Baylisascaris procyonis

Test code: X0019 - Ultrasensitive qualitative detection of Baylisascaris procyonis by real time PCR

Baylisascaris procyonis infection has recently been recognized as an important and widespread emerging helminthic infection of both animals and humans. Raccoons are thought to be the most favorable host for this roundworm; reported infection rates are as high as 70% in adult raccoons and can exceed 90% in juvenile raccoons. Due to the close interaction of raccoons with human populations and pets, this parasite has increasingly been recognized as a cause of severe human disease.

When raccoons ingest the eggs of this parasite the larvae hatch, enter the wall of the small intestine and subsequently develop into adult worms in the small bowel. These adult worms shed eggs into the raccoon’s bowel. Although raccoons are not significantly affected by these parasites, ingestion of the eggs by other suboptimal host mammals (including rodents, birds, dogs and other domestic mammals) results in extraintestinal migration of larvae, and notably invasion of the brain. The migration of helminth larvae through tissue in suboptimal hosts is termed larva migrans and may affect the viscera (visceral larva migrans [VLM]), the eye (ocular larva migrans [OLM]), or the nervous system (neural larva migrans [NLM].

B. procyonis larvae have been found in more than 90 species of wild and domestic mammals and birds, including dogs, chickens, pheasants, quail, guinea pigs, domestic rabbits, rodents, porcupines, chinchillas, prairie dogs, woodchucks, emus, foxes, weasels and primates. Outbreaks of B. procyonis infestation have been reported on farms, in zoos, among pets and in research animal colonies.

The risk of human infestation by this parasite has risen alarmingly due to pets’ contact with raccoon feces. Studies have shown that a single adult female worm can produce hundreds of thousands of eggs per day, and an infected raccoon may shed as many as 45 million eggs daily (Jacobson et al., 1982; Kazacos and Boyce, 1989). These eggs can remain viable in the environment for years. Accidental ingestion of the eggs by humans via contact with infected domestic animals can lead to severe human infection and death.

In the past, B. procyonis infection was diagnosed by morphologic identification of larvae in tissue sections. However, morphologic identification is often difficult and unreliable because a number of possible larval nematodes share very similar morphology, including Toxocara canis, T. cati, Ascaris lumbricoides, and species of Gnathastoma, Angiostrongylus and Ancylostoma, as well as larval cestode infections such as cysticercosis and echinococcosis. While serologic testing has been used in some cases as supportive diagnostic evidence, commercial serologic tests are not available. Presumptive diagnosis has often been made on the basis of clinical data (meningoencephalitis, diffuse unilateral subacute neuroretinitis [DUSN], pseudotumor), epidemiologic data (raccoon exposure), radiologic data (white matter disease), and blood and CNS eosinophilia.

However, molecular detection techniques are now available to rapidly, sensitively and specifically detect B. procyonis.  With this more advanced approach, preventive screening and environmental surveys are possible, enabling identification of animal carriers and even contaminated soils.

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of Baylisascaris infection
• Ensure that flocks are free of Baylisascaris
• Early prevention of spread of Baylisascaris among birds, and between birds and other animals
• Minimize human exposure to Baylisascaris

References:
Jacobson, J.E., Kazacos, K.R., and Montague, F.H. (1982) Prevalence of eggs of Baylisascaris procyonis (Nematoda:Ascaroidea) in raccoon scats from an urban and a rural community. J Wildl. Dis. 18:461-464.
Kazacos, K.R. and Boyce, W.M. (1989) Baylisascaris larva migrans. J. Am. Vet. Med. Assoc. 195:894-903.

Specimen requirement: 0.2 ml feces, or cloacal swab, or 0.5 ml soil, or 0.2 ml tissue.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected