Gastrointestinal parasitism in macaws (roundworms)
Gastrointestinal parasitism caused by roundworms (nematodes) is a common infestation in macaws, especially those living in outdoor aviaries or in contact with soil. The most frequently encountered worms are ascarids (Ascaridia) and sometime...
What is it?
Gastrointestinal parasitism caused by roundworms (nematodes) is a common infestation in macaws, especially those living in outdoor aviaries or in contact with soil. The most frequently encountered worms are ascarids (Ascaridia) and sometimes capillaries. They live in the bird's intestines and feed at the expense of its body, causing a gradual deterioration in overall health. This disease affects both young and adult birds, but young macaws are often more susceptible to the consequences of infestation.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Many parasitized macaws show no visible signs, especially in the early stages of infestation.
When signs appear, progressive weight loss may be observed despite normal or increased appetite, a dull and poor-quality plumage, diarrhea or abnormal droppings, and sometimes repeated vomiting or regurgitation.
In heavy infestations, the bird may appear depressed and less active, with an occasionally distended abdomen. Whole worms are sometimes visible in the droppings, which is a clear sign of infestation.
In young macaws, stunted growth or slower-than-normal development may be noted.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Infestation is caused by intestinal nematodes, mainly ascarids of the genus Ascaridia, sometimes other roundworms such as capillaries. These parasites lay eggs that are shed in the droppings of the infected bird and contaminate the environment, particularly the soil of aviaries.
The macaw becomes infected by ingesting infective eggs present on the ground, in contaminated food, in drinking water, or by pecking at contaminated organic debris. The cycle can be direct (the egg becomes infective in the environment) or involve an intermediate host depending on the parasite involved.
Macaws housed in outdoor aviaries with access to bare ground are at higher risk, as parasite eggs can survive for long periods in moist soil.
High bird density in the same space increases the risk of cross-contamination. Poor hygiene, inadequate cleaning of feeders and water bowls, or accumulation of droppings also promote transmission.
Young macaws and birds weakened by another illness or stress are more susceptible to clinical signs of infestation.
Transmission
Transmission occurs by ingestion of parasite eggs present in contaminated environments (soil, food, water soiled by infected droppings). There is no direct transmission from one bird to another without passage through the environment.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian diagnoses the condition through fecal examination (coproscopy), which allows parasite eggs to be detected under the microscope. Several samples may be necessary since egg shedding is not always continuous.
In some cases, additional testing such as blood work may be recommended to assess the bird's overall health, particularly if infestation is severe or complications are suspected.
Treatment
Treatment consists of administering antiparasitic drugs specific to roundworms, prescribed and dosed by the veterinarian according to the bird's weight and condition. Follow-up examination after treatment is often recommended to confirm effectiveness.
At the same time, thorough cleaning of the bird's environment is essential to prevent rapid reinfection by eggs already present in the surroundings.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention relies on good environmental hygiene: regular cleaning of aviary floors, frequent removal of droppings, and disinfection of feeders and water bowls.
Avoiding direct contact between the bird and untreated soil, or limiting access to areas where other birds may have defecated, reduces risk.
Regular fecal examinations by a veterinarian can detect infestation before clinical signs appear and allow a preventative worming protocol to be tailored if needed, especially for birds living in groups or outdoors.
Possible complications
Severe untreated infestation can lead to intestinal obstruction from worm accumulation, particularly in young birds. Marked weight loss and dehydration may develop gradually.
A chronically parasitized bird becomes more vulnerable to other infections due to weakening of its overall immune function.
When to see a veterinarian
The macaw shows progressive weight loss despite normal or increased appetite.
Worms are visible in the droppings.
The bird has abnormal stools or persistent diarrhea.
Feathers become dull without other explanation.
A young macaw shows growth delay.
The bird appears lethargic or less active than usual.
Prognosis
The prognosis is generally good when the infestation is detected and treated promptly, with complete recovery of the bird's general condition within a few weeks.
In the case of heavy or prolonged infestation, especially in a young parrot, the prognosis becomes more guarded due to possible complications such as intestinal obstruction or marked general weakness.
Frequently asked questions
Can an indoor macaw catch roundworms?
It's possible but less common than with a bird in an outdoor aviary. The risk exists if the bird has access to contaminated soil or if it's offered soiled food.
How can I tell if my macaw has worms without taking it to the vet?
There is no reliable way to know without examination. Many infested birds show no visible signs. Only a fecal examination by a veterinarian allows for a certain diagnosis.
Should you deworm a macaw even without symptoms?
This depends on the bird's lifestyle. The veterinarian may recommend regular parasite screening, especially for birds kept in outdoor aviaries, to determine whether treatment is necessary.
Can macaw worms be transmitted to humans?
No, intestinal roundworms from macaws are not transmissible to humans.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
WSAVA — World Small Animal Veterinary Association
Content reviewed by the TunisieVet editorial team · Updated 29 September 2026
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