By Alasdair Macnab

THE COVID 19 outbreak has drawn everyone’s attention to what biosecurity is really about. Disease needs pathways and opportunities to spread. Biosecurity is the process which, when well done, closes pathways and eliminates opportunities. When biosecurity is not done or not done well, it can actually help disease spread. What is happening with Covid 19 shows this very starkly.

Cleanliness, hygiene, disinfection and separation are the basics in stopping the spread of any disease. The current medical advice and government action to control Covid 19 is built on these basic principles. Similar measures were used to control foot-and-mouth disease in 2001.

Does the farming industry take biosecurity seriously? NO! Let me explain. Firstly, biosecurity is not just for animals. Biosecurity is for all diseases of plants, animals, the soil and humans.

Potato Cyst Nematode (PCN) is a disease of potatoes. It wipes out yields and is spreading at an exponential rate across Scotland; so quickly that experts estimate that somewhere between five and 25 years there will be no Scottish seed potato industry. How is this disease spreading? How do we stop this and other diseases? That is my task this month.

PCN remains in fields for up to 30 years. Tractors and machinery working these fields, even when growing cereals or grass, will pick up PCN on tyres, machinery, tractor operator footwear and leggings and take it from the field to the next destination and the next one. This is how fields become infected with PCN and unless a complete clean-down of all soil is undertaken between fields it will spread.

Why do we need biosecurity?

Biosecurity is a word in common use usually without definition or context. It means many things to some people and nothing to most. Even professionals struggle with it. It covers not just animal issues but plant and soil issues. We need to be aware of all three.

Over the last 40 years the development in treatments for disease in plants and animals has been exponential. Antibiotics have allowed more and more people to survive infection and surgery. Anthelmintics have reduced the impact of parasites across the globe. Pesticides have allowed bigger and better yields.

These halcyon days are passing. We have become complacent. African Swine Fever is a good example of a disease where there is no treatment or vaccine available. Spread can only be stopped by extremely good biosecurity.

Humanity now faces major challenges from climate change; drug resistance; disease spread and the loss of drugs and chemicals on which we have depended on to feed growing populations.

The farming industry has a significant role to play in tackling three of these challenges – antibiotic resistance, anthelmintic resistance and disease control. Is our approach to tackling with these issues fit for purpose? Are we prepared to recognise, acceptance and act on our weaknesses? What can we do to mitigate these issues?

Why raise the question of biosecurity now?

We had a visit from a young vet several years ago to do our annual cattle health scheme test. I stopped him before he took blood from the second cow as he had not changed the needle from the first cow. His response? “Oh you want biosecurity do you?"

Another vet came one day to assist with a calving. She did not park in our designated area for vets. She put on dirty leggings and boots. I stopped her before she came near the stock and demanded that everything be cleaned off and disinfected. A row ensued about the priority, calving the cow or biosecurity. It turned out she had Virkon with her as a disinfectant. Another discussion ensued. She did not know what the range of activity of Virkon was and that it would not kill acid fast bacteria like Johnes. I got some FAM30 and we got the calving done successfully.

Network Rail came last spring to do some drainage work on our farm. To access some areas they hired a portable roadway. As part of the access conditions I had insisted that no soil, debris or animal waste was to be brought onto the farm. The roadway arrived and had faeces and soil on it. The lorry bed was covered in soil. The load was taken away for cleaning. It came back the next day and was again sent back for further cleaning. The owner of the company was livid as it was costing him money. He agreed he had a copy of the Terms and Conditions for the job but had ignored it as it hadn’t been an issue before.

Why is biosecurity important? What are the facts?

I have highlighted the issue of PCN above and the evidence that is well established about it.

Animal disease – let’s start with some well established facts.

  • One gram of infected faeces can infect a calf with Johnes disease;
  • Six organisms is the infective dose of bovine TB;
  • Enough BVD can be carried on a fomite (a non-living object or material such as a jacket, silage bale, trailer, quad bike, etc) to infect many animals.

In other words, disease is spread by very small amounts of material.

Now think about the visitors to your farm. How many could bring that very small amount of faeces onto your farm? Pick from your vet, lorries and their drivers, tankers and their drivers, the AI man, the postman, company reps, utilities, contractors, visitors and then there is you and your vehicles, tractors and equipment. Where do they park? Are the vehicles clean? Can they drop or pick up small amounts of faeces, soil, and other material? What are they wearing? Is it clean? Has it been in contact with other animals, soil or other material?

