Home » Diseases » In cats » Baylisascaris (Parasitic Infection with the Raccoon Roundworm, Raccoon Disease)

Baylisascaris (Parasitic Infection with the Raccoon Roundworm, Raccoon Disease) in cats

Occurrence: common
Location of illness: Abdomen/pelvis

Author: Dr. med. vet. Gisa Löwe | Last modified: 03.12.2025

When to visit the vet?

Urgent see a veterinarian within 24 hours

If the condition worsens / symptoms persist, consult a veterinarian.

An interesting overview of gastrointestinalGastrointestinal refers to the gastrointestinal tract, a system that extends from the oral cavity to the anus and is responsible for the digestion of food and the absorption of nutrients. problems in cats, supplemented by information on the intestinalIntestinal refers to the intestine, the part of the digestive tract that extends from the stomach to the anus. Intestinal diseases affect the small and/or large intestine. microbiome and the importance of probiotics, can be found here: https://petsvetcheck.de/fachbeitrag/magen-darm-probleme-bei-katzen/

Baylisascaris is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. infection caused by the raccoon roundworm Baylisascaris procyonis, which can cause neurological symptoms in cats if they become infected with the parasite’s eggs.

The most important facts at a glance

Baylisascaris is a parasitic infection in cats caused by the roundworm Baylisascaris procyonis, originally from raccoons. Cats become infected by ingesting the resilient eggs of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans., which can be found in areas with raccoon feces. Since cats are not suitable hosts, the larvae migrate in their tissues, causing severe inflammation, especially in the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior.. This leads to neurological symptoms such as uncoordinated gait, difficulty swallowing, Convulsions, and general weakness.

DiagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is often difficult and requires a thorough medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits. and special tests, as symptoms are non-specific. Imaging techniques and antibodyAn antibody is a protein produced by the immune system to recognize and bind specific antigens. By binding to the antigen, antibodies can help destroy or neutralize it. tests can provide clues, but a definitive diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is usually made post-mortemPost-mortem, also called postmortal, means "after Death." In veterinary medicine, it refers to examinations or autopsies performed to determine the cause of Death or diseases after an animal's Death.. Treatment focuses on symptom relief, as there are no specific medications. AntiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth. and anti-inflammatory drugsAnti-inflammatory drugs are medications that reduce inflammation. They can be divided into nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids and are used in dogs and cats to reduce Inflammatory conditions and Pain. can be used, but their effectiveness is limited. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is often poor, as the damage caused by the larvae can be irreversible.

Preventive measures are crucial and include limiting cats’ outdoor access, securing trash cans to keep raccoons away, and regular deworming programs. Research aims to develop better diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment methods, as well as to explore preventive measures such as potential vaccines, to minimize the risk of infections.

Causes

Baylisascaris procyonis is a roundworm that primarily lives in the small intestineThe intestine is the medical term for the gut, including the small intestine (intestinum tenue) and the large intestine (intestinum crassum). It plays a central role in the digestion and absorption of nutrients. of raccoons. Raccoons are the primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. hosts in which the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. can complete its life cycle. AdultThe term "adult" refers to an individual who has reached full physical development and is considered an adult. In veterinary medicine, this term is used to describe animals that have completed growth and are of reproductive age. worms lay eggs, which are then excreted in the raccoon’s feces. These eggs are extremely resilient and can survive in the environment for years under favorable conditions.

The infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. in other animals, including cats, occurs when they accidentally ingest the infectiousInfectious describes the ability of a pathogen to be transmitted from one individual to another and trigger an infection. It also refers to diseases caused by such pathogens. eggs. This can happen if cats roam in areas contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. with raccoon feces, or if they eat infected prey animals that have ingested the eggs. Since cats are not suitable hosts for the complete development of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans., the larvae migrate in the cat’s tissues, which can lead to severe inflammation and tissue damage.

The migrationMigration refers to the movement or migration of cells or organisms from one place to another. In veterinary medicine, this can include the movement of parasites within the body of dogs and cats. of the larvae can particularly affect the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior., leading to neurological disorders. This migrationMigration refers to the movement or migration of cells or organisms from one place to another. In veterinary medicine, this can include the movement of parasites within the body of dogs and cats. is called “Larva migrans” and is the main reason for the severe symptoms observed in infected cats.

