimated 70% of ASF widespread all over the country, local
farmers in these five areas experienced a greater economic loss. Majority of small- and mediumscale pig farms stop to operate temporarily, and a small number of commercial farms are being
operated (Siem Reap PDAFF, 2019).
In such cases, risk analysis, the process composed of hazard identification, risk assessment, risk
management and risk communication, is required. FAO/WHO (2006) defined risk assessment as theterm that is generally used to describe the entire process of making a public health decision regarding
a specific drug or agent and it is the scientific evaluation of known or potential adverse effects
resulting from human exposure to food borne hazards. According to Venn et al. (2014) as cited in
the Codex Alimentarius Commission (CAC, 1999), risk assessment is defined as integrated elementsof the structure of risk analysis and to be based on the following steps as shown in Fig. 1 and Fig. 2.

Fig. 1 Structure of risk analysis (Venn et al., 2014 cited in CAC, 1999)

Fig. 2 Risk assessment (Venn et al., 2014 cited in CAC, 1999)Ⓒ ISERD

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ASFV can be transmitted and spread from infected pigs directly to uninfected populations. The
cause of transmission is associated with virus-containing matter (blood, faeces, urine or saliva from
infected pigs) that contact directly with brought-to-farm infected pork, farm inputs and in-farm usedmaterials (bedding, pig cage, feed, equipment, clothing and footwear, means of transportation(vehicles), studied by Thomson (1985). In the research of Mellor et al. (1987), it has shown that ASFV
can be airborne within a short distance, approximately less than 2 kilometers.
ASFV has a remarkable ability to survive for long periods in a protein environment, and therefore
meat from pigs slaughtered in the infective stages of ASF or die naturally of the disease provides agood source of virus. Pork slaughtered from infected pigs with ASF provides a favorable protein
environment for the virus to survive in the tissues for a long period of time. The virus is strongly
resistant to high temperatures. The studies of McKercher et al. (1978) and Plowright et al. (1994)
confirmed that fresh, frozen, processed, or preserved (salted and dried) pork may contain the infective
virus. As ASFV is transmitted in a closer distance, it may be possible to prevent the occurrences byapplying strict biosecurity rules and observation. While taking precautionary measures in use, it isnecessary to limit accesses for people/ farm workers/ visitors and vehicles to enter the areas or farms
where pigs are kept. This is also ensuring that the farm managers/ owners and veterinarians are
disinfected before entering the critical areas/ farms with protective clothing and footwear, and free frominadvertent feeding of leftovers and pork (Penrith and Vosloo, 2009).
OBJECTIVE
This study aims to detect the presence of ASF virus in pork in Cambodian markets through risk
assessment approach, and propose possible measurable recommendations to prevent ASF outbreak.
METHODOLOGY
The study was conducted during the period of ASF outbreak, and the qualitative detection of ASF
virus was conducted on pork tissue samples using PCR technique certified by OIE approval number
20130108 for registration of diagnostic kits (GeneReach Biotechnology Corp., 2019). The samples
were selected from 7 wet markets and 3 supermarkets in Phnom Penh in August 2019. Primary
information was gathered by interviewing the key informants of the city slaughterhouses and sellers
in both markets. The distribution of live pig movement and slaughtered pork was from smallholder
famers, middlemen and traders who source for pigs from the small-scale farms and neighboring
countries.
Sample extractions were isolated from 30 pork tissue samples and detected virus. The analysis
samples were evaluated based on the insulated isothermal PCR technique that automates sample lysis,
nucleic acid extraction and amplification and detection of the target sequences. Pork tissue samples
were pretreated by weighting 40 mg of each pork tissue sample and placing them into a clean 1.5 ml
microcentrifuge tube with 0.5 ml of Sample Storage Solution atc-lysis. The pork tissues were
homogenized in the grinder and spined the tube for 1 minute in mini-centrifuge before transferring
200 µl of supernatant to an Extraction Cartridge. Then, Transfer Cartridge was prepared by placing
one Premix and one Transfer Cartridge for each sample; labeling the sample ID and Premix ID on
the side of Transfer Cartridge; removing Transfer Cartridge Cap; turning the notched side of the
cartridge away, and snapping the Premix vial into well #3 of the Transfer Cartridge. The Extraction
Cartridge was prepared by placing one Extraction Cartridge (B) for each sample; removing theExtraction Cartridge from the aluminum pack, labeling the sample ID on the side of Extraction
Cartridge; slowly peeling off the aluminum film; turning notched side, and loading 200 µl of
homogenized sample to the sample well of the Extraction Cartridge. After the preparations ofTransfer Cartridge and Extraction Cartridge were completed, the Extraction lot number of theExtraction Cartridge was entered into the PCR; then the loaded Extraction Cartridge was place into
the selected slot before the Reagent lot number of the Premix Reagent was entered. The Transfer
Cartridge to the selected was loaded into the slot and the analysis were ready to run in the PCR.

