Gastrointestinal roundworm parasitism in the Bee-eater
The Bee-eater (Merops apiaster) is a wild insectivorous bird, sometimes brought to wildlife care centers or kept in aviaries by bird enthusiasts. Like many wild birds, it can harbor roundworms (nematodes) in its digestive tract. This parasi...
What is it?
The Bee-eater (Merops apiaster) is a wild insectivorous bird, sometimes brought to wildlife care centers or kept in aviaries by bird enthusiasts. Like many wild birds, it can harbor roundworms (nematodes) in its digestive tract. This parasitism is common in birds living in the wild and does not always cause visible signs, but it can become problematic in a weakened animal, a young bird, or one kept in captivity under poor conditions.
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:
Most infested Bee-eaters show no outward signs, especially if the worm burden is light.
When parasitism becomes heavy, gradual weight loss despite maintained appetite may occur, or conversely, a decrease in appetite.
Droppings may become soft or more watery than normal, and sometimes small whitish, thread-like roundworms are visible in the stools.
The bird may appear tired, less active, with dull or ruffled plumage.
In young Bee-eaters, stunted growth or delayed development of feathering is possible.
In severe cases, dehydration and greatly deteriorated overall condition may develop.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Parasitism is caused by roundworms (nematodes) that colonize the intestine, stomach, or sometimes other digestive organs of the bird. These parasites belong to families typically found in insectivorous and wild birds, such as ascarids or capillaries. The bird becomes infected by ingesting eggs or larvae present in the environment, or by consuming insects that serve as intermediate hosts for certain of these worms.
Young birds, with immature immune systems, are more susceptible.
A soiled, damp environment, or high bird density (in care centers or aviaries) favors the buildup of parasite eggs and reinfection.
A Bee-eater already weakened by injury, illness, stress, or inappropriate diet in captivity tolerates even moderate parasitism less well.
Exposure to heavily parasitized prey (insects) increases the risk of infestation.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian first reviews the bird's history—whether it comes from the wild or captivity, its general condition, and any symptoms—and performs a thorough clinical examination.
A stool sample analyzed under the microscope is needed to confirm the diagnosis and identify parasite eggs.
In some cases, additional tests such as blood work or X-rays may help assess the overall impact of the parasitosis.
Treatment
Treatment involves antiparasitic medications chosen and dosed by a veterinarian experienced in wild or exotic bird care.
Additional supportive care such as rehydration and nutritional supplements may be needed in weakened birds.
Thorough cleaning of the bird's environment is essential alongside treatment 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
In care centers or captivity, hygiene is essential: regular cleaning and disinfection of cages, aviaries, and feeding equipment, with prompt removal of droppings.
Avoiding overcrowding and isolating new arrivals during veterinary assessment limits spread.
Regular parasitological monitoring (fecal examination) allows detection of infestation before clinical signs appear.
For a wild bird in care, quarantine with parasitological screening before release or contact with other birds is recommended.
Possible complications
Significant untreated intestinal parasitosis can lead to severe malnutrition, dehydration, and reduce the bird's ability to fight off other infections.
In young birds, this may permanently compromise growth and development.
In severe cases, intestinal blockage from worm accumulation is possible, though rare.
When to see a veterinarian
Visible worms in the bird's droppings.
Progressive weight loss despite normal or increased appetite.
Persistent diarrhea or abnormally soft droppings.
Marked lethargy, ruffled feathers, or dull plumage lasting more than a few days.
Any young bee-eater showing apparent growth delay.
Prognosis
The outlook is generally good when parasitosis is detected early and treated properly with good environmental hygiene management.
It becomes more guarded in birds already weakened, very young, or carrying a heavy parasite load not addressed promptly.
Frequently asked questions
Does a wild bee-eater necessarily have worms?
A certain level of parasitism is common and often well tolerated in healthy wild birds. It is not systematically a problem, except if the bird is weakened or heavily infested.
Can you see worms with the naked eye?
Yes, some adult roundworms can be visible in stool as small whitish threads. However, their absence does not rule out parasitism, as stool examination is more reliable.
Can this parasitism be transmitted to humans or other animals?
Round worms specific to birds such as the bee-eater are generally not transmissible to humans. The risk of contamination mainly concerns other birds sharing the same environment.
Should a bee-eater systematically be treated in a rehabilitation center?
A parasitic assessment is recommended before any treatment, to avoid unnecessary treatment and to target the correct type of parasite if needed.
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 20 August 2026
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