Healthy Pets Healthy Families - Zoonoses & Parasite Prevention

Zoonotic Diseases & Parasite Prevention

What are zoonotic diseases?

Zoonotic diseases (zoonoses) are illnesses that can be passed between animals and people, including wildlife. When animals get sick, people can sometimes become infected, too.

Over half of known human infectious diseases come from animals. In LA County, important examples include rabies, West Nile virus, leptospirosis, flea-borne typhus, and intestinal parasites (e.g., roundworms, hookworms, tapeworms).

Zoonotic diseases and pets
How zoonoses can spread between animals & people
  • Contact with animal feces or urine
  • Bites from infected animals
  • Breathing droplets when animals cough, sneeze, or bark
  • Direct physical contact
  • Bites from infected insects/arthropods (vectors) like fleas, ticks, or mosquitoes
Facts in Los Angeles County
Human behaviors affect risk
Rabies
Mosquito-borne diseases
  • West Nile virus (WNV) and canine heartworm are spread by mosquitoes.
  • WNV occurs in LA County every year and can infect people, birds, and horses.
  • Heartworm occurs in some local dogs and cats; human infection is rare.
Flea-borne typhus
  • Transmitted by fleas from opossums or cats; animals often show no symptoms while people can become ill.
Gastrointestinal diseases
  • Pet intestinal parasites (e.g., roundworm) can cause serious illness in people, especially children.
  • Salmonella is common in reptiles and can cause severe GI illness in people.
What you can do to protect your family & pets
  • Practice good hygiene: Wash hands after touching animals—especially reptiles.
  • Keep vaccines up to date for dogs and cats (even indoor pets). Curious pets may contact sick or dead wildlife (e.g., bats).
  • Ask your veterinarian about regular deworming and parasite prevention.
  • Don’t leave food or water outdoors—this attracts wildlife and pests.
  • Prevent mosquito bites: Empty standing water twice weekly; use screens and protective clothing, especially at dusk/dawn.
  • Keep pets on flea/tick control so pests are less likely to jump onto people.
What Public Health is doing

We work with partners to ensure pets and owners can access the medications and services needed to prevent zoonotic diseases and parasites.

Pet expos & services: With local partners, we host/attend community events that offer low-cost or free preventive services such as deworming, flea/tick prevention, spay/neuter, vaccinations, and more—plus connections to ongoing care.

Last updated: September 2025