One year after an avian influenza outbreak in Indiana, poultry in the state are free of the virus.

Last year, an outbreak of the avian flu contaminated 10 commercial turkey farms in Indiana, and more than 400,000 birds had to be killed to contain the virus. But so far this year, there are no cases of the virus in the state.

Indiana Board of Animal Health Public Information Director Denise Derrer says there’s no obvious reason why an outbreak occurs in a particular year.

“It really is a hit or miss proposition, and we really don’t know what exactly makes one year so severe and one year not. And the randomness of it, it can be pretty frustrating.”

The virus is often carried by water fowl and spreads through bird droppings or bird-to-bird contact. It spreads most quickly during the spring and fall, when carrier birds migrate across the country.

Derrer says although there is no current outbreak in Indiana, farmers should take the threat of avian flu seriously and follow preventative measures.

“There’s always risk out there and I think that’s important for bird owners to realize. So they shouldn’t just treat this lightly.”

Preventative measures include limiting exposure to wild birds, wearing separate work clothes and shoes around domestic birds and keeping any new birds separate from the flock until their health can be assessed.