Parasitic Stomach Worm (Ollulanis) Infection Cats


PetMD Editorial

Updated Aug. 24, 2022

Ollulanis Tricuspis Infection in Cats

Ollulanis infection is a parasitic worm infection that occurs mainly in cats. It is caused by Ollulanus tricuspis, which spreads in the environment through the vomit of other infected hosts and goes on to take up residence in the stomach lining. Ollulanus tricuspis is a small nematode parasite which lays its eggs in the mucosal lining of the stomach wall, where it irritates the stomach, inducing vomiting in the cat and further spreading into the environment and into other hosts. These infections are commonly seen in colonies of cats, as well as in stray cats in urban areas that are heavily populated with cats and in cats that are frequently outdoors. Even captive cheetahs, lions, and tigers are susceptible to this infection.

The adult worms coil into the stomach's inner lining, causing ulcers, inflammation, and fibrosis (abnormal development of fibrous tissue).

Symptoms and Types

  • Vomiting (chronic)
  • Poor appetite
  • Weight loss
  • Death due to chronic stomach infection


Ollulanus tricuspis worm infection is usually transmitted through ingesting the vomit contents from an infected host.


You will need to give a thorough history of your cat’s health, including background medical history, details of the onset of symptoms, your cat's usual routine, and any events that may have led to your cat's condition. After taking a complete history, your veterinarian will conduct a complete physical examination, including a complete blood profile, chemical blood profile, a complete blood count, and a urinalysis. The results of these laboratory tests may reveal dehydration due to vomiting and diarrhea.

Your veterinarian will also examine your cat's feces and vomit contents for evidence of parasites. In this case, the ollulanis worm is digested if it enters into the digestive tract, so an analysis of the vomit is the only way your veterinarian can make a more conclusive diagnosis. Unless you are able to take a fresh sample of your cat's vomit with you to the veterinary clinic, your veterinarian will need to induce vomiting by giving your cat vomit inducing medications, or the doctor may decide to perform a stomach lavage, which gathers the contents of the stomach by washing them out.

An abdominal ultrasound may also reveal a thickening of the stomach wall due to chronic irritation and infection.


Drugs to kill parasites residing in the stomach may be used, but often, complete removal is not achieved on the initial treatment. Symptoms may improve after the first treatment. You will need to revisit your veterinarian to retest for the presence of the stomach worm.

Living and Management

Watch your cat for vomiting or other symptoms which might show recurrence and call your veterinarian to schedule a second round of treatment. If your cat is vomiting, immediately remove the vomit contents, using strong cleaners to clean the area. Keep a sample of the vomit, if possible, to give to your veterinarian. The stomach worm can live for up to 12 days in the vomit content, so it is not necessary to do anything special with the saved contents immediately. If there are other cats in the home, do not allow them to go near the vomit contents.

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