Many farmers are bracing themselves for an influx of visitors to the countryside as folk get away for their Easter break. While most welcome those visitors and like to see them enjoying themselves, quite a few will be left with bad memories of a thoughtless, untidy, rude minority.

There are those who park cars in gateways and farm lanes blocking access for farmers' tractors and other vehicles as they go about spring work like sowing crops or lambing ewes. Worse are those who don't shut gates properly behind them allowing animals to escape or different batches to mix. Cattle and sheep that escape onto roads present a traffic hazard, while there can be injuries caused as a result of cattle from different batches fighting to establish a new "pecking order".

Dogs are increasingly a contentious issue, particularly those that are not kept on a lead. A dog may have run off for just a few minutes, but what was it up to in that time? Was it chasing pregnant sheep, or ewes nursing young lambs? The end results can be catastrophic. Pregnant ewes may miscarry, or young lambs drown in burns as they try to follow their panicked mothers. Worse, a "friendly", family pet may have seriously worried and injured sheep while absent.

It's is also important for those walking their dogs in the countryside to give cattle, particularly cows nursing young calves, a very wide birth. Such cows can be very protective of their calves and see dogs as a threat. As a consequence they will charge at the dog, but it in turn will lead the cows on to attack its "walker" as it runs back towards them for safety. Several people are killed or seriously injured every year this way.

Another vexatious issue farmers have with dog-owners in the countryside is that they don't "scoop their dogs poop" and dispose of it properly. Parasites found in some dog faeces can result in the abortions of cattle and death in sheep.

The two diseases of particular concern that can be caused by dog faeces on farmland are neosporosis and sarcocystosis. Neosporosis can cause abortions in cattle and is thought to be responsible for the highest percentage of all cattle abortions reported in the UK. Neospora eggs are produced by infected dogs and excreted in their faeces. Cattle will then become infected if they eat grass or drink water contaminated with the eggs.

Sarcocystosis is also caused by parasites, which can use dogs as intermediate hosts, and similarly the eggs are produced and excreted in faeces. There is currently no licensed vaccine or drugs available for these diseases.

Then there are those who vandalise the countryside by removing fence posts, or breaking up wooden gates to fuel camp fires - and of course the hundreds of tons of litter left strewn around our beautiful countryside. Why can't people take their rubbish home with them?

Of course one thing nobody wants to take home from their visit to the countryside is E. coli 0157.

E. coli 0157 is carried by animals, with ruminants (cattle and sheep) considered the main reservoir. They show no illness, but sporadically will pass the infection in their dung. As there is no way of identifying where or when 0157 has been shed then all cattle and sheep, or their dung, should be regarded as infected.

The main symptom is diarrhoea which may turn bloody. The worst cases can lead to death, while survivors may end up suffering lifelong problems from the debilitating Haemolytic Uraemic Syndrome (HUS), a complication affecting the kidneys that may leave the sufferer dependent on dialysis.

Handling animal dung is the most obvious method of infection, but touching animal hides or fleeces is another less obvious way. Playing on grassland that is contaminated by cattle or sheep droppings is another way.

The infection can be transmitted by handling balls or footwear that have been in contact with such grassland.

The most obvious precaution is to stay away from dung and thoroughly wash your hands before eating, as "turd to tongue" is the most common route of infection.

Don't listen to those who reckon that a little bit of dirt did them no harm when they were youngsters. E. coli 0157 is different to other, relatively harmless, strains of E. coli. It is a relatively new pathogen that was not identified until the 1980s and it produces a toxin that may kill.