Gastrointestinal roundworm parasitism in the curlew
Gastrointestinal roundworm (nematode) parasitism is a common condition in the Eurasian curlew (Numenius arquata), a wild wading bird sometimes admitted to wildlife rehabilitation centers. These worms live in the bird's stomach, intestines,...
What is it?
Gastrointestinal roundworm (nematode) parasitism is a common condition in the Eurasian curlew (Numenius arquata), a wild wading bird sometimes admitted to wildlife rehabilitation centers. These worms live in the bird's stomach, intestines, or caeca (small digestive pouches). They feed at the expense of their host and, when present in large numbers, can cause progressive weight loss and general weakness. This parasitic infection is closely monitored in weakened, injured, or hospitalized birds, where close quarters promote its spread.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
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Signs are often subtle at first. Progressive weight loss may occur despite maintained or decreased appetite, along with a dull, poorly groomed plumage and general lethargy with reduced activity. Digestive disturbances are possible, including abnormally soft stools—sometimes discolored or containing visible parasite debris. Mild abdominal bloating may develop with heavy parasite loads. In young curlews or birds already weakened by injury or exposure to contaminated environments, the condition can progress rapidly, with dehydration and marked depression.
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 nematodes (roundworms) parasitic in the digestive tract. Several genera may be involved in wading birds, including ascarids and worms belonging to families similar to those found in other shorebirds. Infection usually occurs through ingestion of eggs or larvae present in the environment (soil, water, mud) or through consumption of prey (invertebrates) that serve as intermediate hosts for certain parasites.
Young curlews, injured, weakened or stressed birds are more vulnerable. Living in dense groups, such as in wildlife rescue or rehabilitation centers, increases the risk of cross-contamination. A damp, muddy or poorly maintained environment favors the survival of parasite eggs and larvae. A natural diet rich in aquatic or tidal invertebrates increases exposure to certain indirect-cycle parasites.
Transmission
Contamination occurs mainly through the oral route, by pecking at substrate soiled with droppings from infected birds, or by consuming invertebrates (worms, mollusks, crustaceans) harboring larval stages. The parasite cycle depends on the nematode species involved: some have a direct cycle (no intermediate host), while others require passage through an invertebrate intermediate host.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
A veterinarian or wildlife specialist establishes diagnosis through a thorough clinical examination, combined with fecal analysis (coproscopic examination) to detect and identify parasite eggs. In some cases, endoscopy or post-mortem examination (if the bird has died) may confirm the presence of adult worms in the digestive tract.
Treatment
Treatment relies on broad-spectrum antiparasitic agents prescribed and tailored by a wildlife veterinarian. Nutritional support and rehydration may be added if the bird is significantly weakened. Treatment must always be individualized based on the species, the bird's general condition, and the severity of infestation.
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 living areas, avoiding moisture buildup and stagnant mud in captivity or care facilities. Regular monitoring of body condition and feeding behavior allows for early detection. Routine parasitological examinations (fecal analysis) are recommended for birds in rescue centers, especially when new individuals arrive.
Possible complications
Without treatment, massive infestation can lead to anemia, growth retardation in young birds, intestinal obstruction in severe cases, and general weakness that compromises survival chances, particularly in a wild bird already in poor condition.
When to see a veterinarian
The bird loses weight without apparent cause. Abnormal droppings or worms are visible in the feces. The bird becomes unusually depressed or less active. The belly appears swollen or the bird seems uncomfortable. Any curlew brought to a care facility showing persistent digestive signs.
Prognosis
The outlook is generally good if the infestation is caught early and treated appropriately.
It becomes more guarded in birds already weakened by injury, young age, or heavy untreated infestation, where the risk of complications and death increases.
Frequently asked questions
Is curlew parasitism dangerous for humans?
No, the digestive nematodes of curlews are not considered transmissible to humans. This is a disease specific to birds.
How does a wild curlew catch roundworms?
Generally by pecking at soil or mud contaminated with parasite eggs, or by eating small invertebrates carrying larvae.
Can you treat a wild curlew yourself?
No. A curlew is a wild protected bird that must be entrusted to a wildlife rescue center or a specialized veterinarian, the only ones authorized to diagnose and treat this type of parasitic disease.
How to tell if a curlew is parasitized?
The signs (weight loss, fatigue, dull plumage, digestive disorders) are not specific. Only a stool examination by a professional can confirm the presence of roundworms.
References
ESCCAP — European Scientific Counsel Companion Animal Parasites
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 22 August 2026
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