Symptoms

Very common symptoms:

Common symptoms:

The symptoms of Baylis-Ascariasis in cats occur mainly due to the migrationMigration refers to the movement or migration of cells or organisms from one place to another. In veterinary medicine, this can include the movement of parasites within the body of dogs and cats. of the larvae through the tissue. The most common symptoms include neurological signs such as ataxia (Coordination disorders), Krampfanfälle, and unusual Behavioral changes. Blindness can also occur if the larvae migrate to the eyes.

In addition to neurological symptoms, cats may also suffer from general weakness, Weight loss, and Vomiting. Symptoms can appear suddenly and worsen rapidly, requiring quick diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment.

Diagnosis

The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of Baylisascaris in cats can be challenging because symptoms are non-specific, and many other diseases can cause similar symptoms. A thorough medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits., including information about the cat’s habitat and possible contact with raccoons, is crucial.

Laboratory tests can be helpful to rule out other causes for the symptoms. A definitive diagnosis of Baylisascaris can be made by identifying the larvae in the tissue, which is usually performed post-mortemPost-mortem, also called postmortal, means "after Death." In veterinary medicine, it refers to examinations or autopsies performed to determine the cause of Death or diseases after an animal's Death.. In some cases, imaging techniques such as MRI or CT scans can provide clues to the presence of larvae in the brain. Confirmatory tests for specific antibodies against Baylisascaris procyonis in the blood or cerebrospinal fluid (CSF)Cerebrospinal fluid (CSF), also known as Liquor cerebrospinalis or brain-spinal fluid, surrounds the brain and spinal cord. It serves as protection and for the nutrient supply of the central nervous system as well as for the disposal of metabolic products. can also be performed.

Therapy

The treatment of Baylisascaris in cats is difficult because there are no specific medications that can effectively kill the larvae once they have migrated into the tissues. Therefore, therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. mainly focuses on alleviating symptoms and supporting the affected animal.

AntiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth. such as albendazole or ivermectin can be administered to reduce the number of migrating larvae, although their effectiveness is variable. Additionally, anti-inflammatory drugsAnti-inflammatory drugs are medications that reduce inflammation. They can be divided into nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids and are used in dogs and cats to reduce Inflammatory conditions and Pain. can be used to minimize the inflammatory response in the central nervous systemThe CNS (central nervous system) consists of the brain and spinal cord. It is responsible for processing information and controls most functions of the body and behavior.. SupportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. measures such as fluid therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. and nutritional support are also important to maintain the cat’s overall health.

Prognosis and follow-up care

The prognosis for cats with Baylisascaris is generally poor. The neurological damage caused by larval migrationMigration refers to the movement or migration of cells or organisms from one place to another. In veterinary medicine, this can include the movement of parasites within the body of dogs and cats. is often irreversible, and many cats do not fully recover. The course of the disease can be rapid and progressiveProgressive describes a condition or disease that worsens over time. This term is often used to characterize the course of an illness that causes increasingly severe symptoms or damage., often leading to a fatal outcome.

Early diagnosis and treatment can delay the progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of symptoms, but complete recovery is rare. The quality of life of the affected cat should be considered when deciding on the continuation of treatment.

Prevention

To minimize the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. with Baylisascaris procyonis, the raccoon roundworm, in cats, pet owners should ensure their cats are kept indoors as much as possible or supervise their outdoor access. This reduces the likelihood of the cat coming into contact with potentially contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. soil or raccoon feces.

Another important preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. approach is controlling the raccoon populationIn veterinary medicine, the term population refers to a group of animals of a particular species living in a specific geographic area or environment. in the area. Pet owners can take steps to keep raccoons off their property by securely closing trash cans and not leaving food sources outdoors that could attract raccoons.

Regular deworming programs for cats are also essential to reduce the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. with various parasites. Pet owners should discuss appropriate deworming plans with their veterinarian, tailored to their cat’s specific needs.

