Procedures for preventing transmission of foot-and-mouth disease virus (O/TAW/97) by people

The Biosafety Research Road Map: The Search for Evidence to Support Practices in the Laboratory-Foot and Mouth Disease Virus

Introduction

Foot and mouth disease (FMD) is a highly contagious infection of cloven-hoofed animals. The Biosafety Research Road Map reviewed scientific literature regarding the foot and mouth disease virus (FMDV). This project aims to identify gaps in the data required to conduct evidence-based biorisk assessments, as described by Blacksell et al., and strengthen control measures appropriate for local and national laboratories.

Methods

A literature search was conducted to identify potential gaps in biosafety and focused on five main sections: the route of inoculation/modes of transmission, infectious dose, laboratory-acquired infections, containment releases, and disinfection and decontamination strategies.

Results

The available data regarding biosafety knowledge gaps and existing evidence have been collated. Some gaps include the need for more scientific data that identify the specific safety contribution of engineering controls, support requirements for showering out after in vitro laboratory work, and whether a 3- to 5-day quarantine period should be applied to individuals conducting in vitro versus in vivo work. Addressing these gaps will contribute to the remediation and improvement of biosafety and biosecurity systems when working with FMDV.

Technologies monitoring and improving biosecurity compliance in barn anterooms

People can act as mechanical vectors, and introduce and spread infectious diseases on farms. Preventive measures, such as changing boots and washing hands, need systematic implementation to manage this risk. Unfortunately, biosecurity compliance regarding biosecurity measures in barn anterooms has been shown to be generally low in all animal production systems. Indeed, the main challenge with biosecurity is maintaining compliance. The development of an effective on-farm biosecurity program requires several elements. These include farm and barn designs facilitating implementation of biosecurity measures; consistently communicating with all personnel and visitors informing them about threats and biosecurity; training programs for all farm personnel, explaining why biosecurity is effective in preventing infectious disease transmission, which measures are needed, and how to best implement them. All these components would be further optimized if automated monitoring systems were implemented with feedback mechanisms. Technologies are now available and are being adapted to the farm context to monitor biosecurity compliance. Two pilot projects using radio-frequency-identification-based (RFID) real-time continuous automated monitoring system quantifying hand sanitizing and boot compliance were conducted. The first one (MediHand Trace system) was a system designed to monitor and provide real-time feedback for handwashing in a hospital environment. It was functional for this task, although not sturdy enough for long-term use in a farm environment. The second system was a prototype designed for barns and with foot mats allowing the monitoring of footwear management as well as handwashing. These pilot studies have shown that real-time feedback helps improve compliance. However, the efficacy of the systems was very dependent on the physical set-up of the anteroom.

Epidemiological Characteristics of Foot-and-Mouth Disease in the Republic of Korea, 2014-2019

This study describes the epidemiological characteristics of six epidemics of foot-and-mouth disease (FMD) in the Republic of Korea between 2014 and 2019. A total of 223 outbreaks had been confirmed in 40 municipalities across nine provinces. Most farms with FMD (194, 87%) were located in three densely populated livestock areas (Chungcheongnam-do, Gyeonggi-do, and Chungcheongbuk-do). More cases of FMD were found in farms with more than 1,000 pigs or 50 cattle (risk ratios = 1.27 for pigs; 9.46 for Korean native cattle) and fattening pigs. In farms affected by FMD, the proportion of animals with vaccine antibodies was low (5%-50% for Korean native beef cattle farms with FMD in 2017 vs. 97.5% in the surveillance in 2016). Effective control of FMD can be achieved through strict biosecurity measures, proper vaccination, regionalized management, and instilling awareness of FMD prevention in farmers.

