Gastrointestinal roundworm parasitism in the gray potoo
Gastrointestinal parasitism caused by roundworms (nematodes) is a common condition in the gray potoo (Nyctibius griseus), a nocturnal insectivorous bird often encountered in captivity at wildlife care centers and avian collections. These pa...
What is it?
Gastrointestinal parasitism caused by roundworms (nematodes) is a common condition in the gray potoo (Nyctibius griseus), a nocturnal insectivorous bird often encountered in captivity at wildlife care centers and avian collections. These parasites live in the bird's intestine and feed partly at its expense, causing progressive weakness. In wild-caught or captive birds, this type of parasitism is a frequent cause of poor general condition.
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:
Signs are often subtle at first. Progressive weight loss is seen despite appetite sometimes remaining normal, with a dull and poorly maintained plumage, decreased activity and reduced alertness compared to the bird's usual behavior. Abnormal droppings that are softer or changed in appearance may develop. In heavy infestations, worms may occasionally be visible in the feces. An enlarged or distended abdomen or digestive discomfort can also occur. Young birds or weakened individuals (after capture, transport, or stress) are more susceptible and may show more pronounced signs such as vomiting or marked lethargy.
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 nematodes (roundworms) that colonize the bird's digestive tract, particularly the intestine. Eggs from these worms are shed in the feces of the parasitized bird and contaminate the environment (perches, ground, food, water). The gray potoo becomes infected by ingesting eggs or larvae present on prey (insects) or in a contaminated environment, especially in captivity where space is restricted and substrate renewal is less frequent than in the natural habitat.
Confinement in an aviary or cage promotes the accumulation of parasite eggs in the environment. Stress (recent captivity, transport, injury) weakens the bird's natural defenses and facilitates parasite establishment. Inadequate enclosure hygiene, high bird density, or the absence of regular parasite control increase the risk. Young individuals and already weakened birds are more vulnerable to severe infestations.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
A veterinarian specializing in exotic birds establishes the diagnosis through a thorough clinical examination and a fecal analysis (coproscopic examination) to identify parasite eggs under the microscope. In some cases, more detailed testing (endoscopy, blood work) may be necessary to assess the overall impact of the infestation on the bird's condition.
Treatment
Treatment relies on giving antiparasitic medications specific to birds, prescribed and dosed only by a veterinarian experienced in avian medicine, as the safety margin can be narrow in these species. Supportive care (rehydration, nutritional supplementation) may be added based on the bird's overall health. Thorough cleaning of the environment must accompany medication to prevent immediate reinfection.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Regular and thorough cleaning of enclosures, perches, and surfaces in contact with feces limits the buildup of parasite eggs in the environment. Frequent substrate renewal and good humidity management reduce larval survival. Periodic preventive parasite control performed by an avian veterinarian is recommended for captive birds, especially when a new individual arrives. Quarantine of new arrivals before integration into the group is also a useful measure.
Possible complications
Heavy infestation left untreated can lead to severe weight loss, dehydration, anemia, and general weakness that may threaten the bird's survival, especially in young or already weakened individuals. Partial intestinal blockage is possible with very high parasite loads.
When to see a veterinarian
The bird is losing weight noticeably or its plumage becomes dull
Fecal appearance changes persistently or worms are visible in the droppings
The bird is unusually lethargic, inactive, or refuses to eat
Any captive guacharo bird newly arrived or before reintegration into a group
Prognosis
The outlook is generally good if infestation is detected and treated early, with a strong response to antiparasitic treatment combined with improved environmental hygiene. Without treatment, the outcome may be poor in young or already weakened birds, with a risk of progressive weight loss and complications.
Frequently asked questions
Is parasitism by roundworms common in captive potoos?
Yes, this is a frequently encountered condition in insectivorous birds kept in captivity, particularly in wildlife rehabilitation centers, due to prolonged contact with an environment that may harbor parasite eggs.
Can you see worms with the naked eye?
In cases of severe infestation, worms may be visible in the droppings, but in most cases only microscopic examination of feces by a veterinarian can detect parasite eggs.
Can this disease be transmitted to humans or to other animals?
Gastrointestinal nematodes in birds are generally not transmissible to humans. However, they can spread to other birds sharing the same environment, which is why hygiene and quarantine are important.
Can a treated potoo become reinfested?
Yes, if the environment is not cleaned in parallel with drug treatment, reinfestation through ingestion of new parasite eggs remains possible.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
WSAVA — World Small Animal Veterinary Association
Content reviewed by the TunisieVet editorial team · Updated 04 September 2026
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