Gastrointestinal parasitism in African grey parrots (roundworms)
Gastrointestinal parasitism caused by roundworms (nematodes) is a common disease in African grey parrots, particularly in birds kept in outdoor aviaries or in contact with soil. These worms live in the intestines and feed at the bird's expe...
What is it?
Gastrointestinal parasitism caused by roundworms (nematodes) is a common disease in African grey parrots, particularly in birds kept in outdoor aviaries or in contact with soil. These worms live in the intestines and feed at the bird's expense, causing progressive deterioration of overall condition. Infestation can remain inconspicuous for a long time before visible signs appear.
The main roundworms involved are ascarids (Ascaridia) and sometimes capillaries (Capillaria), which affect the small intestine. Heavy infestation can impact growth in young birds and overall health in adults.
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 infested birds show no visible signs, especially if the worm burden is low.
When signs do appear, progressive weight loss may be seen despite sometimes preserved appetite, dull and neglected plumage, diarrhea or abnormally soft droppings, occasional regurgitation or vomiting, abdominal bloating, and general lethargy.
In young parrots, stunted growth or poor feather development may be observed.
In cases of very heavy infestation, worms may be visible directly in the droppings.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by intestinal nematodes, mainly ascarids of the genus Ascaridia and sometimes capillaries of the genus Capillaria. The bird becomes infested by swallowing parasite eggs present in contaminated surroundings, on soil, perches, or food. Some worms have a direct cycle (the egg becomes infective in the environment) while others require an intermediate host such as an insect.
Birds housed in outdoor aviaries or in direct contact with the ground are most at risk, especially in warm, humid climates that favour egg survival.
Insufficient cleaning of the cage, aviary, or food dishes increases the risk.
Overcrowding, stress, poor diet, or a weakened immune system promote parasite establishment and multiplication.
Young birds are generally more susceptible than adults.
Transmission
Contamination occurs through ingestion of parasite eggs present in droppings, soiled bedding, soil in outdoor aviaries, or contaminated water and food. Birds kept in contact with soil or housed in poorly maintained aviaries are particularly at risk. Some parasites can also be transmitted via an insect or invertebrate serving as an intermediate host.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian makes the diagnosis by performing a parasitological examination of faeces, called faecal flotation, which allows parasite eggs to be identified under the microscope. Several samples may be needed because egg shedding is sometimes irregular. A complete physical examination of the bird is also performed to assess its general condition.
Treatment
Treatment relies on administering an antiparasitic medication suitable for birds, prescribed and dosed exclusively by the veterinarian according to the animal's weight and the parasite species identified.
A faecal test after treatment is often recommended to verify treatment effectiveness.
Nutritional support may be offered as an additional measure in weakened birds.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Regular cleaning and disinfection of the cage, aviary, food dishes, and perches substantially reduce the risk of infestation.
Avoiding direct contact between birds and the ground or installing an easy-to-clean substrate reduces exposure to parasite eggs.
Regular veterinary check-ups with faecal examination allow detection of infestation before clinical signs appear.
Quarantine of new birds before introduction to an existing aviary is an important preventive measure.
Possible complications
Untreated heavy infestation can lead to intestinal obstruction from worm accumulation, severe weight loss, dehydration, and general weakness that makes the bird more vulnerable to other diseases. In young birds, lasting growth retardation is possible.
When to see a veterinarian
The bird shows persistent diarrhoea or abnormal faeces.
Weight loss occurs despite maintained appetite.
Plumage becomes dull and the bird appears lethargic.
Worms are visible in the droppings.
A young parrot shows growth retardation.
Prognosis
The prognosis is generally good when the infestation is detected and treated early, with complete recovery of the bird's general condition. In cases of heavy infestation or delayed treatment, the prognosis becomes more guarded, particularly in young birds or those already weakened.
Frequently asked questions
Can an indoor grey parrot catch roundworms?
Yes, even though the risk is lower than in an outdoor aviary. Contamination can occur through soiled food, poorly maintained bedding, or contact with another infested bird.
How to tell if your parrot has worms? Signs include: - Weight loss despite eating normally - Diarrhea or loose stools - Visible worms in droppings or vomit - Lethargy and reduced activity - Ruffled feathers - Loss of appetite - Abdominal swelling - Breathing difficulties If you notice any of these symptoms, consult an avian veterinarian immediately. They can perform a fecal test to confirm the diagnosis and prescribe appropriate treatment.
Only a fecal examination performed by a veterinarian, called coproscopy, can confirm the presence of parasites. Visible signs such as weight loss or diarrhea often appear only at a late stage.
Can you give a preventive antiparasitic medication without veterinary advice?
No, it is strongly advised against administering an antiparasitic without a prescription. The dosage must be adjusted to the bird's weight, and certain products can be toxic if misused.
Can these worms be transmitted to humans?
Intestinal nematodes in parrots are specific to birds and pose no risk of transmission to humans.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
Content reviewed by the TunisieVet editorial team · Updated 28 August 2026
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