Gastrointestinal parasitism in the hippopotamus (roundworms)

What is it?

Gastrointestinal parasitism in the hippopotamus refers to infestations by roundworms (nematodes) that live in the animal's stomach or intestines. These parasites are common in hippopotamuses living both in the wild and in captivity, as the animal spends much of its time in water and grazes on wetland areas that favour larval survival. Most healthy adult hippopotamuses harbour some level of parasites without showing significant clinical signs. Problems typically arise when the parasite burden becomes too high, particularly in young animals, weak or stressed individuals.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

Several species of roundworms (nematodes) can parasitise the hippopotamus's digestive tract, notably gastrointestinal strongyles similar to those found in other large herbivores. These worms lay eggs that are shed in faeces and develop into infective larvae in the moist environment typical of hippopotamus habitat. The animal becomes reinfected by grazing on grass contaminated with these larvae or by moving through water polluted by faecal matter.

Young animals, being less immune, are more vulnerable than adults. Overcrowding in an enclosure or limited water point promotes accumulation of parasites in the environment. Stress, concurrent disease, unbalanced diet or inadequate sanitation of the enclosure increase the risk of significant infestation. In zoos, insufficient hygiene of the pool and grazing areas constitutes a major risk factor.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Treatment involves administering broad-spectrum antiparasitic drugs (dewormers) under veterinary supervision. The choice of medication and treatment frequency depend on the situation, level of infestation, and test results. Supportive measures such as enhanced feeding and environmental improvements may accompany treatment in more severe cases.

Prevention

Possible complications

Severe untreated infestation can lead to marked weight loss, anemia, general weakness, and increased susceptibility to other diseases. In young animals, this may compromise normal growth. In rare extreme cases, very high parasite burden combined with other stressors can contribute to death, particularly in already weakened individuals.

When to see a veterinarian

Prognosis

The outlook is generally favorable when infestation is detected early and treated appropriately. Most hippopotamuses recover well after antiparasitic treatment combined with improved husbandry conditions. The outlook becomes more guarded in young animals or those already weakened by longstanding heavy infestation.

Frequently asked questions

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 30 August 2026