Roundworms and hookworms

Directly through ingestion of eggs in feces, or larvae pass through placenta or milk

Damage to digestive tract and loss of nutrients; migrating roundworm larvae in people can affect young children and people with a weakened immune system; hookworms can cause skin lesions or infections in people with a weakened immune system

Tapeworms

Ingestion of secondary hosts, such as fleas or prey animals (for example, mice)

Loss of nutrients

Flukes or lungworms

Ingestion of secondary hosts found near water (for example, snails or tadpoles)

Damage to lungs, liver, or intestines

Intestinal protozoa (for example, coccidia or Toxoplasma)

Ingestion of eggs in feces or infective cysts in prey animals

Gastrointestinal damage in cats; infection of pregnant women (toxoplasmosis) can potentially result in serious injury to fetus, young children, or immunocompromised individuals

Heartworm

Passed by infected mosquitoes, especially in southeastern US

Damage to blood vessels of the lungs, the lungs themselves, and the heart

Fleas, ticks, and mites

Passed directly outdoors or from other infected cats in household (for example, mother to kitten)

Skin damage, itching, secondary skin infection, ear infection (ear mites), flea allergy, tapeworms (fleas), and secondary bloodborne diseases (for example, infectious anemia transmitted by fleas or ticks)

Cuterebra (fly larvae)

Contact with fly larvae near rodent or rabbit burrows

Unsightly lumps on head or neck; secondary infections under the skin