Gastrointestinal parasitism in the dugong (roundworms)
Gastrointestinal parasitism in the dugong is an infestation of the digestive tract by roundworms (nematodes). These parasites live in the animal's stomach or intestines and feed at its expense. The dugong is a herbivorous marine mammal that...
What is it?
Gastrointestinal parasitism in the dugong is an infestation of the digestive tract by roundworms (nematodes). These parasites live in the animal's stomach or intestines and feed at its expense. The dugong is a herbivorous marine mammal that grazes on seagrass; this lifestyle exposes it to the accidental ingestion of parasitic larvae present on plants or in the water. Light infestation often goes unnoticed, but a heavy parasite load can seriously weaken the animal, especially if it is already compromised by other factors (injury, pollution, stress).
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 and nonspecific in this wild species that is difficult to observe closely. Progressive weight loss may be noted despite apparently normal feeding. The animal may appear more lethargic, swim with less vigor, or surface to breathe less actively. Digestive disturbances such as abnormally soft stools can be observed in stranded or hospitalized individuals. Since dugongs lack fur, the focus is rather on a dull skin appearance or loss of the usual smooth skin texture when in poor condition. In severe cases, abdominal bloating or belly distension may occur.
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 dugong's stomach or intestines. Several genera of marine nematodes are known to parasitize sirenians (the group that includes dugongs and manatees). The animal becomes infested by ingesting larvae present in its environment, particularly while grazing on seagrass where eggs or larvae may settle.
Young dugongs and weakened or malnourished individuals are more susceptible to severe infestation. Degradation of seagrass beds, which forces dugongs to feed in less favorable or more polluted areas, can increase the risk of parasite exposure. Environmental stress (coastal water pollution, human activity, climate change affecting seagrass beds) can weaken the animal and worsen the consequences of parasitism. Individuals already injured or ill, particularly those admitted for care after stranding, are especially vulnerable.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Diagnosis is based mainly on examining a stranded, captured, or dead animal. Faecal analysis allows parasitic eggs to be identified under the microscope. During a necropsy, direct observation of worms in the stomach or intestines confirms the diagnosis. In living animals receiving care, blood tests can suggest inflammation or anaemia consistent with significant parasitism, but they do not replace faecal analysis.
Treatment
A dugong admitted to a rehabilitation centre may receive antiparasitic treatment suitable for marine mammals, decided by the specialist veterinary team. Nutritional support and rehydration often accompany care of a weakened animal. Treatment is not possible in the wild; management applies only to stranded or captive animals.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There are no individual preventive measures that can be applied in the wild for this protected species.
Preserving seagrass beds, which are the dugong's habitat and food source, remains the best way to maintain healthy populations that are less vulnerable to severe parasitic infections.
Limiting coastal water pollution and reducing human disturbance also indirectly help dugongs resist parasites.
In captivity or rehabilitation centres, regular veterinary monitoring enables early detection and treatment of any parasitic infestation.
Possible complications
Severe untreated infestation can lead to anaemia, marked weight loss, and general weakness. This may reduce the animal's ability to feed effectively or escape danger, and worsen the outlook if another illness or injury is present. In rare cases, intestinal obstruction from very heavy parasitic burden has been reported in sirenians.
When to see a veterinarian
Finding a stranded, weak, or underweight dugong on the coast.
Observing an animal in a rehabilitation centre with persistent diarrhoea or unexplained weight loss.
Any dugong that is handled for care should receive a complete veterinary examination including parasite screening.
Report to a stranding network or competent authority if an animal in distress is observed.
Prognosis
The outlook depends heavily on the intensity of infestation and the animal's general condition. Light infestation in an otherwise healthy dugong usually does not cause serious consequences. However, in an already weakened, malnourished, or injured animal, heavy parasitic burden can significantly contribute to decline or death, especially without care.
Frequently asked questions
Can gastrointestinal parasitism in dugongs be transmitted to humans?
No, there is no evidence that these nematodes specific to sirenians pose a risk to humans.
How does a wild dugong catch these worms?
They accidentally ingest them while grazing on seagrass beds, where parasitic larvae may be present.
Can wild dugongs be treated for these parasites?
No, treatment is only possible if the animal is captured for care, for example after a stranding. It is impossible to treat a dugong in the wild.
Is this parasitism frequent in dugongs?
Light to moderate nematode infestations are commonly reported during necropsies of stranded dugongs, but they are not always the primary cause of death.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 24 August 2026
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