(Part 3 of a four-part series on zoonoses)
The main zoonoses associated with scouring in very young ruminants and also farm animal abortions were discussed in Part 1 of this series. Part 2 looked at zoonoses associated with dogs and cats. This Part 3 deals with some other relatively common diseases of farm animals that can be spread to humans.
The biggest risks are from animals that are obviously unwell or diseased.
- They may have diarrhoea ,
- they may have aborted,
- they may have sores round their mouth
- or hairless crusty skin lesions.
The zoonoses that we will consider in this article are:
||sheep, cattle, horses, goats|
||cattle, dairy cows|
|Scabby mouth (orf)||lambs and goat kids|
One of the most serious zoonoses is salmonellosis, which makes humans and animals very sick indeed.
- It causes severe sometimes bloody diarrhoea and in pregnant animals it also causes abortion.
- Affected animals are very dull and they won't eat.
- The runny faeces are highly infectious and any human in contact with it can develop severe diarrhoea too.
- Scrupulous hygiene is needed when handling sick animals and their faeces - this means washing hands often, to get rid of even the slightest traces of contaminated material, and not putting soiled hands near your mouth.
- Remember too that soiled clothing can infect people who come in contact with it - such as children who come for a cuddle before overalls have been removed.
There are other types of bacteria that cause severe scouring (diarrhoea) in farm animals too - yersiniosis for example.
When handling any animal with diarrhoea, it's important to take the extra hygiene precautions outlined above.
Scabby mouth (also called orf) is a disease mainly of very young lambs and goat kids.
- It causes sores like cold sores around the mouth and even on the dam's teats.
- It's caused by a virus and it can spread to humans, causing nasty slow-healing ulcers just like bad cold sores.
- To prevent it, good hygiene is important, as is keeping hands away from the face after handling sheep and goats.
In all livestock, ringworm can cause crusty hairless lesions on the skin that can sometimes be itchy.
- The lesions are often roughly circular and spread out from the centre.
- The cause is a fungus, and fungal spores can be transferred from the animal's skin to human skin.
- Prevention involves knowing the risks and not putting anything that has been in contact with infected animals directly onto your skin.
- Some animals may carry the organisms that cause ringworm even when they don't have obvious lesions.
Not so long ago dairy farmers were at risk of developing a nasty flu-like disease called leptospirosis from their milking cows. Fortunately this disease is uncommon now because most dairy cows are vaccinated against leptospirosis. However non-vaccinated cows could still be carriers.
- Infected cattle, pigs and deer usually don't seem unwell but they excrete the leptospire bacteria in their urine.
- The bacteria infect humans by entering the body via urine splashes on skin cuts or grazes, and stockmen who work with dairy cows, deer and pig handlers can all be at risk.
There are various bacteria that thrive in wet wool. These can cause a crop of boils on shearers' bare legs and arms after close prolonged contact with damp or wet wool. The moral is, don't shear or crutch damp sheep, but if you do, wear protective clothing.
In spite of all the diseases listed here, remember that in general the risk of picking up disease from our farm animals is small, particularly if they don't have skin lesions, if they don't have diarrhoea and if they are apparently healthy in every other way. In fact you are far more likely to pick up disease from another person! Other humans could be spreading diseases like colds, flu, chicken pox, measles and hepatitis!
Nevertheless, don't forget to take basic hygiene precautions when handling livestock.
- Wear protective clothing when handling farm animals.
- Wash your hands after handling them and before eating, biting your nails or smoking!