Caecal worms
The caecal worm (Heterakis gallinarum) doesn’t tend to cause health issues in poultry by itself, however it can be a carrier of another parasite that causes blackhead disease.
Blackhead disease can be a devastating disease in turkeys, affected birds look hunched over, fluffed up, depressed and often have sulphur yellow diarrhoea that sticks to the feathers around the vent, there are no treatments for this, and sadly affected turkeys will die.
The effects of blackhead disease in chickens are much less severe but it can cause peritonitis. It rarely affects waterfowl … however, all poultry can be carriers (it’s one of the reasons not to mix different species of poultry)
The parasite responsible for blackhead is Histomonas meleagridis, it’s a tiny parasite that’s carried by the caecal worm. The caecal worm passes its eggs (which carry the parasite) into the birds faeces, so the environment becomes contaminated. Birds then pick up the worm eggs from the contaminated ground when pecking around, and become infected.
Just to complicate matters, earth worms (most chickens favourite snack) can play a part in spreading the parasites, earth worms can ingest the caecal worm eggs from contaminated ground becoming a carrier for the caecal worm egg, and the blackhead parasite!
The good news is that testing your birds regularly for worms by performing a worm egg count, will help to identify what worms are present in your birds. Some types of worms can actually be beneficial to boost the birds natural immunity against parasites.
Using a wormer just in case, is not advisable as it may not be an appropriate wormer for the type of worm(s) present, and it will encourage the worms to become resistant to future treatments. We don’t have many treatment options for worms, so let’s all do our bit to preserve them for when they really are needed.