Veterinary advice should be sought from your local veterinarian before applying any treatment or vaccine. Not sure who to use? Look up veterinarians who specialize in poultry using our directory listing. Find me a Vet


Other Names: Proventricular Tetrameriasis, Tetrameriosis

Tetrameriasis is a parasitic infection of poultry caused by Tetrameres spp (T. americana or T. fissispina) roundworms. Tetrameres spp are small parasitic roundworms which invade the proventriculus of chickens, turkeys, pigeons, guinea fowls, ducks, pheasants, and quails. There are two species which infect poultry: T. americana and T. fissispina.

Adult female Tetrameres spp worms embed themselves into the glands or lining of the proventriculus, which induces nodules that can grow so large that they compress the glands and can cause them to atrophy. The mucosa of the proventriculus becomes irritated and inflamed from Tetrameres spp continuously feeding. This can result in the accumulation of undigested food in the proventriculus, which can flow back to the esophagus and the crop that become obliterated.

Life Cycle

Tetrameres spp have an indirect life cycle. Chickens become infected through ingestion of an intermediate host, which are grasshoppers, cockroaches, earthworms, and water fleas. Adult female Tetrameres worms lay embryonated eggs in the host's gut that are passed in their droppings. Intermediate hosts ingest the eggs from the environment, which release the larvae a few hours later. These larvae complete development to infective L3 larvae in about 7 weeks and become encysted in the body of the intermediate host. The prepatent period (time between infection and first eggs shed) of Tetrameres worms is 7-8 weeks, depending on worm species and host.

Tetrameriasis Diagnosis

Tetrameriasis is diagnosed based on detection of Tetrameres eggs in the feces via a fecal test.

Tetrameriasis Treatment

Anthelmintics effective against Tetrameres worms include benzimidazoles (albendazole, fenbendazole, flubendazole, mebendazole, oxfendazole), levamisole, ivermectin, and piperazine.

Clinical Signs

Delayed crop emptying
Green droppings
Weight loss


  • Fecal examination
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
AnthelminticsBenzimidazoles (albendazole, fenbendazole, flubendazole, mebendazole, oxfendazole), levamisole, ivermectin, and piperazine.



Regularly conduct fecal tests and/or scheduled deworming program

Scientific References

Risk Factors

  • Free range flocks
  • Not conducting annual fecal testing
  • Allowing birds access to grasshoppers, cockroaches, earthworms, and water fleas.