Additionally, owners should ensure hygiene in the cat household. This includes regular cleaning of litter boxes and immediate disposal of cat feces to reduce the likelihood of parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. transmission. Through these measures, the risk of Baylisascaris in cats can be significantly reduced.

Outlook on current research

Baylisascaris, caused by the roundworm Baylisascaris procyonis, is a zoonotic infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. primarily found in raccoons. However, scientific interest is increasingly drawn to its potential threat to pets like cats and their owners. While previous studies mainly focused on the epidemiology and life cycle of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. in its natural host, the raccoon, current research is increasingly directed towards transmission routes and potential health risks for other animals and humans.

A significant aspect of current research is the investigation into the transmissibility of this parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. to domestic cats and the resulting clinical symptoms. Researchers are working to map the prevalence of Baylisascaris infections in various geographical regions to better understand the spread. Additionally, studies are examining how environmental factors and human activities affect its distribution and infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. rate.

Another important research area is the development of diagnostic tests specifically suited for detecting this infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. in cats. Since symptoms are often non-specific and difficult to distinguish, it is crucial to develop reliable diagnostic methods that enable early detection. Researchers are working to improve molecular techniques to quickly and precisely identify the genetic material of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans..

In parallel, intensive research is being conducted on therapeutic approaches. While effective treatments already exist for other roundworms, research is exploring how these can be applied to Baylisascaris infections in cats. The development of medications that specifically target this parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. is a primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. goal to protect pet health and prevent potential transmission to humans.

Long-term research projects aim to develop preventive measures to minimize the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. in cats and humans. This also includes the investigation of vaccines that could prevent infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. Research in this field is still in its early stages but shows promising approaches.

Frequently asked questions (FAQs)

What is Baylis-Ascariasis? Baylis-Ascariasis is a parasiticParasitic refers to diseases or conditions caused by parasites. Parasitic infections can affect the digestive tract, skin, and other organ systems. infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. caused by the roundworm Baylisascaris procyonis, which is mainly found in raccoons. However, the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. can also infect other animals and humans.
Can cats get Baylis-Ascariasis? Yes, cats can become infected with Baylisascaris procyonis, especially if they have access to environments where raccoons live or have left their fecal traces.
How do cats get infected with Baylisascaris? Cats can become infected by ingesting contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. soil, water, or prey that are infected with the eggs of the parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans..
What are the symptoms in cats? The symptoms can vary but include neurological signs, digestive problems, and in severe cases, Krampfanfälle and ParalysisParalysis is the complete loss of muscle activity in one or more areas of the body, which can lead to immobility and loss of sensation. Paralysis can be caused by injuries, illnesses, or disorders of the nervous system..
How can Baylis-Ascariasis be diagnosed in cats? The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is usually made through a combination of clinical symptoms, medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits., and special laboratory tests that can detect the presence of parasiteA parasite is an organism that lives on or in another living being (the host) and feeds at its expense. Parasites can cause a variety of diseases in animals and humans. DNADNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, function, and reproduction of all known living organisms and many viruses. It is located in the cells of an organism and contains the information for heredity..
Is there a treatment for Baylis-Ascariasis in cats? Yes, there are antiparasiticsAntiparasitics are medications or substances used to treat parasitic infestations, such as worms, protozoa, and ectoparasites. They work by killing the parasites or inhibiting their growth. that can be used for treatment. However, the effectiveness may vary depending on the stage of the disease. Early treatment is crucial.
How can an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. be prevented in cats? An infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. can be prevented by avoiding contact with raccoons and their feces. Regular deworming and hygiene are also important preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. measures.
Is Baylis-Ascariasis transmissible to humans? Yes, humans can become infected through direct contact with contaminatedContaminated describes something that has been polluted by harmful microorganisms, chemicals, or other dangerous substances. In veterinary medicine, this can affect food, water, toys, or the environment. materials. The infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. can cause severe neurological damage.
What measures should be taken if an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. is suspected? If an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. is suspected, a veterinarian should be consulted immediately to initiate appropriate tests and treatments. Precautions to protect human health are also important.
Are there vaccines against Baylis-Ascariasis? Currently, there are no vaccines against Baylis-Ascariasis. However, research in this area is ongoing to develop effective preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring..