What is foot and mouth Disease?

In 2001 the UK fell party to an epidemic of Foot and Mouth Disease (FMD) which led to the slaughter of 6.5 million animals and a cost of £8 billion.1 But what have we learned from it, and what has been done to stop it from happening again?

Foot-and-mouth disease is a viral disease found in cloven hoofed animals such as sheep, goats, deer, water buffalo, pigs and cattle. It is present all over the world and has had a significant impact on agriculture for many decades. It is highly infectious and can be transmitted in a variety of ways which contribute to the likelihood of epidemics and uncontrolled outbreaks. Although not usually fatal, FMD can cause health issues in animals which recover, such as increased chance of still-born offspring and damage to heart tissue2, and causes significantly decreased milk production in cows.3 As such, this disease is of significant economic and animal welfare importance.

In the UK, FMD is a notifiable disease which means that if the disease is suspected or diagnosed, it must be immediately reported to the Animal and Plant Health Agency (APHA). This helps to keep track of any outbreaks and allows Defra to quickly take measures to prevent widespread infection.

What are the signs of foot and mouth disease?

The disease typically presents as a high fever which declines after a few days, and blisters which form inside the mouth and on the feet which can then lead to lameness. In sheep and pigs, blisters in the mouth are less common, and the most obvious sign of FMD is sudden-onset lameness which quickly spreads through the flock.4 For more in-depth information on how to spot FMD, including images of clinical presentations, go to Defra’s information sheet here.

There is currently no effective treatment for FMD, although antibiotics can be administered to treat any secondary infections which arise from blisters breaking. In much of the EU, where there is no endemic FMD, affected animals are usually culled immediately to prevent spread and culling is extended to unaffected animals which are deemed to be at high risk of infection.

How can foot and mouth disease be prevented?

There is a vaccine for FMD, which prevents clinical presentation of the disease and limits spread, but there are issues surrounding its use and the subsequent transport of vaccinated livestock. In areas of the world where FMD is endemic, the vaccine is often used to successfully prevent major outbreaks among populations, but where the disease is not present, usually control and prevention of infection take precedence over vaccination.

The best defence against FMD is strict biosecurity measures and monitoring of all known outbreaks. Prevention is better than cure and preventing movement of any infected animals, equipment or meat is very important in limiting FMD.

How did the 2001 UK foot and mouth outbreak occur?

The origin of the epidemic in the UK is known to be a pig finishing unit at Burnside Farm, Heddon on the Wall, Northumberland. FMD was confirmed on these premises on 23 February 2001, where it was revealed that the majority of pigs on the premises in were indeed infected with the disease – albeit at different stages of the infection. Due to the incubation period of the disease in pigs being 2-14 days, it is possible that pigs infected with FMD before the diagnosis were sent to the abattoir. It was concluded that FMD was introduced to the site not through other animals, people, equipment or vermin but in contaminated meat products unknowingly fed to the animals. 

Subsequent spread of the disease from Burnside Farm came from movement of infected pigs to an abattoir in Essex, and more importantly airborne spread directly from the infected pigs to sheep kept on a nearby farm: Prestwick Hall Farm, Ponteland. 16 sheep from this farm entered the marketing chain and were sold, infecting other sheep, people and vehicles and thereby spreading FMD across the country. The extreme virulence of the virus meant that it was easily transferred between populations of animals and quickly spread once introduced.

How did foot and mouth turn into an epidemic in 2001?

 There are believed to be a number of contributing factors that came together to provide an opportunity for the disease to spread silently.

Defra reports the following factors were to blame for the outbreak:

  • There were delays in the reporting of the disease in the pigs
  • Movement of infected sheep through markets prior to any cases being diagnosed spread the disease widely
  • The virus emerged when the climate provided favourable conditions, enabling it to survive well
  • The virus emerged at the time of year where sheep are sold and transported regularly, enabling wider spread
  • Absence of distinctive signs in sheep, in comparison with other livestock in which it may have been diagnosed sooner
  • Large sheep populations with reduced farm labour/contracted labour allowed the disease to infect whole flocks without notice
  • Sheep are gathered regularly for management such as shearing, treatment and housing in winter meaning the disease had more opportunity to spread

How was foot and mouth stopped in 2001?

The primary control measure of the disease in the 2001 outbreak was the widespread culling of animals. Any animals showing signs of the disease were immediately culled and healthy animals in the surrounding area which were considered high risk were also culled. While this did eventually get the disease under control, the cost was enormous, both in economic terms, and in animal welfare terms. Around 6.5 million animals were culled and while farmers were given government compensation, the mental and emotional effects were far-reaching and constituted significant social trauma.5

A complete ban on movement of any livestock animals in the UK was implemented, and very strict biosecurity measures were put in place when entering or leaving any agricultural premises. Many farming communities were put under strict movement bans and social events and gatherings were completely cancelled over fear of spreading the disease. Parks where there were deer populations were closed to visitors and trade of animals out of the UK was stopped.

There are many lessons that were learnt from this epidemic and there are measures in place today that are solely due to it, such at the 6 Day Standstill Rule (6DSS) which prevents animals from being rapidly sold from one farm to another and helps to limit disease spread. With the current coronavirus pandemic still ongoing, perhaps it is time to take a look back at previous disease epidemics at lessons learnt and what can be implemented from them.

References

1.         The 2001 Outbreak of Foot and Mouth Disease – National Audit Office (NAO) Report. National Audit Office https://www.nao.org.uk/report/the-2001-outbreak-of-foot-and-mouth-disease/.

2.         Stenfeldt, C., Pacheco, J. M., Borca, M. V., Rodriguez, L. L. & Arzt, J. Morphologic and phenotypic characteristics of myocarditis in two pigs infected by foot-and mouth disease virus strains of serotypes O or A. Acta Vet. Scand. 56, 42 (2014).

3.         Ferrari, G., Tasciotti, L., Khan, E. & Kiani, A. Foot-and-mouth disease and its effect on milk yield: an economic analysis on livestock holders in Pakistan. Transbound. Emerg. Dis. 61, e52-59 (2014).

4.         Foot and mouth disease: how to spot and report it. GOV.UK https://www.gov.uk/guidance/foot-and-mouth-disease.

5.         Mort, M., Convery, I., Baxter, J. & Bailey, C. Psychosocial effects of the 2001 UK foot and mouth disease epidemic in a rural population: qualitative diary based study. BMJ 331, 1234 (2005).