Biosecurity in pig farms: a review

The perception of the importance of animal health and its relationship with biosecurity has increased in recent years with the emergence and re-emergence of several diseases difficult to control. This is particularly evident in the case of pig farming as shown by the recent episodes of African swine fever or porcine epidemic diarrhoea. Moreover, a better biosecurity may help to improve productivity and may contribute to reducing the use of antibiotics. Biosecurity can be defined as the application of measures aimed to reduce the probability of the introduction (external biosecurity) and further spread of pathogens within the farm (internal biosecurity). Thus, the key idea is to avoid transmission, either between farms or within the farm. This implies knowledge of the epidemiology of the diseases to be avoided that is not always available, but since ways of transmission of pathogens are limited to a few, it is possible to implement effective actions even with some gaps in our knowledge on a given disease. For the effective design of a biosecurity program, veterinarians must know how diseases are transmitted, the risks and their importance, which mitigation measures are thought to be more effective and how to evaluate the biosecurity and its improvements. This review provides a source of information on external and internal biosecurity measures that reduce risks in swine production and the relationship between these measures and the epidemiology of the main diseases, as well as a description of some systems available for risk analysis and the assessment of biosecurity. Also, it reviews the factors affecting the successful application of a biosecurity plan in a pig farm.

Shifting to foot-and-mouth disease-free status without vaccination: Application of the PROMETHEE method to assist in the development of a foot-and-mouth national program in Uruguay

Foot-and-mouth disease (FMD) is highly contagious, and the introduction of FMD virus in countries free of the disease can result in large epidemics, similar to those observed in the United Kingdom, Japan, and Uruguay. Many countries or regions of South America are recognized as "FMD-free with vaccination" or "FMD-free without vaccination." Uruguay has been certified as FMD-free with vaccination, and the transition to the status of FMD-free without vaccination has been discussed among the stakeholders of the Ministry of Livestock Agriculture and Fisheries (MGAP in Spanish). This study illustrates how the Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) can identify and rank alternative actions to be used in the national FMD program in Uruguay. It uses multiple-criteria decision analysis (MCDA) to structure the problem comprehensively. This helps to identify critical issues and potential solutions when planning a national FMD program for a country with a disease-free without vaccination status. The analysis highlighted the following perspectives: i) the importance of communication strategies as the country changes to "FMD-free without vaccination" status, as well as potential challenges such as a lack of trust in government; ii) the importance of enhancing epidemiological capacity and data management to allocate resources better and provide feedback from the surveillance system; iii) the need to re-evaluate the animal health compensation strategy to stimulate biosecurity and disease reporting; and iv) the importance of assisting the backyard pig sector given the risks it carries and the complexity of dealing with because of its informality, the educational status of its owners, and the lack of formal assistance by veterinary services. The results suggests that the MCDA approach could be a useful tool for animal health agencies when planning a program to eliminate FMD (as well as other diseases) in a structured way because it helps to identify which alternatives would yield more effective results and it helps to address future challenges.

Network analysis of pig movements in Argentina: Identification of key farms in the spread of infectious diseases and their biosecurity levels

This study uses network analysis to evaluate how swine movements in Argentina could contribute to disease spread. Movement data for the 2014-2017 period were obtained from Argentina's online livestock traceability registry and categorized as follows: animals of high genetic value sent to other farms, animals to or from markets, animals sent to finisher operations and slaughterhouse. A network analysis was carried out considering the first three movement types. First, descriptive, centrality and cohesion measures were calculated for each movement type and year. Next, to determine whether networks had a small-world topology, these were compared with the results from random Erdös-Rényi network simulations. Then, the basic reproductive number (R₀ ) of the genetic network, the group of farms with higher potential for disease spread standing at the top of the production chain, was calculated to identify farms acting as super-spreaders. Finally, their external biosecurity scores were evaluated. The genetic network in Argentina presented a scale-free and small-world topology. Thus, we estimate that disease spread would be fast, preferably to highly connected nodes and with little chances of being contained. Throughout the study, 31 farms were identified as super-spreaders in the genetic network for all years, while other 55 were super-spreaders at least once, from an average of 1,613 farms per year. Interestingly, removal of less than 5% of higher degree and betweenness farms resulted in a >90% reduction of R₀ indicating that few farms have a key role in disease spread. When biosecurity scores of the most relevant super-spreaders were examined, it was evident that many were at risk of introducing and disseminating new pathogens across the whole of Argentina's pig production network. These results highlight the usefulness of establishing targeted surveillance and intervention programmes, emphasizing the need for better biosecurity scores in Argentinean swine production units, especially in super-spreader farms.

