Baylisascaris is a type of roundworm that is found in intestines of most raccoons. The worm is harmless for raccoons but it is a serious threat for 50 other species, dogs and humans included!
Most commonly called "raccoon disease" because of its prevalence in the raccoon population, baylisascariasis comes from contact with raccoon feces, and from ingesting animal tissue that is infected with the Baylisascaris procyonis parasite.
Raccoons are primary hosts of these worms as they are not adversely affected by this worm, making them ideal hosts and disseminators of the parasite.
Seconday hosts of the parasite are birds, rabbits, rodents and some other animals which come in contact with this parasite through feces, or soil that has been used by an infected raccoon. The larva is known to migrate to the brain, where it affects the nervous system. The affected animal becomes weak and an easy catch for predator animals (dogs). Ingestion of affected tissues by dogs transmits the worm into their body.
The condition is treatable in adult dogs but almost always fatal for puppies. Since the condition affects nervous system, symptoms may resemble in that of rabies. If the dog is suspected to have rabies, it is better to have it checked for raccoon disease first.
Baylisascariasis is of two types, intestinal infection and visceral disease. When the roundworm eggs are ingested, they migrate to the intestine, develop further and then migrate to the viscera (the organs that occupy the abdominal cavities), the nervous system, or the eye. These migrations are known as larval migrans; visceral larval migrans (VLM); neural larval migrans (NLM); and ocular larval migrans (OLM).
Adult dogs are most affected by intestinal infection while the condition affects internal organs specially the brain and spinal cord of puppies.
Mild symptoms of neurological disease may be shown otherwise there are no outward symptoms associated with early onset of disease.
Signs of neurological disease (NLM) include:
Unsteady walking/loss of coordination or muscle control (ataxia)
Difficulty eating/swallowing (dysphagia)
Lethargy, lying down excessively (recumbency)
Confusion, lack of attention
Visceral infection may cause symptoms of liver and/or lung diseases while infection of the eye may not be apparent until the dog has lost its vision.