EuFMD

A MODEL EXPLORATION OF CARRIER TRANSMISSION SUFFICIENT FOR MAINTENANCE OF ENDEMIC FMD

There are many factors which might contribute to the persistence of FMD as an endemic disease in many regions. One such factor is persistently infected livestock – animals from whom virus can be isolated more than 28 days after infection, also known as carriers. Despite anecdotal evidence of transmission from carrier animals, and recent evidence that oropharyngeal fluid from such animals can transmit infection, experiment after experiment has consistently failed to demonstrate transmission via contact-challenge. It is clear that if carrier animals can infect naïve animals, the per-capita probability of such an event must be very low.

We investigate the required intensity of transmission from carrier animals to sustain transmission of FMD, and whether this minimum intensity can be consistent with the repeated failure to demonstrate transmission from carrier animals in many experimental settings. Using a realistic model of FMD transmission explicitly modelling transmission within and between farms, as well as real shipment records and farm locations from the Republic of Turkey, we simulate the spread of FMD with different intensities of carrier spread, as well as combinations of other relevant parameters, and measure how likely the persistence of FMD over the duration changes as these parameters vary.

The model finds that it is theoretically possible for carrier animals to contribute towards persistence even at very low transmission values, and that the average duration of the carrier state is the parameter with the greatest effect on FMD persistence, as well as the average duration of disease immunity. However, more work needs to be done to understand the dynamics of FMD spread with and without carrier animals.

G. Guyver-Fletcher1,
I. Keskin2, A. Bulut2, K. Shea3, M. Ferrari3, M. Huran3, X. Li3, C. Jewell4, E. Gorsich1, M. Tildesley1

1 SBIDER, The Zeeman Institute, The University of Warwick, Coventry, United Kingdom
2 Ministry of Agriculture and Forestry, Republic of Turkey
3 Penn State University, Pennsylvania, USA
4 CHICAS, Lancaster Medical School, Lancaster University, United Kingdom

EuFMD Open Session
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TRACKING LIVESTOCK MOVEMENTS TO UNDERSTAND THE PATTERNS AND RISKS OF FOOT-AND-MOUTH DISEASE SPREAD IN TRADITIONALLY MANAGED SYSTEMS IN EAST AFRICA

Introduction

Livestock are essential to food security and livelihoods in sub-Saharan Africa, but suffer from poor productivity due to infectious diseases such as foot-and-mouth disease (FMD). FMD is endemic in this part of Africa, and outbreaks are frequent, driven mostly by unrestricted livestock movements. To control endemic FMD, comprehensive information on the patterns of spread through herd contacts is needed. However, data on livestock movements across the landscape, and how and where contact occurs remain limited.

Materials and methods

We deployed Global Positioning System (GPS) collars on cattle in 52 different herds to understand fine-scale movements and between-herd contacts in rural areas of western Serengeti, Tanzania, representative of agropastoral systems in East Africa. We used the telemetry data to characterise the patterns of movements and identify locations of interactions between herds that suggest FMD flashpoints. In addition, we examined patterns of contact across a range of spatiotemporal scales, relevant to different FMD transmission scenarios.
Results
We observed that daily movement of cattle increased with herd size and rainfall. Herd contact rates were highest at large spatial and temporal scales. Furthermore, contact was greatest away from household locations, during low rainfall and close to dipping points. Generally, there were higher contacts proximal to resource areas such as grazing and water holes, but only for smaller spatiotemporal contact scales.
Discussion
We demonstrate how widespread movements could heighten the risk of endemic FMD spread. Given that risk is directly related to contact, the probability of FMD spreading between herds could be four times higher when virus survival in the environment increases from one to up to 24 hours. Our results point at times and locations of greatest FMD transmission potential and that could be targeted through tailored control strategies, for example when rainfall levels are low, and around dipping and water points.

D. Ekwem1,
2, T. Lembo1, J. Enright1 , J. Buza2, G. Shirima2, R. Reeve1, G. Hopcraft1, T. Morrison1

1Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Science, University of Glasgow, United Kingdom.
2Nelson Mandela African Institution of Science and Technology, School of Life Sciences and Bioengineering, Arusha, Tanzania.