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RESULTS AND DISCUSSION
The qualitative result on detection of ASF virus is confirmed by PCR technique. The ASFV is foundin pork tissue samples in wet markets and supermarkets. Of the 30 samples, 21 (70%) were foundpositive with ASFV, 6 in 9 (20%) tissue samples from supermarkets and 15 in 21 tissue samples
from wet markets (50%) confirmed the presence of ASFV (Table 1). With this result, it indicates thatlikelihood of the ASF virus transmission would be very likely to occur (OIE, 2010) and the spreadof ASF virus in pork tissue samples in wet markets and supermarkets is significantly prevalent.
Guberti et al. (2018 and 2019) confirmed that the virus is present in the meat of sick pigs and cansurvive for more than 3 months in the meat and offal, about one year in dry meat and fat, and morethan one year in the frozen meat.
Table 1 Percentage of sample detection
Sample detection
Supermarkets (9 tissue samples)
Wet markets (21 tissue samples)

Positive number (ratio%)
20% (6/9)
50% (15/21)

Negative number (ratio%)
10% (3/9)
20% (6/21)

Source: Results from pork tissue samples detection of ASFV confirmed by PCR technique

Based on this early detection of ASFV, risk assessment as scientific-based approach identifies
four components including hazard identification, hazard characterization, exposure assessment, andrisk characterization are described in Table 2.
Table 2 Risk Assessment of ASF virus
Components of Risk
Assessment
Component 1.
Hazard Identification
Component 2.
Hazard Characterization

Component 3.
Exposure Assessment

Component 4.
Risk Characterization

Identifications
African Swine Fever Virus (ASFV), is a DNA virus in the Asfarviridae
Family. The causative agent of the disease, the ASF virus (ASFV), is the only
member of the Asfaviridae family, genus Asfivirus.
- Human consequence: ASF virus cannot be transmitted from pigs to humans.
- Economic consequence: In Cambodia, first ASF outbreak was transmitted
from bordering countries and reported in April 2019 in five provinces.
While estimated 70% of ASF widespread all over the country, local farmers
estimated in greater losses. The pig price is increasing. Infected pigs’ weight
50kg loss approximately 90% of selling price, while pigs’ weight 80kg loss
about 45%. Majority of small- and medium-scale pig farms stop to operate
temporarily, and a small number of commercial farms are being operated.
Spread of the disease related vehicles and staff movements at the farms andoperation of kitchens inside the farms (bring-in infected pork/contaminatedfoodstuffs with ASF virus), and contamination of vehicles and staff
movements and carcass at the slaughterhouse.
Combining the results of the preceding three steps and advice for decision
making (to continue conducting the study on risk management).

Source: Results from pork tissue samples detection of ASFV confirmed by PCR technique

As shown in Fig. 3, a timely detection and identification of an incursion of initial event (Event is
NOT likely to occur) of infected pig in the farms can remove/ cull the sources of ASFV and break theroutes of risk outcomes in slaughterhouses and markets (NO RISK). However, the result indicates that
70% of samples were found positive with ASFV and the contaminated pork are distributed in the markets
that would be very likely to occur (RISK outcome of interest DOES Occur).
Economically, the sources of infected pigs may not be removed/ culled eventhough early
detection is positive in farms which are still slaughtered and distributed in the markets. It seems the
supply chain of pigs is less identical. There are a number of actors in the pig supply chain; in which,mostly buyers, middlemen and traders are those who source for pigs in the local villages. Sometimes
farmers may contact buyers, middlemen and traders directly to sell their pigs. The purchases areⒸ ISERD

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operated daily, and pigs are transported by motorcycles or trucks from farms directly to theslaughterhouses. The research studies conducted by Thomson (1985) and Thomson and Tustin(1994) confirmed that ASFV can be transmitted and spread from infected pigs directly to uninfected
populations. The transmission is associated with virus-containing matter (blood, faeces, urine orsaliva from infected pigs). The infected pigs may be in contact directly with brought-to-farm infected
meat, farm inputs and in-farm used materials such as bedding, pig cage, feed, equipment, clothing
and footwear, and other means of transportation (motorcycles and vehicles). Mellor et al. (1987)
noticed that ASFV can be airborne over in a short distance approximately less than 2 kilometers that
may give a higher chance for the virus to spread in the affected populations/areas.

Fig. 3 A scenario tree outlining the biological pathways leading to swine selected from aninfected herd, and being either accepted or rejected after it has been PCR tested
The pork is sold raw and distributed to local markets. Some semi-commercial farms havearranged the contracts with village famers and the farms will purchase the pigs when they reach acertain market weight (Mutua et al., 2011 and Levy et al, 2013). A main cause of concern linked tothe spread of AFS is a typical practice of buyers, middlemen and traders visit villages and households
regularly. Farmers may sell their infected pigs to the buyers and the spread of ASFV may get incontact with other pigs. After slaughter those infected pigs, ASFV can survive for long periods in a
protein environment, and meat from pigs slaughtered in the infective stages of ASF or that die
naturally of the disease provides a good source of virus and a favorable protein environment for thevirus to survive in the tissues for a long period of time (FAO, 2010; Plowright et al. 1994 and
McKercher et al. 1978). Bellini et al. (2016) emphasized on the improvement of efficiency of thedisease control measures by early detection of ASF that the infected pigs may be identified at thefarms/slaughterhouses/markets.
CONCLUSION
The results show that the spread of ASF virus in pork tissue samples in wet markets and supermarkets
in Phnom Penh is significantly prevalent, and the virus is more likely to spread quickly in Cambodia.
Scientifically, there is no vaccine to prevent ASF. Technically, influenced policy-based
implementation is necessary to address to minimize further production losses. The implementations
must be strengthened through strict farm biosecurity guideline and slaughter of infected pigs, strict
import regulation (border and movement control of live pigs) and heavy penalty to illegal import oflive pigs. Based on this result, it may contribute to bring consumers’ and relevant stakeholders’awareness to reduce high risk through early detection of ASFV at the slaughterhouses and marketsⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2020) 11-1

by risk assessment approach. Further studies on risk management and risk communication tocomplete the risk analysis of ASFV in pork are highly recommended.
ACKNOWLEDGEMENTS
The authors would like to express a sincere appreciation and thank to M’s Pig ACMC (Cambodia)
Co., Ltd for providing supports in conducting this study. The authors would like to extend theappreciation for the diligent, motivated and dedicated work done by research team, and theproofreader, Ms. Marianne Gudmundsdottir Ernst.
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