Manatee gastrointestinal parasitism (roundworms)
Gastrointestinal parasitism by roundworms (nematodes) is a parasitic disease affecting the digestive system of the manatee. These herbivorous marine or freshwater animals can harbor different nematodes in their digestive tract. A low parasi...
What is it?
Gastrointestinal parasitism by roundworms (nematodes) is a parasitic disease affecting the digestive system of the manatee. These herbivorous marine or freshwater animals can harbor different nematodes in their digestive tract. A low parasite load often goes unnoticed, but a significant infestation can affect the general health of the animal, particularly in young, weakened subjects or kept in captivity or in a care center.
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:
The signs are often discreet and non-specific. An infested manatee may show a progressive loss of appetite, weight loss despite an apparent normal diet, and general fatigue with less swimming activity. The stomach may feel swollen or tender. The stools may become loose, and in some cases worms or worm fragments may be visible in them. In an already weakened animal, parasitism can worsen a precarious state of health.
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 the presence of nematodes (roundworms) in the manatee's stomach or intestine. Several genera of nematodes have been reported in sirenians. These parasites thrive in the digestive tract and, depending on their numbers, can disrupt digestion and absorption of nutrients.
Young animals, stressed, malnourished individuals or recently collected in a rehabilitation center seem more susceptible to a clinically significant infestation. Poor water quality, promiscuity with other infested animals, or an immune system weakened by another disease also favor the clinical expression of parasitism.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The diagnosis is based on clinical observation associated with a parasitological examination of the stools (search for worm eggs) carried out by a veterinarian specializing in wildlife or aquatic fauna. A blood test can complete the assessment to assess the general condition and detect anemia or inflammation. Direct observation of worms in the stool can guide the diagnosis but does not replace it.
Treatment
Treatment is based on the use of antiparasitics belonging to the anthelmintic family, prescribed and adapted by a veterinarian specializing in aquatic wildlife. Nutritional support and close monitoring of the animal generally accompany treatment, particularly in weakened subjects.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention is based on regular monitoring of the health of animals, particularly in captivity or in care centers, with parasitological checks of stools. Maintaining good water quality, a suitable diet and limiting stress help to reduce the risk of massive infestation. Quarantine of new arrivals and hygiene of ponds are useful measures in captivity.
Possible complications
A massive and untreated infestation can lead to severe weight loss, dehydration, partial obstruction of the digestive tract in extreme cases, and a general weakening of the animal in the face of other diseases. In a manatee already in distress (injury, associated illness), parasitism can worsen the overall prognosis.
When to see a veterinarian
Loss of appetite or persistent refusal of food
Visible weight loss or loss of muscle mass
Marked decrease in activity or swimming
Abnormally swollen stomach or repeated loose stools
Presence of visible worms in the stools
Prognosis
The prognosis is generally favorable when the infestation is detected early and treated by a specialist veterinarian, especially in an otherwise healthy animal. It becomes more reserved in young animals, already weakened, or in the event of delay in treatment, due to the risk of digestive and general complications.
Frequently asked questions
Is roundworm parasitism common in manatees?
Low parasite load is common and often inconsequential. Clinically important infestations are mainly observed in weakened, young animals or in care centers.
Can we see worms with the naked eye?
In some cases of heavy infestation, worms or fragments may be visible in the stool, but their absence does not mean that the animal is unharmed.
Can a wild manatee be treated?
Yes, but only by a veterinary team specializing in aquatic wildlife, generally within the framework of a care or rehabilitation center.
Is this disease transmissible to humans?
No, manatee gastrointestinal nematodes are not considered transmissible to humans.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 24 September 2026
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