Learning that your dog has tested positive for intestinal parasites can cause anxiety about catching worms from your pet. This concern is valid, as some canine parasites are zoonotic, meaning they can be transmitted to people. The risk of transmission is generally low and manageable with proper precautions. The most effective way to protect yourself is through accurate information, targeted hygiene, and consultation with a human medical professional for any suspected infection, not self-medication.
Which Dog Worms Can Affect Humans
The primary concern for transmission from dogs to humans centers on two specific types of intestinal parasites: roundworms and hookworms. Canine roundworms (Toxocara canis) are transmitted when microscopic eggs shed in dog feces are accidentally ingested, often via contact with contaminated soil or surfaces. The eggs must mature in the environment for approximately two weeks to become infectious, which is why contaminated areas like parks and sandboxes pose a risk.
Hookworms (Ancylostoma braziliense) use a different route of infection, with the larvae penetrating human skin directly. These larvae hatch from eggs deposited in the environment and live in warm, moist, sandy soil. Walking barefoot in contaminated areas is the most common way for the larvae to enter the body. While other worms exist, such as whipworm and heartworm, they are not considered significant direct zoonotic risks.
What Human Symptoms Look Like
In people, roundworm larvae cause Visceral Larva Migrans (VLM) as they travel through internal organs, or Ocular Larva Migrans (OLM) if they migrate to the eye. Most infections are asymptomatic, meaning they produce no noticeable symptoms, but when signs do appear, they are often vague. These non-specific symptoms can include fever, fatigue, an unexplained cough, or abdominal discomfort.
Ocular Larva Migrans is a more serious presentation that can cause inflammation and vision problems, potentially leading to permanent vision loss if the larva settles in the retina. Hookworm larvae usually cause a skin condition known as Cutaneous Larva Migrans (CLM), or “creeping eruption.” The larvae migrate just beneath the skin’s surface, creating intensely itchy, raised, red, serpentine-like tracks that advance a few centimeters each day.
Humans are considered “dead-end hosts” for these parasites, meaning the larvae cannot complete their life cycle to become adult worms in the human body. If you develop a persistent, unexplained rash, sudden vision changes, or prolonged, non-specific symptoms, you should consult a doctor.
Why Self-Medication is Not Recommended
Self-medication for a suspected parasitic infection is not recommended, as it carries significant risks and is unlikely to be effective. Antiparasitic medications are prescription-only drugs, and the specific treatment required depends entirely on the type of parasite involved. Treating a hookworm infection requires a different drug or dosage than treating a roundworm infection, and a non-specific remedy may fail to address the actual problem.
Taking a drug without a proper medical diagnosis may also mask symptoms, making it more difficult for a physician to diagnose a serious condition later. Furthermore, using drugs intended for animals is dangerous because veterinary medications are formulated for different metabolic systems and can be toxic to humans. Attempting to use over-the-counter “cleanses” or herbal remedies is also not recommended. A physician will confirm a parasitic infection through specific tests, such as a stool sample or blood test, before prescribing the correct course of treatment.
Reducing Risk Through Hygiene and Pet Care
Focusing on preventative hygiene and pet care is the most effective and actionable step you can take to manage your risk. Strict handwashing is the single most important defense, especially after handling pet waste, gardening, or any contact with soil. Using warm water and soap for a minimum of 20 seconds helps remove any microscopic eggs that may have been transferred to your hands.
There are several key actions to reduce environmental contamination:
- Promptly remove and dispose of all dog feces from your yard daily to prevent eggs from maturing into the infectious stage.
- Always wear shoes outdoors, particularly in areas where dogs may have defecated, since hookworm larvae can penetrate the skin.
- Maintain your dog on a consistent, veterinarian-prescribed deworming schedule.
- Ensure your dog is on a consistent flea control schedule, as this breaks the life cycle of the parasites and greatly reduces the risk of environmental contamination.