Do visitors visiting farms regularly carry an approved disinfectant? If not, why not? Which one should they use? Have they got clean boots, leggings, and jackets to put on when they arrive? Do agronomists drive their vehicles through your fields? Where do lorries pick up and drop off their loads? Do contractors arrive with soil free tractors and machinery, clean boots and overalls? What are the risks to your business that you can accept and which are those you cannot?

What is biosecurity?

The original definition of biosecurity started out as a set of preventive measures designed to reduce the risk of transmission of infectious diseases in crops and livestock, quarantined pests, invasive alien species, and living modified organisms.

Australia takes a very hard line as those who have visited the country will know. They have a national biosecurity definition: –

'Biosecurity is protecting the economy, environment and people’s health from pests and diseases. It includes trying to prevent new pests and diseases from arriving, and helping to control outbreaks when they do occur. While robust response arrangements are in place to combat outbreaks, preventing pest and disease incursions in the first place, remains a national priority.'

Note the difference in language between the two definitions. The first is aimed at reducing disease transmission the second trying to prevent disease transmission and make that a national priority.

Does language matter in biosecurity?

A devastating disease, Phytophthora Ramorum, is affecting larch trees in Scotland with huge economic impacts. Scottish Forestry’s approach to biosecurity states: “As the busy summer holidays period approaches, members of the public are being urged to take some simple precautions which could help, such as cleaning their boots before leaving. When you leave, think about not moving stuff from this forest to another forest or another part of the countryside.”

Compare the language used in the Australian policy and the Scottish Forestry policy. Which more closely aligns to your language and approach to biosecurity? Do you use active or passive language? Do you take responsibility or do you pass responsibility to the visitor to your farm of croft?

Do you use ‘big’ words like biosecurity, quarantine and translocation? Do you understand these words or just think you do? Or do you use simple day to day language like clean, hygienic, disinfect, separation and spread?

Look at your farm health plan. Farms may have one for livestock. Why do we not have one for soil, plants and crops? Look at the language. Does it use words like consider, think about, suggest? Does it make you do it? Why does it not use words like the Australian approach or is it more like Scottish Forestry? Which approach will be more effective?

How does disease spread?

Vets are taught how infectious agents infect the animal, routes of transmission between animals e.g. aerosol, faeces. Agronomists are taught much the same with plant diseases. There seems to be little taught or understood about how infection moves between groups, herds and countries.

When tracing a notifiable disease APHA look at four key routes: – Animal, Personnel, Vehicle and Other. These are the four methods of transmission and each needs a different approach and process to stop spread through each of these routes.

Animal to animal is a route we are all familiar with. Stopping disease spread is easy. Keep them apart. Use vaccines. Use quarantine and testing to ensure new arrivals do not present a risk to your health status.

Personnel to animal or farm are routes we do not consider or control very well. Have we forgotten the lessons of 2001 or learned the lessons of BVD? How many of you welcome an agronomist, a vet, a salesman, a visitor onto the farm without ensuring their clothing, hands and foot wear are clean and disinfected?

Vehicle transmission is not even on the radar with many. Soil diseases, animal diseases and plant diseases can all be spread by vehicles. Driving into a field of cattle which then surround the vehicle, lick it, faeces get onto tyres, wheel arches etc and get shifted to the next field or farm the vehicle visits.

Other routes are even further off the radar. I recall during Foot-and-Mouth eventually tracing an outbreak to a load of silage bales which came from a farm which had been slaughtered out and mud from the farm got onto the bales and took disease to another farm.

Biosecurity levels and possible actions

In my last column, I described the four levels of disease, epizootic, endemic, herd and individual. Each of these diseases has its own method of stopping the spread and its own biosecurity rules.

  • Epizootic diseases are controlled by stopping national movements, high individual unit biosecurity and widespread testing;
  • Endemic diseases are controlled by restricting infected farms, individual farm biosecurity, testing the stock on the farm and neighbouring farms and allowing movements under licence;
  • Herd/flock diseases are managed by imposing farm restrictions and testing the animals;
  • Individual animal diseases are managed by on farm isolation or quarantine.

Let us consider attitudes to biosecurity in the light of these facts and that animal material can spread antibiotic and anthelmintic resistance. I shall do this with a series of challenges.

Farm and croft challenge (1)

A vet tests a mare and foal for equine influenza to allow the export of the foal from the UK. They both came back with positive results meaning the foal cannot be exported. The owner complains to the laboratory that a positive result is not possible as the foal was conceived by AI and the mare has had no contact with other horses.

