The northern fowl mite (Ornithonyssus sylviarum) is the most serious external parasite of chickens. It is the most common one occurring in cool climates. It often infests wild birds, and birds can readily introduce it into a coop.
The northern fowl mite lives its entire life on a bird, feeding on blood. Female mites lay their eggs on feathers. Young mites hatch and complete their entire life cycle in approximately 7 to 14 days. Any infestation therefore rapidly gets worse.
As a result of irritation, these mites cause chickens to scratch. And loss of blood from mite bites can cause anemia. As a consequence, egg laying drops among hens and fertility goes down in roosters.
The tropical fowl mite (Ornithonyssus bursa) — also called bird mite or starling mite — resembles the northern fowl mite. In contrast to the northern fowl mite, though, it is more common in the warm southern states. And it lays eggs in nests as well as on feathers.
The tropical fowl mite is spread by starlings and other wild birds nesting in the eaves of a chicken coop. When the wild birds abandon their nest, the mites move into the coop. Both types of mite can therefore be prevented by taking measures to keep wild birds away from chickens.
Avian influenza, or bird flu, is caused by several different type A orthomyxoviruses. The natural hosts for type A influenza viruses are wild aquatic birds. They include seabirds (such as gulls and terns), shorebirds (such as plovers and sandpipers), and waterfowl (such as ducks and geese).
These natural hosts do not typically show signs of disease. But they can spread the virus among themselves and to other bird species, including chickens.
Avian flu comes in many forms. Signs therefore vary widely. They may relate to:
- respiration — coughing and sneezing
- digestion — appetite loss and diarrhea
- reproduction — drop in laying, reduced fertility, soft-shell eggs
- nerves —twisted neck or wing paralysis
- or numerous sudden deaths of apparently healthy birds
This virus spreads in secretions from an infected bird’s nostrils, mouth, and eyes and in its droppings. It travels from bird to bird through sneezing and coughing.
The main way bird flu spreads from wild birds to poultry, though, is through droppings. And bird droppings may be spread on contaminated equipment or the shoes of humans. Chickens that recover remain carriers.
The microscopic protozoan parasite Trichomonas gallinae occasionally infects chickens, causing sores in the mouth and throat. It is also known as trichomoniasis, canker, or sometimes roup.
This disease primarily affects domestic pigeons and wild doves. It may spread to chickens by way of drinking water contaminated with saliva from an infected bird’s mouth, or feed contaminated with infective saliva or droppings.
These protozoa live in the upper digestive system of an estimated 80% or more of all pigeons. But not all infected pigeons show signs of illness.
Trichomonads that invade a bird rapidly multiply. Signs of infection include:
- breathing with the neck extended and mouth open
- drooling and repeated swallowing
- yellowish-white cheesy patches in the mouth and throat
- asymmetrical appearance of the face, sometimes such that the two halves of the beak can’t properly meet
- difficulty eating, with accompanying weight loss or failure to gain
- pendulous crop
- sometimes watery or sticky eyes
- sometimes diarrhea
- rarely wobbling and other nervous signs
The disease may be mild. But it can also be rapidly fatal, depending on the virulence of the protozoa. Death is often the result. But not from the trichomonad infection. Rather, from a secondary bacterial infection invading the damaged tissue and becoming septicemic. Recovered birds remain carriers, although they are immune to reinfection.
To prevent canker, keep pigeons and doves away from chickens. Locate chicken feeders and drinkers where wild birds can’t gain ready access.
Canker spreads more readily in water than in feed. So do not let chickens drink from a birdbath. Or from any source of stagnant water that may be visited by wild birds.
And that’s today’s news from the Cackle Coop.
Gail Damerow is author of The Chicken Health Handbook.