EuFMD Open Session
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A MULTI-SPECIES CONTACT-NETWORK MODEL: BETWEEN-FARM DISEASE SPREADING AMONG BOVINE, SMALL RUMINANTS AND SWINE POPULATIONS.

Introduction

Many infectious diseases infect multiple species and persist through a combination of within- and between-species transmission dynamics and processes. Here, we explore the epidemiological impacts of host-specific disease spread dynamics, among farms raising multiple livestock species: cattle, buffalo, pigs, sheep and goat.

Materials and methods

We reconstructed multiscale stochastic susceptible-infected network-based transmission model for within-farm dynamics and between-farm animal movements. A wide range of introduction scenarios was simulated on the empirical network. To mimic an initial stage of an introduced foreign animal disease we generated 100 runs over available 2-year network starting with 1.000 infected farms. Infection was then started randomly in farms with only swine, only cattle, only small ruminants and final scenario it started in farms with all species. The model was used to simulate control actions based on the identification of farms mode likely to be infected by its contact network.

Results

The largest epidemic had 45% infected swine farms whiten the first six months of simulation. We found that epidemic sizes were governed by which species the index was seeded to. As expected, the swine contact network was the most prone to spread disease, with a simulated prevalence of over 60% at the end of second year of simulation, followed by small ruminants’ and cattle with prevalence over 20% and 10% respectively.

Discussion

The size of epidemics initiated in cattle and small ruminants generated a higher amount of infection into other single species farm holdings. This work highlights the relevance of other than cattle farms in the between-farm transmission of possible foreign animal disease, i.e., foot and mouth disease. These results may serve as basic data in the planning of national or regional to designing risk-based targeted surveillance strategies considering a multi-species approach.

1N. Cárdenas,
2A. Omar, 3F.P. Nunes Lopes, 2G. Machado

1 Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
2 Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.
3Secretary of Agriculture, Livestock and Agribusiness of State of Rio Grande do Sul (SEAPA-RS), Porto Alegre, Brazil.

EuFMD Open Session
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R. deJong - Epidemiological investigation of FMD outbreaks in a bear rescue center by European Commission for the Control of FMD

Geographic distribution of peste des petits ruminants (PPR)

Abstract

Peste des petits ruminants (PPR) is a highly pathogenic viral disease infecting principally sheep and goats, but also some wild artiodactyls, camelids and suids. This disease circulates in large parts of Africa, Asia and Middle-East. Despite global control efforts, PPR continues to emerge and re-emerge in new areas. Importantly, an outbreak in Mongolia in 2016-2017 resulted in high mortality in the endangered Saïga antelope, highlighting the impact PPR can have, not only on global economy and food security, but also on wildlife conservation. PPR also emerged in Georgia in 2016. Interestingly, it appears that this outbreak did not result from an introduction from a neighbouring country as originally suspected but originated from Africa possibly with infected animals brought by plane into Georgia. On-going PPR circulation in North Africa and Turkey represents potential routes of emergence into the European Union via uncontrolled movement of infected animals. The first and only incursion into EU took place in 2018 in Bulgaria at the border with Turkey. This outbreak was quickly detected through on-going disease surveillance programmes and rapidly controlled following EU directives. Symptoms were mild with low mortality, which was unexpected. Clearly, we still need to learn more about the epidemiology of the disease. Improvement and exchange of knowledge on the disease and its diagnostic are key for efficient actions (through international research and lab networks). Transboundary animal movement is the most likely route of PPR spread. Regional, locally adapted strategies are needed to control the disease efficiently.

Arnaud Bataille
CIRAD
EU reference laboratory (EURL) for PPR
OIE/FAO international reference laboratory for PPR
France

EuFMD Open session - OS20 -
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QUANTIFYING THE ROLE OF LIVESTOCK MOVEMENTS FOR THE TRANSMISSION OF RVF IN NORTHERN TANZANIA.