The mare and foal are retested and a negative result is obtained. What went wrong? The vet who took the samples had vaccinated four horses with equine influenza vaccine earlier that day. Testing revealed that the virus found on the first test had come from the vaccine used. Virus had gone from his hands onto the animal and then onto the swab used for testing.

In the light if this story, and the disease facts above, how easy will it be for a visitor to your farm to transmit disease? What measures do you have in place to prevent a similar story on your farm or croft?

Farm and croft challenge (2)

A visitor arrives at your farm and puts on a pair of wellies like those in the picture. What are you going to do? Will you say nothing and hope for the best? Will you tell the person you’re not coming on here with these? Have you got a supply of wellies on farm for visitors? Have you got running water and a disinfectant boot wash at the visitor parking point? Do you have a visitor parking point? Do visitors walk around your farm in the same foot wear and clothing they walked round the previous farms they visited?

Consider the animal, plant and soil diseases I have already mentioned in this column. Disease like PCN can significantly reduce the value of your land. Are you happy to take this risk?

Farm and croft challenge (3)

You have been treating an animal for a couple of weeks and it is not recovering. You call the vet. The vet finds you have used three different antibiotics. The vet takes samples for antibiotic sensitivity. The result comes back as a multi-drug resistant antibiotic. It is the top performing animal in your herd or flock. What do you do? What are the risks?

Multi-drug resistant bacteria can infect humans. Have you got a young family? Have you got farm staff? What is your correct course of action here? Would your vet advise euthanasia of the animal or consider treatment with a human critical antibiotic? What is the correct route here? This is not a hypothetical question. Farmers and vets across the UK are already having this conversation. Do you carry out any investigation into spread of multi-drug resistance on the farm? What happens if it has spread? How did it get onto your farm in the first place?

Farm and croft challenge (4)

I was at a farm carrying out an assessment of a vet doing TB testing and saw a bottle of antibiotic on a wall beside the crush. It had been there for a while. I asked the young vet if there was anything in the area that should be of concern to him. He eventually spotted the bottle and I asked the vet what action should be taken. He knew he should draw the farmer’s attention to the incorrect storage of antibiotics and the risks to antibiotic resistance. However, he was reticent to address the issue as the farm was a large client of the practice.

Why should the threat of losing a client be larger in the mind than protecting animal and public health and minimising the risk of antibiotic resistance? Is this a responsible approach to the veterinary profession and society from some farmers? Why does the farmer, a member of QMS not appreciate the need for correct storage?

The ability and confidence does not just affect young vets. One of my assessor colleagues regaled us at an assessors meeting with an incident on their own farm. A vet arrived to do a TB test and the vet’s waterproofs and wellies and testing equipment was far from clean. My colleague did not feel able to say anything to the vet. We explored what it was that prevented comment on the standard of biosecurity. Are you afraid to challenge the cleanliness, hygiene and standards of anyone coming onto your farm? If so why are you afraid? It is your business that is at risk, not theirs.

Farm and croft challenge (5)

I challenged Network rail contractors about their standard of hygiene and cleanliness. They accepted they were wrong and put it right. Do utility companies access your land without cleansing and disinfecting vehicles, boots and clothing? What diseases are they spreading? What are you going to do about it?

Lessons to take away

Everyone and everything that comes onto and off a farm has a role in disease, both in spreading and preventing spread. This concept needs to be at the centre of our professional lives as farmers, crofters, contractors, vets, advisers, drivers etc. This thinking must be implemented without fear or favour. It’s called professional standards. It safeguards the industry, our soils, plants, animals, family, staff and the public.

Planning biosecurity for your farm needs a comprehensive review of the soil, plant and animal diseases involved by all those involved. It’s called a health plan. It should, I believe, be a farm wide biosecurity plan aimed at trying to prevent disease getting onto the farm, not just reducing the risks.

Language used in biosecurity discussions needs to be plain, clear, direct and unambiguous. There cannot be room for self interested decisions.

Biosecurity is not difficult. Clean it, disinfect it, don’t move it, keep it separate and no contact. We can do it. An example of very good biosecurity in practice is the production of gluten-free oats where any risk of gluten contaminating the crop must be eliminated. The skill does exist in the industry; we just need to apply across all our business.

Government should be encouraged to look at providing capital grants for the construction of biosecurity points on each farm and croft where vehicles and drivers can wash down and apply disinfectant before leaving the premises. Contractors should get funding to mount pressure washers on their machinery to wash down before leaving farms or in some cases infected fields. This type of investment over five years will go a long way to protecting the key capital of Scottish Farming PLC, its soil plants and animals.