Gastrointestinal parasitism in indri (roundworms)
The indri (Indri indri) is the largest of the living lemurs, a species native to Madagascar that is currently threatened with extinction. Like many primates, it can harbour roundworms called nematodes in its digestive tract. This gastrointe...
What is it?
The indri (Indri indri) is the largest of the living lemurs, a species native to Madagascar that is currently threatened with extinction. Like many primates, it can harbour roundworms called nematodes in its digestive tract. This gastrointestinal parasitism affects mainly animals kept in captivity or living in fragmented habitats where population density and contact with faeces are greater. In a healthy wild animal, a light parasite load is often tolerated without visible signs, but an imbalance can quickly weaken the animal, especially young or debilitated individuals.
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. Diarrhoea or unusually soft stools may be seen, sometimes with worms visible to the naked eye. The animal eats less, loses weight gradually, and its coat becomes dull and unkempt. General fatigue, lethargy, and a belly that appears distended or uncomfortable are possible. In young indris, stunted growth may develop if infestation is long-standing or severe. In serious cases, dehydration and vomiting 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
Parasitism is caused by various gastrointestinal nematodes (roundworms) that colonize the indri's stomach or intestines. These parasites lay eggs that are shed in the faeces, which then contaminate the environment, food, or water. The indri becomes infected by unintentionally ingesting eggs or larvae present on vegetation, soil, or during grooming.
Young animals, debilitated or stressed individuals, and those living in enclosures or small habitats with high population density are at greater risk. Poor environmental hygiene, accumulation of faeces, unbalanced diet, or a weakened immune system also favour the establishment and multiplication of parasites. Captivity, by altering natural avoidance behaviours towards soiled areas, increases the risk of reinfection.
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 primarily on fecal analysis (coproscopic examination) to search for and identify parasite eggs or larvae. The veterinarian may supplement this examination with a general clinical observation of the animal, assessment of its weight and body condition, and possibly blood tests if the animal's general condition is concerning.
Treatment
Treatment involves administering appropriate antiparasitic medications, selected by the veterinarian based on the type of worms identified. Nutritional support and sometimes rehydration may be necessary if the animal is notably weakened. Follow-up after treatment, with a new fecal examination, allows verification of treatment effectiveness.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Regular cleaning of the environment and frequent removal of feces limit contamination. Regular veterinary monitoring with fecal examinations allows detection of infestation before clinical signs appear. Balanced, appropriate nutrition helps maintain good overall health and stronger natural resistance. In conservation programs or captive settings, rigorous sanitary management and preventive parasite control planned by a wildlife veterinarian are recommended.
Possible complications
A heavy untreated infestation can lead to anemia, severe general weakness, marked dehydration, and in young animals or those already fragile, a risk of death. Chronic parasitism can also make the animal more vulnerable to other infections.
When to see a veterinarian
Persistent diarrhea or abnormal stools for several days
Presence of visible worms in the feces
Unexplained weight loss or loss of appetite
Dull coat associated with general lethargy
Swollen belly or signs of abdominal discomfort
Any sign of marked weakness in a young indri
Prognosis
The prognosis is generally favorable when infestation is detected early and treated appropriately. It becomes more guarded in cases of high parasite burden, in young animals, or when parasitism is associated with other conditions or significant stress, as can occur in captive settings or during habitat disturbance.
Frequently asked questions
Can a wild indri have worms without being sick?
Yes, a low parasitic load is often well tolerated by a healthy wild animal and does not always cause visible signs.
Can this parasitism be transmitted to humans?
Gastrointestinal nematodes of the indri are generally specific to this species or closely related ones; the risk of transmission to humans is considered very low, but any handling of a wild animal must remain cautious and supervised.
How to detect parasitism in a captive indri? The detection of parasitism in a captive indri requires regular monitoring through several methods: **Clinical signs to observe:** - Weight loss or failure to gain weight - Dull or rough coat - Lethargy and reduced activity - Diarrhea or digestive disturbances - Anemia (pale mucous membranes) - Abdominal distension **Diagnostic procedures:** - Fecal examination: microscopic analysis of fresh feces to identify parasite eggs or cysts - Blood tests: to detect blood parasites and assess overall health status - Physical examination: checking skin, fur, and body condition **Prevention and management:** - Maintain strict hygiene in the enclosure - Provide regular veterinary check-ups - Ensure proper diet and nutrition to support immune function - Quarantine new arrivals before introduction - Regular fecal screening even in apparently healthy animals - Appropriate anthelmintic treatment if parasites are detected Given the specialized needs of indris, consultation with a veterinarian experienced in exotic primates or lemurs is essential for accurate diagnosis and treatment.
Regular examination of faeces by a veterinarian specializing in wildlife is the most reliable method, as clinical signs may be subtle at first.
Is antiparasitic treatment risky for this endangered species?
The choice of product and its administration must be made without fail by a veterinarian familiar with the specific requirements of the species, since indris are sensitive and fragile animals, especially in captivity.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
ESCCAP — European Scientific Counsel Companion Animal Parasites
Content reviewed by the TunisieVet editorial team · Updated 02 September 2026
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