The buying and selling of livestock represents a substantial contribution to the income and livelihood of the people who husband them, however these movements also represent a risk of infectious disease transmission. While the health and commercial costs of disease means that there is incentive to control them, those affected by these costs are often not those most responsible for causing them. Thus market forces cannot be relied upon to restrict disease transmission, and policy-based interventions to prevent pathogen spread are necessary. Modern data-driven approaches to livestock management mean that in many higher income countries, data on livestock movements are collected routinely and stored digitally, and so they can readily be used to inform disease control efforts. However in Tanzania, as with many other LMICs, data on movement patterns must be generated. Here, I describe the collection and analysis of a substantial dataset generated from paper records, which is used to generate a ‘synthetic’ dataset that replicates key features of recorded patterns of movements to represent livestock movement patterns across northern Tanzania. A combination of network analysis and simulation is then used to determine key locations that can be targeted for control of many diseases including the important zoonosis, Rift Valley Fever (RVF). We show that targeting control efforts at locations that are critical because of either their role in the network of cattle movements or the inherent local risk of transmission can provide similar gains in control efficiency. While further investigations are necessary to corroborate these results, they suggest that multiple levers may be available to manage this and other livestock diseases. Efficient control of livestock diseases in areas with limited data and resources available is essential and here, by demonstrating the potential utility of livestock movement data in targeting interventions, this provides an argument for routine collection of such data. This will be especially important for ongoing assessment of risks as we face a future of increased uncertainty in living with environmental and land use change.

R.R. Kao,
G Chaters, W. de Glanville, L. Matthews, J. Nyarobi, E. Swai, S. Cleaveland, & P. Johnson.

EuFMD Open session
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Nadia, Marcello and Leah talk about training

P. Bastiaensen - Is African swine fever returning to Africa? by European Commission for the Control of FMD

Welcome to a new episode of our podcast

Drs Hullinger and Gaynor discuss the recent EuFMD activities in the area of Animal Health Emergency Preparedness for Foot-and-Mouth Disease (FMD) and and other Similar Transboudary Animal Diseases (FAST Diseases).

Dr. Pam Hullinger is a veterinary epidemiologist, with over 30 years’ experience in private and public practice at the California state, US National and International levels. Her expertise includes animal health emergency response preparedness, diagnostics, modeling, animal welfare and continuity of business planning. She has led programs in animal disease spread modeling, FMD vaccination strategy and diagnostic assay development for transboundary animal diseases. Her experience with exotic disease outbreaks includes foot-and-mouth disease and velogenic Newcastle disease. Most recently was the Director of the Large Animal Teaching Hospital and the California Animal Health and Food Safety Laboratory System at UC Davis.

Dr. Sally Gaynor worked as a veterinary risk manager for the Department of Agriculture in Ireland for 27 years. She has over 20 years’ experience in emergency preparedness for, and control of, transboundary animal diseases and was Head of the National Disease Control Centre. Her experience of exotic disease outbreaks includes foot-and-mouth disease, avian influenza, Newcastle disease and swine influenza. She has been working for EuFMD as an Emergency Preparedness Expert since September 2018.

Welcome to a new episode of our podcast

Simulation exercises are an excellent tool to test contingency plans and improve countries’ preparedness against exotic animal diseases. EuFMD supports the organization of simulation exercises, particularly in South Eastern European countries, but the recent pandemic represented a challenge for their planning and implementation. As a solution, a new way of delivering simulation exercises was outlined: Simulation exercises remotely assisted, using a crisis simulation tool. The pilot simulation exercise organized in this way took place on June 2020 in Montenegro.

Maria de la Puente Arévalo works in the EuFMD in coordinating training, simulation exercises and other activities aimed at improving preparedness of European countries against FAST diseases. She graduated at the Complutense University in Madrid and has an MSc in One Health with the University of Edinburgh. She worked for more than 10 years as an official veterinarian in veterinary public health and animal health in Spain as was involved in the European Commission initiative Better Training for Safer Food.

Goran Filipovic works in the EuFMD in planning and implementation of simulation exercises, networking and other activities aimed at improving preparedness of South East Europe region. He graduated at the University of Belgrade Before working in the EuFMD, he worked on various national and regional projects for development and implementation of animal health strategies for prevention, control and eradication of animal diseases.