November 13, 2013

After having spread from a single farm to 23 to date, an outbreak of infectious laryngotracheitis (ILT) has been creating a headache for poultry producers in Northern Ireland.

Northern Ireland has had "about half a dozen" outbreaks of ILT in the past, according to St David's Poultry Team vet Mike Alcorn, who has worked closely on this outbreak.

He said, "When we've had it, it's been a slow spreading disease, confined to one site and we've been able to get on top of it by depopulating. In the past it's been a virus from vaccination that's gone wild, but this is a novel field virus, behaving completely differently to what we've experienced until now."

The virus was first discovered on a commercial free-range laying unit near Ballymoney, North Antrim, in August.

Alcorn said an attempt to "slaughter out" the virus was thought to have been successful, until a large broiler unit about two miles away, developed classic signs of ILT.

A cluster of farms in the surrounding area has since become affected, spanning broiler breeders, laying birds and broilers.

According to Alcorn, the virus has had a heavy financial cost as well. In terms of layers, the minimum that they have experienced is a 15% drop in productivity, while some older flocks have ceased to lay.

He said the problem would probably be solved by routine vaccination, but those with multi-age sites faced a "series of unpleasant choices". The ILT vaccine has a propensity to revert to a viral form. You can vaccinate pullets when they arrive, and eventually see some spread, not vaccinate and hope for the best. Or you can vaccinate while in lay, he added.