Gastrointestinal parasitism in African savanna elephants (roundworms)

What is it?

Gastrointestinal parasitism caused by roundworms (nematodes) is very common in African savanna elephants, whether they live in reserves, national parks, or in captivity. These parasites live in the intestine and sometimes the stomach. They are almost always present in small numbers in healthy elephants without causing problems. Issues arise when their numbers become too high, particularly in young animals, weakened or stressed individuals, or when environmental conditions favor their multiplication.

Commonly observed signs

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

Causes and risk factors

Several families of gastrointestinal nematodes can affect elephants, including digestive strongyles similar to those found in large herbivores and ascarids specific to elephantids. Adult worms lay eggs that are shed in the feces; these eggs develop into an infective stage in the environment and are then reingested by the animal while grazing or drinking contaminated water, completing the cycle.

Young age is a major risk factor, as immunity is not yet mature. Overcrowding in limited space (park, enclosure) increases parasite concentration in the environment. Contaminated grazing areas or water sources fouled by feces encourage reinfestation. Stress, unbalanced nutrition, concurrent illness, or immunosuppression increase susceptibility. The rainy season promotes larval survival in the environment, thereby increasing parasitic pressure.

Transmission

Transmission occurs by indirect fecal-oral route: worm eggs shed in the feces develop in the external environment (soil, vegetation, water) until they become infective, then are ingested by the elephant while grazing or drinking. There is no direct transmission from one animal to another without passage through the environment.

Diagnosis and care

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

Treatment

Treatment, determined by the veterinarian based on test results, uses antiparasitic drugs from the anthelmintic family suited to the species. The choice of drug and need for treatment depend on the intensity of infestation observed, as indiscriminate treatment promotes the development of resistance.

Prevention

Possible complications

Severe untreated infestation can lead to significant weight loss, anemia, general weakness making the animal more vulnerable to other diseases, and in young animals, permanent growth retardation. In rare extreme cases, intestinal obstruction from a mass of worms has been reported in heavily infested young animals.

When to see a veterinarian

Prognosis

The prognosis is generally good when the infestation is detected and treated early. In a healthy adult, a moderate parasite burden is well tolerated. The prognosis is more guarded in young animals or those already weakened by another disease, where a heavy infestation can have lasting effects on growth and overall condition.

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