A Massey University scientist has warned flood-hit Northland farmers to be aware of the increased risk of leptospirosis in their livestock.
It's a highly infectious and debilitating disease that can also be passed on to people coming into contact with sheep, cattle and deer.
Leptospirosis is spread through the urine of infected animals and Dr Jackie Benschop, one of a Massey University team that's been researching the disease, said because of that, there was an increased risk when farms were flooded.
"Lepto's a bug that just loves the water and that's actually how it's spread. It's a bug that lives in the animal's kidneys and then comes into the bladder, comes into the urine, and then when the animal piddles, that urine goes onto the pasture or perhaps can splash onto another animal or human."
Dr Benschop said in a situation like that in Northland that water sits on the pastures.
"You can imagine that lepto could easily spread from animals to other animals through the water on the pasture and also to humans, perhaps not when we've got the severe, very deep flooding but when that recedes a bit as we hope it will in the next few days. This is where we might expect to see some lepto outbreaks."