The Risk of Foot and Mouth Disease Transmission Posed by Public Access to the Countryside During an Outbreak

During the 2001 UK FMD outbreak, local authorities restricted rural access to try to prevent further disease spread by people and animals, which had major socio-economic consequences for rural communities. This study describes the results of qualitative veterinary risk assessments to assess the likelihood of different recreational activities causing new outbreaks of foot and mouth disease, as part of contingency planning for future outbreaks. For most activities, the likelihood of causing new outbreaks of foot and mouth disease is considered to vary from very low to medium depending on the control zone (which is based on distance to the nearest infected premises), assuming compliance with specified mitigation strategies. The likelihood of new outbreaks associated with hunting, shooting, stalking, and equestrian activities is considered to be greater. There are areas of significant uncertainty associated with data paucity, particularly regarding the likelihood of transmission via fomites. This study provides scientific evidence to underpin refinement of rural access management plans and inform decision-making in future disease outbreaks.

Biosecurity assessment of Argentinian pig farms

The pig industry is growing very fast in Argentina with an increasing need for replacement animals, feedstuff and transportation of animals. One of the main competitive advantages of the Argentinian pig industry is its being free of most major pig diseases. Within this context, applying measures aimed to reduce the risk of introduction and spread of pathogens is critical. The aim of the present study was to assess the biosecurity of Argentinian pig farms. Two types of farms were assessed: firstly, all official suppliers of high-genetic-value (n = 110) and secondly, a sample from commercial farms (n = 192). Data on the external and internal biosecurity practices applied on the farms was collected with a questionnaire. Data was analysed using a correspondence analysis and a hierarchical clustering analysis, which allowed identification of types of farms with regard to the biosecurity measures applied. Key variables characterizing the clusters were identified through an indicator value analysis. In addition, the external biosecurity of the farms was evaluated by using risk assessment tools with respect to the potential introduction of porcine epidemic diarrhoea virus. Results made evident three clusters: the first one which, amongst other measures, applied several barriers to prevent the entry of people, trucks and other vehicles, and could be considered as a group of high biosecurity, and the two other groups which applied a lower number of external and internal biosecurity measures. The results of the risk assessment showed that the routes with the highest risk of disease introduction were: replacement animals, vehicles transporting feed or animals, and visitors. The assessment of the external biosecurity showed that most Argentinian farms were not prepared for the contingency of a pathogen such as porcine epidemic diarrhoea virus. Special efforts should be made in official suppliers of high-genetic-value farms with poor biosecurity scores since they are at the top of the pig production chain and can be key for the spread of diseases.

The Effectiveness of a Foot and Mouth Disease Outbreak Control Programme in Thailand 2008⁻2015: Case Studies and Lessons Learned

Three Foot and Mouth Disease (FMD) outbreaks in northern Thailand that occurred during the implementation of the national FMD strategic plan in 2008⁻2015 are described to illustrate the lessons learned and to improve the prevention and control of future outbreaks. In 2008, during a FMD outbreak on a dairy farm, milk delivery was banned for 30 days. This was a part of movement management, a key strategy for FMD control in dairy farms in the area. In 2009, more than half the animals on a pig farm were affected by FMD. Animal quarantine and restricted animal movement played a key role in preventing the spread of FMD. In 2010, FMD infection was reported in a captive elephant. The suspected source of virus was a FMD-infected cow on the same premises. The infected elephant was moved to an elephant hospital that was located in a different province before the diagnosis was confirmed. FMD education was given to elephant veterinarians to promote FMD prevention and control strategies in this unique species. These three cases illustrate how differences in outbreak circumstances and species require the implementation of a variety of different FMD control and prevention measures. Control measures and responses should be customized in different outbreak situations.

