Leptospirosis is notoriously difficult to diagnose with symptoms easily mistaken for other common diseases
John Haugegard, technical manager at MSD Animal Health, explains the most prominent sign of the disease in a herd is poor fertility, post-service discharge, low litter size and increased abortion.
He says: “You should be vigilant if there is a history of porcine reproductive and respiratory syndrome [PRRS] in the herd, as the immunosuppressant nature of the disease may allow leptospirosis to quickly spread.
“Because it is difficult to confirm, we would always recommend working closely with your vet to develop a preventative approach to leptospirosis on farm.”
Mr Haugegard explains that a common route for leptospirosis onto pig units is pests.
“While not the original cause of the disease, rodents and wildlife are carriers of leptospirosis, so a robust rodent control plan is a must.”
“Leptospira [the bacteria] can survive in water, so good drainage for indoor systems stops urine and contaminated water pooling and spreading disease through the herd. Equally, this means outdoor systems may see outbreaks in autumn and winter when conditions underfoot are wetter.
“As with a lot of diseases, good biosecurity and management of incoming stock will minimise risk.
“Quarantine and test pigs as they come in, so you are confident in their disease status before they join the main herd.”
Lastly, and importantly, Mr Haugegard advises that it is vital to remember leptospirosis is a zoonotic disease, so steps must be in place to prevent transmission to your staff.
“Keep your farm staff fully trained on how to reduce the risk of human infection and provide them with the tools they need to do it.
“This includes excellent hygiene and handwashing, wearing gloves to handle afterbirths and covering cuts and lesions with plasters to prevent transfer.”
If anyone in contact with the animals shows flu-like symptoms and develops a bad headache, it is recommended they should visit their doctor as a matter of course to stop it from spreading further.
VET Paul Thompson, from Garth Pig Practice, says he will always consider leptospirosis if there is unexplained infertility, abortion or a rise in stillbirths.
But he says the challenge is confirming the diagnosis.
“We know the clinical signs of the disease are not unique to leptospirosis – there are many other things that can cause infertility, including management practices, porcine reproductive and respiratory syndrome [PRRS] and swine influenza.”
A further complication is the different antibody response in leptospirosis, compared to other common diseases in pigs.
“With a disease such as PRRS, you would carry out a paired serology test, taking bloods at the acute phase of the disease and again three weeks later. Typically, by that point, you would see a rise in antibodies and be able to confirm a disease.
“However, leptospirosis causes a low and transient antibody response, so by the time you test again, the level of antibodies will have fallen so you will not be able measure a change.
“As a result, leptospirosis tends to be a diagnosis by exclusion. Once we have ruled out all the other options – such as swine influenza, PRRS, management problems, mycotoxins, and fertility problems – we are left with a strong suspicion of leptospirosis.
“Until recently, there was no leptospirosis vaccine licensed in the UK for pigs, so we had to operate under a controlled special import certificate or conduct a therapeutic trial with antibiotics.
“Now there is a vaccine in the UK it makes tackling leptospirosis much easier and minimises the use of antibiotics. Now when we suspect leptospirosis, we can trial vaccination with our clients to see if it improves the situation.
“I would also strongly recommend a programme of vermin control. Vaccination alone is not going to work if you have an influx of rats. Anything you can do to lessen the weight of the challenge will help.”