Similar to dogs and cats, ferrets can be infected with internal or external parasites. The most common ones are discussed below.

Internal Parasites
Protozoa is a one-cell organ parasite that can cause disease in ferrets. Some of the most critical of these are:

Toxoplasmosis:
Infects the brain.

Symptoms: Anemia, eye lesion, inflammation of liver, blindness, CNS sing, respiratory disease, and diarrhea.

Diagnosis: Laboratory test on blood.

Treatment: Antibiotic and supportive therapy.

Prevention: Do not expose the ferret to infected animals.

Coccidiosis:
Usually infects young ferrets.

Symptoms: Bloody diarrhea.

Diagnosis: Laboratory test on fecal.

Treatment: Antibiotics and supportive therapy.

Cryptosporidiosis:
Cause disease in immunosuppressive ferrets and can infect immunosuppressive people.

Symptoms: Diarrhea, fever, abdominal pain, constipation, and weight loss.

Diagnosis: Laboratory test on fecal sample.

Treatment: Is not effective.

Prevention: Wash the contaminated area with 10% ammonia.

Giardiasis:
Infects ferrets.

Symptoms: Soft stool, listlessness and weight loss.

Diagnosis: Fecal test

Treatment: Antibiotics and supportive therapy.

Prevention: Clean the environment thoroughly and disinfect with 5% pine tar or 1% house bleach.

Helminthes:
Ferrets are susceptible to all dogs and cat parasite including heartworm and to some rabbit, mice and other rodent parasites. The most important ones are discussed below.

Round Worms:
Infect ferrets' intestine, lung, and other organs. The parasite egg can transmit to the owner. Children are in high risk.

Prevention: Fecal worm check is recommended annually and treats the infected ferret. If the ferret is positive, dogs and cats in the same environment should be checked and wormed. Children should consult their physician.

Heartworms:
Infect ferrets.

Symptoms: Vague with anorexia and coughing.

Diagnosis: SNAPS test and x-ray.

Treatment: In early stage is possible.

Prevention: Heartworm preventive medication (at this point there are none that are label approved). Consult with your vet for a possible preventative medicine.

External Parasites

Fleas:
One of the most important external parasites in ferrets. It transmit from bacillus to tape worm to ferrets.

Symptoms: General inflammation from the flea bites, heavy scratching, and anemia.

Diagnosis: Visual.

Treatment: Treat the symptoms and prevent reinfestation.

Prevention: Be careful not to use any product with out consulting your veterinarian.

Ear Mange:
infects ferrets external ear. If not treated will infect internal ear and may rupture the tympanic membrane.

Symptoms: Head shaking and rubbing.

Diagnosis: Take a swab from the ear and examine under microscope.

Treatment: Possible

Foot Mange:
The infection starts in the foot caused by mange and is highly contagious to people.

Symptoms: Yellow incrustation covers the foot.

Diagnosis: Examination of skin scraping under microscope.

Treatment: Clean or destroy all the bedding. Treatment is hard but possible.