Temporary carriage of bovine coronavirus and bovine respiratory syncytial virus by fomites and human nasal mucosa after exposure to infected calves

BACKGROUND

In order to prevent spread of the endemic pathogens bovine coronavirus (BCoV) and bovine respiratory syncytial virus (BRSV) between herds, knowledge of indirect transmission by personnel and fomites is fundamental. The aims of the study were to determine the duration of viral RNA carriage and the infectivity of viral particles on fomites and human nasal mucosa after exposure to BCoV and BRSV. During two animal infection experiments, swabs were collected from personnel (nasal mucosa) and their clothes, boots and equipment after contact with calves shedding either virus. Viral RNA was quantified by RT-qPCR or droplet digital RT-PCR (RT-ddPCR), and selected samples with high levels of viral RNA were tested by cell culture for infectivity.

RESULTS

For BCoV, 46% (n = 80) of the swabs from human nasal mucosa collected 30 min after exposure were positive by RT-qPCR. After two, four and six hours, 15%, 5% and 0% of the swabs were positive, respectively. Infective virions were not detected in mucosal swabs (n = 2). A high viral RNA load was detected on 97% (n = 44) of the fomites 24 h after exposure, and infective virions were detected in two of three swabs. For BRSV, 35% (n = 26) of the human nasal mucosa swabs collected 30 min after exposure, were positive by RT-ddPCR, but none were positive for infective virions. Of the fomites, 89% (n = 38) were positive for BRSV RNA 24 h after exposure, but all were negative for infective viruses.

CONCLUSIONS

The results indicate that human nasal mucosa can carry both BCoV and BRSV RNA after exposure to virus shedding calves, but the carriage seems short-lived and the transmission potential is likely limited. High viral loads on contaminates fomites 24 h after exposure to infected animals, and detection of infective BCoV, indicate that contaminated fomites represent a significant risk for indirect transmission between herds.

Systematic Epidemiological Investigations of Cases of Senecavirus A in US Swine Breeding Herds

Epidemiological investigations were conducted on a case series of six Senecavirus A (SVA)-affected breeding herds in the United States to determine potential routes of introduction and enhance the swine industry's knowledge of SVA's clinical presentation and spread. Each SVA-affected herd was evaluated using a standard form to ensure that all relevant data were collected. The form was used to guide a detailed discussion about the clinical presentation of SVA and risk events that occurred in the 4 weeks prior to the first observation of clinical signs with the herd veterinarian and farm personnel. Each event was then subjectively assigned a risk level of low, medium or high likelihood for SVA introduction by the investigation team. The clinical presentation of SVA varied by case. All SVA-affected herds (six of six) reported increases in pre-weaning mortality and sow anorexia. Vesicular lesions were observed in four of six herds, and mild-to-moderate neonatal diarrhoea was observed in three of six herds. No gross anatomic or histologic lesions were observed in neonatal pigs that tested positive for SVA via PCR. Multiple potential routes of introduction were identified. Events subjectively rated as high risk for SVA introduction were on-farm employee entry (six of six), carcass disposal (four of six), cull sow removal (three of six) and breeding replacement entry (two of six). Non-swine domestic animals, rodents, other visitors, repairs outside swine barns, feed delivery, weaned pig removal and semen entry were assigned a high risk level in one of six herds. Cases occurred in breeding herds of all sizes with variable biosecurity in both swine dense and swine sparse areas.

Risk assessment as a tool for improving external biosecurity at farm level

Background

Biosecurity routines at herd level may reduce the probability of introduction of disease into the herd, but some measures may be regarded as expensive and cumbersome for the farmers. Custom-made measures based on individual farm characteristics may aid in improving the actual application of on-farm biosecurity.

The aim of the study was to provide a tool for calculating the effects of different biosecurity measures and strategies on the individual farm level.

A simple model was developed to assess the risk of disease introduction and the need for biosecurity measures in individual farms. To illustrate the general applicability of the tool, it was applied to theoretical examples of Swedish cattle and pig farms and diseases endemic in those animal species in the EU, in two scenarios with different between-farm contact patterns.

Results

The model illustrated that the most important factors affecting the risk, and the effect of biosecurity measures such as quarantine routines and protective clothing, were the frequency of between-farm contacts and prevalence of the disease. The risk of introduction as well as the effect of biosecurity measures differed between farm types and disease transmission routes. Adapting contact patterns to mitigate a specific disease risk was as important as biosecurity measures for some farm types, but the largest effect was seen when combining biosecurity measures with more planned contact patterns.

Conclusions

The risk assessment model proved useful for illustrating the risk of introduction of endemic diseases and the mitigating effect of different biosecurity measures on farm level. Model outputs could be used to justify prioritisation of measures or adapting contact patterns. The theoretic exercise of adjusting model inputs and comparing outputs may help veterinary advisors to understand farm-specific risks and motivate farmers to improve biosecurity in their individual farm, as it can be tailored to each farmer’s needs and preferences.

Biosecurity on Finnish cattle, pig and sheep farms - results from a questionnaire

Biosecurity is important in order to prevent disease transmission between animals on farms as well as from farm to farm. Personal biosecurity routines such as hand washing and the use of protective clothing and footwear are measures that should be used at all farms. Other measures are for example related to purchasing new animals to the farm. A questionnaire-based survey was undertaken to study the frequency of use of different biosecurity measures on cattle, pig and sheep farms in Finland. Information about which biosecurity measures are in use is needed for contingency planning of emerging diseases or when combating endemic diseases. Knowledge about the level of biosecurity of a farm is also needed in order to assess if and where improvement is needed. Information regarding biosecurity levels may benefit future animal disease risk assessments. A total of 2242 farmers responded to the questionnaire resulting in a response rate of 45%. The implementation frequencies of different biosecurity measures are reported. The results revealed differences between species: large pig farms had a better biosecurity level than small cattle farms. There were also differences between production types such as dairy farming versus beef cattle farming, but these were not as remarkable. Sheep farming in Finland is sparse and the large number of hobby farmers keeps the biosecurity level low on sheep farms. This might represent a risk for the entire sheep farming industry. The Finnish farmers were satisfied with their on-farm biosecurity. Eighty percent of the farmers report that they were satisfied even though the biosecurity level was not particularly high. The implementation of biosecurity measures could be further improved. Even though the disease situation in Finland is good today, one must be prepared for possible epidemics of threatening diseases.

Some challenges to progressive control of foot and mouth disease in Pakistan--findings of a pilot survey

Pakistan is at an initial stage for progressive control of foot and mouth disease (FMD). Understanding the risk factors for introduction, spread and persistence of the infection is important to design an evidence-based disease control programme. A rapid appraisal method was adopted, and a convenient sample of twenty commercial dairy farmers was interviewed. The following were considered to contribute in secondary transmission of infection: (i) intermediaries and service providers [animal health workers, animal traders and transporters, raw milk collectors, persons who remove skin of dead animals], (ii) places where animals come in close contact [livestock markets, animal fairs, communal grazing pastures, routes in villages where livestock move, watering points, animal transport vehicles], (iii) use of bulls immediately after recovery from FMD infection, (iv) range land/desert livestock production, (v) small holder sheep and goat production, (vi) purchase of replacement stock and fodder from infected locations. This article reveals contacts within and between villages, some of which may act as routes of transmission of FMD. The study suggests the need for zoosanitary education of the livestock keepers.

Short-lived carriage of foot-and-mouth disease virus in human nasal cavities after exposure to infected animals

A quarantine period for potentially contaminated personnel can be used to reduce the risk of transfer of foot-and-mouth disease virus (FMDV) from infected to susceptible premises. This is set at 72 hours in the UK, on the basis of results from laboratory studies and field observations. Previous analysis of FMDV carriage within human nasal cavities has relied upon virus isolation by culture in susceptible cells. This study, involving 51 people, evaluated a PCR method, which detected viral genomic material within 35 nasal swabs taken from personnel after up to eight hours exposure to infected animals. Only one of 23 people who was PCR-positive immediately after exposure to FMDV-infected animals remained positive the following day, indicating a low risk of prolonged carriage of virus in the nasal cavities.