Live pig markets in eastern Indonesia: Trader characteristics, biosecurity and implications for disease spread

Utilising abattoir sero-surveillance for high-impact and zoonotic pig diseases in Lao PDR

National disease surveillance systems are essential to a healthy pig industry but can be costly and logistically complex. In 2019, Lao People's Democratic Republic (Lao PDR) piloted an abattoir disease surveillance system to assess for the presence of high impact pig diseases (HIPDs) using serological methods. The Lao Department of Livestock and Fisheries (DLF) identified Classical Swine Fever (CSF), Porcine Respiratory and Reproductive Syndrome (PRRS) and Brucella suis as HIPDs of interest for sero-surveillance purposes. Porcine serum samples (n = 597) were collected from six Lao abattoirs in March to December of 2019. Serological enzyme-linked immunosorbent assay (ELISA) methods were chosen for their high-throughput and relatively low-costs. The true seroprevalence for CSF and PRRS seropositivity were 68.7%, 95% CI (64.8-72.3) and 39.5%, 95% CI (35.7-43.5), respectively. The results demonstrated no evidence of Brucella spp. seroconversion. Lao breed pigs were less likely to be CSF seropositive (P < 0.05), whilst pigs slaughtered at <1 year of age were less likely to be PRRS seropositive (P < 0.01). The testing methods could not differentiate between seropositivity gained from vaccine or natural infection, and investigators were unable to obtain the vaccine status of the slaughtered pigs from the abattoirs. These results demonstrate that adequate sample sizes are possible from abattoir sero-surveillance and lifetime health traceability is necessary to understand HIPDs in Lao PDR.

Live pig markets are hotspots for spread of African swine fever virus in Nigeria

Livestock trading through live animal markets are potential pathways for the introduction and spread of economically important pathogens like the African swine fever virus (ASFV) to new areas in several countries. Due to the high demand for live pigs in Nigeria both for restocking and slaughter, live pigs are sold at designated live pig markets (LPM) in the country. This involves movement of pigs over long distances. Despite, reports of ASF outbreaks following restocking of pigs bought from LPMs, there is paucity of information on the role of LPMs in the epidemiology of ASF. In this study, data and pig samples (whole blood, sera, tissue) were collected from 4 selected LPMs in Nigeria (Dawaki, Katsit, Numan & Pandam) between 2019 and 2020. Samples were analysed by polymerase chain reaction (PCR) and Enzyme-linked Immunosorbent Assay (ELISA). Four genes of ASFV positive samples were characterized to identify the circulating genotypes. Results revealed trade activities involving transportation of pigs from these selected markets to 42 major cities and towns in thirteen (13) States of Nigeria. PCR results revealed an overall ASF prevalence of 10.77% (66/613). ASFV was confirmed by PCR in all the selected LPMs with a prevalence rate of 3.13%-23.81%. The phylogeny revealed genotype I and serogroup 4 based on the p72 protein that encodes the B646L gene and the EP402R gene encoding the CD2V. While sequence analysis of CVR of B602L gene revealed 8 tetrameric repeats variants, six of which have never been reported in Nigeria. Analysis of sera samples recorded a seroprevalence of 6.9% (16/217) within the study period. Findings from this study show that LPM are hotspots and channels for transmission and continuous spread of ASFV in Nigeria. Therefore, for ASF to be controlled in Nigeria, disease surveillance and regulation at LPMs are critical. This article is protected by copyright. All rights reserved.

With or without a Vaccine-A Review of Complementary and Alternative Approaches to Managing African Swine Fever in Resource-Constrained Smallholder Settings

The spectacular recent spread of African swine fever (ASF) in Eastern Europe and Asia has been strongly associated, as it is in the endemic areas in Africa, with free-ranging pig populations and low-biosecurity backyard pig farming. Managing the disease in wild boar populations and in circumstances where the disease in domestic pigs is largely driven by poverty is particularly challenging and may remain so even in the presence of effective vaccines. The only option currently available to prevent ASF is strict biosecurity. Among small-scale pig farmers biosecurity measures are often considered unaffordable or impossible to implement. However, as outbreaks of ASF are also unaffordable, the adoption of basic biosecurity measures is imperative to achieve control and prevent losses. Biosecurity measures can be adapted to fit smallholder contexts, culture and costs. A longer-term approach that could prove valuable particularly for free-ranging pig populations would be exploitation of innate resistance to the virus, which is fully effective in wild African suids and has been observed in some domestic pig populations in areas of prolonged endemicity. We explore available options for preventing ASF in terms of feasibility, practicality and affordability among domestic pig populations that are at greatest risk of exposure to ASF.

Perceptions and practices among Zambian sheep and goat traders concerning small ruminant health and disease

Trade in animals and animal products is a key factor in the transmission of infectious diseases. Livestock traders play an important role in this process, yet there is little knowledge of traders’ perceptions of animal disease or their associated actions. The aim of this study was to investigate perceptions and practices of Zambian small ruminant traders with regard to sheep and goat health and disease. It also analysed how existing perceptions and practices might affect risks of disease transmission through trade. A case study was performed at the two largest small livestock markets in Zambia: the Lusaka market in the capital and the Kasumbalesa market near the border with the Democratic Republic of Congo. Semi-structured interviews with 47 traders performed in April-May and September 2018 represent the core material. Zambian small ruminant traders frequently trade animals that have clinical signs of disease, either because they appear unaware or indifferent to the associated risks, experience financial constraints or assign responsibility for disease prevention to other value chain actors. In their decision about whether or not to sell a visibly sick small ruminant, traders appear to consider whether the clinical sign is perceived as ‘natural’ or the result of an illness, whether the buyer is aware of the animal’s health condition, and whether the animal is sold for consumption or breeding purposes. Traders appear to regard the veterinary certificate required to transport small ruminants in Zambia as proof of health, placing the responsibility for potential disease in traded animals on the veterinary authorities. In their description of a model trader, taking good care of and being sensitive to customer needs was emphasized, indicating that an efficient way to encourage traders to change their behaviour is to influence customer demands. In contrast to the focus in previous studies on identifying and filling knowledge gaps, the present study show that lack of knowledge is not central to why traders engage in disease-transmitting behaviour. Greater awareness of other reasons for certain perceptions and practices could lead to the formulation of risk communication strategies and mitigation measures that are relevant for the local context, as well as alternative strategies for changing trader behaviour.

Simulation modeling of influenza transmission through backyard pig trade networks in a wildlife/livestock interface area

Influenza constitutes a challenge to animal and human health. It is a highly contagious disease with wildlife reservoirs and considered as endemic among swine populations. Pigs are crucial in the disease dynamics due to their capacity to generate new reassortant viruses. The risk of informal animal trade in the spread of zoonotic diseases is well recognized worldwide. Nevertheless, the contribution of the backyard pig trade network in the transmission of influenza in a wildlife/livestock interface area is unknown. This study provides the first simulation of influenza transmission based on backyard farm connections in Mexico. A susceptible-infectious-recovered (SIR) model was implemented using the Epimodel software package in R, and 260 backyard farms were considered as nodes. Three different scenarios of connectivity (low, medium, and high) mediated by trade were generated and compared. Our results suggest that half of the pig population were infected within 5 days in the high connectivity scenario and the number of infected farms was approximately 65-fold higher compared to the low connected one. The consequence of connectivity variations directly influenced both time and duration of influenza virus transmission. Therefore, high connectivity driven by informal trade constitutes a significant risk to animal health. Trade patterns of animal movements are complex. This approach emphasizes the importance of pig movements and spatial dynamics among backyard production, live animal markets, and wildlife.

Evaluation of the impact of live pig trade network, vaccination coverage and socio-economic factors in the classical swine fever eradication program in Peru

Classical swine fever (CSF) is a viral infectious disease of swine with significant economic impact in the affected countries due to the limitation of trade, culling of infected animals and production losses. In Latin America, CSF is endemic in several countries including Ecuador, Bolivia, Brazil and Peru. Since 2010, the National Veterinary Services of Peru have been working to better control and eradicate the disease with an intensive vaccination program. The aim of this study was to evaluate the effectiveness of the vaccination program and determine which factors are still contributing to the persistence of the disease in certain regions of Peru. We integrated the data from the vaccination campaign, the live pig movement network and other socioeconomic indicators into a multilevel logistic regression model to evaluate their association with CSF occurrence at district level. The results revealed that high vaccination coverage significantly reduces the risk of CSF occurrence (OR = 0.07), supporting the effectiveness of the vaccination program. Districts belonging to large and medium pig trade network communities (as identified with walktrap algorithm) had higher probability to CSF occurrence (OR = 2.83 and OR = 5.83, respectively). The human development index (HDI) and the presence of a slaughterhouse in the district was also significantly associated with an increased likelihood of CSF occurrence (OR = 1.52 and OR = 3.25, respectively). Districts receiving a high proportion of the movements from districts that were infected in the previous year were also at higher risk of CSF occurrence (OR = 3.30). These results should be useful to guide the prioritization of vaccination strategies and may help to design other intervention strategies (e.g., target education, movement restrictions, etc.) in high-risk areas to more rapidly advance in the eradication of CSF in Peru.

Analysis of pig trading networks and practices in Uganda

East Africa is undergoing rapid expansion of pig rearing, driven by increasing pork consumption. Introduction and expansion of pig production systems in this biodiverse landscape may create new risks, including zoonotic pathogen transmission. Historically, biosecurity measures have primarily been focused at farm level, ignoring the important function pig traders fulfill between farmers and consumers. This study interviewed pig traders operating at Uganda’s only registered pork abattoir to describe their characteristics, business practices, biosecurity practices, and pig health management and reporting practices. All the traders were male, and nearly all (90.5%) relied on pig trading as their primary source of income. Most of the pigs brought for processing at the slaughterhouse were purchased from smallholder farms (87.3%). In addition, there was a significant difference in the high price paid per kilogram at farm gate by region (P = 0.005). High prices paid at farm gate were associated with holiday periods (P < 0.001), harvest season (P < 0.001), and drought (P < 0.001). Traders preferred buying live pigs from male farmers (88.9%) because they were considered the final decision makers and owned the pigs being sold. All pig traders were aware of clinical signs indicating a pig was sick. This study has provided baseline information on pig trader practices in Uganda. Improvements in local pork slaughterhouses and markets will benefit not only pig traders in accessing consistent customers but also individual pig farmers by increasing their market access. Finally, given their role as a link between farmers and consumers, traders would benefit from targeted inclusion in disease control and prevention strategies.