An investigation points the finger at a drainage problem as the cause of breaches of biosecurity which lead to the August Foot & Mouth Disease outbreak in England. The investigation was carried out by the Health and Safety Executive (HSE). Leaking pipes were detected at Pirbright, Surrey, which most likely allowed the virus to seep through and make its way to two neighboring farms after being carried along the surface as a result of rains; as workers had been renovating the site at the time their vehicles probably became contaminated and carried the virus further.

Geoffrey Podger, HSE Chief Executive said

“During our investigation we established that it was possible for the live virus strain – O1BFS – to enter the site effluent drainage system. We judged it likely that waste water containing the live virus, having entered the drainage pipework, then leaked out and contaminated the surrounding soil. This conclusion is supported by evidence of long term damage and leakage, including cracked pipes, tree roots breaching pipework, and unsealed manholes. We also believe that excessive rainfall in July may have increased the potential for virus release from the drain.”

“Our report shows that during the period of our investigation both human and vehicle movements at Pirbright were not adequately controlled. We conclude that failure to keep complete records was not in line with accepted practice and represents a breach in biosecurity at the site. In particular, vehicles associated with ongoing construction work had relatively unrestricted access to the site. In our opinion, these construction activities – very near to the effluent drainage system – are likely to have caused disturbance and movement of soil in a way that contaminated some of the vehicles with the live virus. We established that some of the vehicles, probably contaminated, drove from the site along a road that passes the first infected farm. We conclude therefore that this combination of events is the likely link between the release of the live virus from Pirbright and the first outbreak of FMD.”

“We have drawn our concerns about the breaches of biosecurity, together with a number of recommendations, to the attention of the Pirbright site regulator – Defra – so that they can be rectified.”

The HSE and Defra (Department for Environment, Food and Rural Affairs) issued a joint safety alert to organizations which carry out work on pathogens in hazard groups 3 & 4, reminding them of the mandatory measures to safeguard primary and secondary containment.

Geoffrey Podger stressed that the safety alert is to draw employers’ attention to issues that have arisen as a result of the investigation – the message needs to be reiterated more vigorously and action must be taken accordingly. He added that these issues already form part of the basis on which such places are allowed to function; the alert is simply an urgent reminder to operators of their responsibilities.

Podger reminded operators that both HSE and Defra will be looking at these issues meticulously when they carry out their regulatory inspections – with special attention being paid to the handling of group 4 pathogens.

The Pirbright site consists of three organizations – the Institute for Animal Health (IAH), Merial Animal Health Ltd (Merial) and Stabilitech Ltd (Stabilitech) – which worked at different levels of the O1BFS virus strain that caused Foot and Mouth Disease (FMD) in the first sickened herd in Surrey. Tests indicate that this strain most likely originated from the Pirbright site. As the three organizations worked with slightly varying types of the strain it is not possible to pinpoint the origin to any of them, the HSE Final Report states.

Regarding other issues, the HSE Final Report states there was:

— No evidence of a breakdown of containment systems for solid waste disposal at Pirbright
— No evidence of a biosecurity failure that may have resulted in the virus spreading to the atmosphere
— No evidence of foul play – biosecurity breaches caused by malicious intent of staff

Geoffrey Podger said the investigation had been exhaustive, comprehensive and complex – and was carried out within four weeks.

— Click here to read the report (PDF)

What is Foot and Mouth Disease (FMD)?

FMD is an infectious disease which sickens cloven-hoofed animals, especially cattle, sheep, pigs, goats and deer. The disease is serious for animal health and the economic welfare of the farming (livestock) industry. Even though FMD is not typically fatal for adult animals, its consequences on loss of output can be dreadful. FMD can cause milk yields to plummet and animals frequently become lame. FMD can be deadly and on a large scale for young animals.

The after-effects of FMD are serious. Affected animals lose condition and are particularly at risk of bacterial infections. A dairy cow is much more prone to suffer from chronic mastitis, which permanently reduces the value of the cow. Animals which recover from FMD are much more likely to be infertile.

FMD is Caused by a Virus

FMD is caused by a virus of which there are 7 main types. These types can only be differentiated in the laboratory, as their symptoms are identical – fever, followed by blisters (vesicles) mainly in the mouth and feet.

The seven main virus types are: O, A, C, SAT.1, SAT.2, SAT.3 and Asia 1 – each type has subtypes. The average incubation period is between three to eight days – it has been known to be shorter, and as long as 14 days. The UK 2001 outbreak was the pan-Asiatic O type.

An animal that recovers from one virus type is not protected against infection from any of the other types.

How does Foot and Mouth Spread?

Enormous numbers of the virus are present in the fluid of the blisters, and to a certain extent in saliva, milk and dung. Any objects that come into contact with the blister fluids are a serious danger to other healthy animals. At its peak, FMD is present in the blood.

Before symptoms begin animals start excreting the virus. Pig’s dung can be especially contaminated.

Under favorable conditions, the disease can spread through the air for a considerable distance.

Animals become infected either as a result of direct contact with a sick animal or by contact with foodstuffs, dead carcasses, or touching anything a sick animals has touched.

With intensive farming these days animals are transported long distances and rapidly. This movement of animals and vehicles can accelerate the speed and distance of FMD spread. Even the roads themselves can become contaminated, increasing the risk that other vehicles pick them up.

How Widespread is Foot and Mouth Disease?

FMD is endemic in many parts of Asia, South America and Africa. In 2001 the UK, Eire (Ireland), France and the Netherlands had outbreaks of FMD.

Can Humans Get FMD?

According to the UK Department of Health, human infection of FMD is extremely rare. The only recorded human case in the UK was in 1966 – symptoms were similar to influenza (flu), plus some blisters and were fairly mild. There is a human condition, known as Hand Foot and Mouth disease, which is unrelated to FMD, and does not affect animals.

— More about foot-and-mouth in England can be found here

Written by: Christian Nordqvist