Livestock medicines producer Elanco has warned free-range egg producers that there is an elevated risk of worms during the current housing order for avian influenza (bird flu).

The pharmaceutical company has warned producers to keep up with their worming regimes to lower the risk of an outbreak.

Business manager at Elanco, Jeremy Marsh, said that housed birds will come into increased contact with their own faeces.

“Due to the varying number of parasitic worms combined with the current way that laying hens are housed, the risk of these parasites causing production losses is inevitable,” he said.

“Although birds aren’t currently able to go outside, increased contact with faeces while in sheds means that worms are more easily picked up and spread.”

Marsh listed four different types of worms as the ones that pose the biggest threat to bird health and performance:

  • Roundworms;
  • Hairworms;
  • Caecal worms;
  • Gapeworms.

“While a heavy burden of any of the four main species can lead to disease, hairworms carry the greatest risk,” Marsh explained.


Hairworms can be found in the stomach and intestines of chickens. They are typically the smallest species affecting chickens and are almost invisible to the naked eye, Elanco said.

Marsh said that, despite their small size, hairworms are often considered to be the most dangerous parasite for birds and they can be fatal even in low amounts.

“The symptoms of hairworms vary but often lead to reduced egg production, weight loss, reduced food intake, diarrhoea, anaemia and death,” Marsh said.

“The most obvious symptoms are the birds looking stressed and generally unwell, appearing dull and hunched.”

Marsh said that, throughout the housing order for bird flu, egg producers should continue to follow standard worming protocols.

“Most birds are wormed in six-week intervals throughout the production cycle, with some exceptions upon veterinary advice,” he said.

“Because there are a number of different species that can be problematic, the ideal solution is to use a wormer that tackles all major species at all lifecycle stages, to give a full spectrum of control.”