Gnathostoma
Holly Frisby, DVM
Veterinary Services Department, Drs. Foster & Smith, Inc.
Does Gnathostoma have a simple life cycle?
The answer is a definitive 'NO.' The eggs exit the body in the feces, but they need to be in water to develop into larvae. The egg hatches and the larva swims about until an unsuspecting small water flea eats it. The larva develops in the water flea that is then eaten by a fish. Hang on, we are not even close to done. The larva develops into the final immature form in the fish. The fish is eaten by something bigger, and the larva is released and can migrate through that animal. This can go on and on. Finally, a dog eats an animal containing the larva, and the larva is freed again. But wait, it does not stay in the stomach, but goes through the stomach wall and migrates to the liver, muscles, connective tissues. After three months, the larva winds up back in the stomach where as an adult it attaches itself to the stomach wall.
What kind of damage does Gnathostoma cause?
During the migration of the mature larvae through the carnivore's tissues, extensive damage can occur. Nodules develop around the adult worm in the stomach. If a nodule becomes large, it can break and stomach contents can leak into the abdominal cavity. This causes a severe inflammation called peritonitis, which can be fatal.
What is the treatment for Gnathostoma in animals?
The treatment for Gnathostoma is unknown, although some reports suggest albendazole may be effective.
How are humans affected by Gnathostoma?
The migrating larvae in humans are found under the skin where they create tunnels that develop into abscesses. The larvae may also migrate through the eye or brain causing severe damage.
References
Georgi, J. R., and Georgi, M. E. Canine Clinical Parasitology. Lea & Febiger. Philadelphia, PA; 1992.
