What Causes Fungal Infections In Poultry?

Knowing the Signs and Symptoms of Chicken Illnesses Can Save Their Lives


By Brittany Thompson, Georgia

After my oldest hen and the matriarch of my flock, Chirpy, was diagnosed with a fungal infection through nose swab testing, I started to wonder what causes fungal infections?

Chirpy, a 6-year-old Rhode Island Red, was also diagnosed with bumblefoot.

The type of fungal infection was called Candida fumata. Chirpy had six different colonies of this fungal infection growing in her. It mostly affected her breathing. It was pricey testing, but worth finding out what was the cause of her respiratory issues since antibiotics were not working. My vet and I tried four different antibiotics before coming to the conclusion that her illness was not bacterial related. Symptoms are similar to respiratory infections and it is a common mistake to treat fungal infections as a respiratory infection, which only makes the fungal infection worse, as I found out.

In July 2015, Chirpy passed away from her fungal infection. I found her one morning under the roosts. I also had a Golden Comet hen, Little Worm, who was four, that recently passed from what I believe to be an internal fungal problem of digestion.

Rapid weight loss was noted, as well as decreased activity, eating more and fatigue.

What Is A Fungal Infection?

Fungi come in molds, mildews, yeasts, mushrooms, and toadstools. Of the more than 100,000 species of fungi only two kinds cause infections — yeast-like and mold-like.

What Causes Fungal Infections

By first knowing what causes fungal infections, preventing them will be much easier.

• Moldy food (especially processed poultry feeds or corn)

• Spores in the air or on surfaces

• Wet weather, high humidity, and heat, like found in the southern United States

• Bedding materials that mold especially easily, such as some kinds of hay

• Even after the bedding dries out, dangerous spores can remain

• Lack of good sanitation

• Direct contact with fungus on another infected bird

• Weak immune system

Types of Fungal Infections:

Mycosis: Fungal infections have gotten more common with the widespread use of antibiotics. Fungal infections tend to prey on birds with lower immunity. The use of antibiotics also kills the naturally occurring body flora residing in their system, which leads to a weakened immune system. Mycosis is grouped by two different methods:

Superficial: affects the skin or mucous membranes.

Deep: affects internal organs, usually the lungs or crop, which is what Chirpy had.

Moniliasis (sour crop, thrush): This is a disease that primarily affects the upper digestive tract of all birds and is characterized by whitish, thickened areas of the crop and proventriculus, erosions in the gizzard, and inflammation of the vent area. It is caused by a yeast-like fungus (Candida albicans). Poultry of all ages are susceptible to the effects of this organism. Chickens, turkeys, pigeons, pheasants, quail, and grouse are species most commonly affected as well as other domestic animals and humans. The Candida organism is widely spread and is found throughout the world. Moniliasis is transmitted by ingestion of the causative organism in infected feed, water or environment. Unsanitary, unclean water can be a nesting ground for the organism. The disease luckily doesn’t spread directly from bird to bird. The organism grows especially well on corn, so infection can be introduced by feeding moldy feed.This infection produces no specific symptoms.

Mycotoxicosis: It is known that certain strains of fungi (molds) growing in feed or feed ingredients can produce toxins that, when eaten by man or animals, can cause a very lethal disease called mycotoxicosis. The toxins produced by these fungi are very toxic and rivals the botulism toxin for toxicity. Mycotoxicosis is caused by ingestion of toxic substances produced by molds growing on feed, feed ingredients, and possibly litter. Several types of fungi produce toxins that may cause problems in poultry, but of primary concern are substances produced by the Aspergillus flavus fungi and are thus called aflatoxins. Aspergillus flavus is a common mold that grows on many substances and grows especially well on grains and nuts. Several other fungi also produce toxins that cause the disease, so be sure to keep litter as clean as possible. I would not recommend using hay or any litter that molds quickly.

Aspergillosis: Aspergillosis has been observed in almost all birds and animals, including in humans. The disease is observed in one of two forms; acute outbreaks in young birds with a high mortality in young birds, and a chronic condition affecting adult birds. This type of fungal infection is highly contagious. Birds must be in isolation if they have been diagnosed with this infection. The condition is caused by Aspergillus fumigatus, a mold or fungus-type organism. These organisms are present in the environment of all poultry. They grow readily on many substances such as litter, feed, rotten wood and other similar materials.The bird comes in contact with the organisms through contaminated feed, litter or environment. The disease does not spread from bird to bird. Most healthy birds can withstand repeated exposure to these organisms. Inhalation of large amounts of the infectious form of the mold or reduced resistance of the bird apparently results in infection. The more chronic form in older birds usually results in loss of appetite, gasping or coughing and a rapid loss of body weight. Mortality is usually low and only a few birds are affected at one time. If you do take your bird to the vet and has been confirmed to have aspergillosis, your bird will have to be put in isolation. (The website by MSU really helped explain aspergillosis the best.)


Aspergillus mold growing on a tomato.

Symptoms Of Fungal Infections

• Weakness due to intestinal fungi that does eat your bird’s food and can cause damage to organs that digest food.

• Overall uncoordination of the bird

• Difficulty breathing, gurgling noises, and respiratory symptoms. Air passages are restricted by fungi.

• Fatigue

• Bird may not be very interested in eating and is losing weight.

• Some bright green and watery droppings, also known as vent gleet. Droppings may stick to vent area.

• Anemia

• Infertility and reduction in laying.

• Respiratory system may be restricted and bird isn’t able to use panting to cool down as well as normal.

• Internal bleeding is possible.

• Death may occur from a prolonged, severe infection.

Possible Treatments/Prevention

• I have never personally tried Oxine AH, but have heard good things about it. It kills bacteria, viruses and fungi. It can be used by fogging or spraying coops and the surrounding area and any equipment used. It’s also used to treat water. More information on Oxine AH can be found by doing a Google search if interested.

• Keep litter as clean as possible. I recommend using sand and have been using this for many years in my coops. I also use PDZ and Red Lake Earth DE in my coops.

• If possible, get a veterinarian to test your chicken. The testing can narrow down the type of fungal infection your chicken has and proper medication can be found.

• Do not feed your chickens anything moldy. The best feed for chickens is as fresh as you can possibly get. Check the dates your feed was made. This date can usually be found stamped on the bottom of a feed bag. I do not use feed more than a month old, just in case.

• If the infection is really bad, medication might need to be used, but antifungals are pretty harsh on a bird’s system.

• Keep birds in well-ventilated areas.

Probiotics for chickens can be a good way to introduce more good bacteria to kill off the fungi. Just be careful how much probiotics you give your birds. Don’t overdo it. Also, do not combine antibiotics and probiotics at the same time.

• Fresh garlic is great as a natural antifungal. You can feed it directly in crushed up bits in their feed or use a liquid form in their water. There are many benefits of garlic for poultry.

• Raw, unfiltered from the mother apple cider vinegar added to their water can also help prevent infections.

• Damerow, Gail. The Chicken Encyclopedia. North Adams, MA: Storey Pub., 2012. Print.
• Dr. Campbell, Dean, Heart of Georgia Animal Care, Milledgeville, GA
• Mississippi State University Extension http://msucares.com/poultry/diseases/disfungi.htm
• Burek, Susan. Moonlight Mile Herb Farm

Now that you know what causes fungal infections in poultry, what changes if any, will you need to make?

Originally published in Backyard Poultry October / November 2015 and regularly vetted for accuracy.


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