What treatment is recommended for a human potentially exposed to parasitic worms from their dog?

Empiric Treatment for Potential Canine Parasitic Exposure

For a patient potentially exposed to dog parasites, empiric treatment with a single dose of albendazole 400 mg is recommended, as this covers the most common zoonotic helminths transmitted from dogs to humans, including roundworms (Toxocara), hookworms (Ancylostoma), and other soil-transmitted helminths. 1, 2

Rationale for Empiric Treatment

Why Treatment Without Confirmed Diagnosis

• Direct exposure to a parasitized dog (evidenced by visible worms in vomit) represents significant risk for zoonotic transmission 1
• Standard stool microscopy has poor sensitivity and may miss infections, particularly in early stages before patent infection develops 1
• The prepatent period (time from infection to egg shedding) ranges from 2-9 weeks for most helminths, meaning stool testing may be negative despite active infection 1, 3

Most Likely Parasites from Dogs

The worm vomited by the dog is most likely:

• Toxocara canis (dog roundworm) - causes visceral larva migrans in humans 1
• Ancylostoma caninum (dog hookworm) - causes cutaneous larva migrans or intestinal infection in humans 1, 3
• Ascaris-like roundworms that can cause human infection 1, 2

Recommended Treatment Protocol

For Adults and Children Over 2 Years

• Albendazole 400 mg as a single oral dose 1, 2, 4
• Take with food to enhance absorption 4
• Consider repeating the dose in 2 weeks if exposure was significant or symptoms develop 3, 5

For Children Under 2 Years

• Consult with pediatric infectious disease specialist before treatment 3
• If treatment deemed necessary, same 400 mg dose applies regardless of age for single-dose helminth treatment 5

For Pregnant Women

• Pregnancy testing is mandatory before albendazole administration in women of reproductive potential 4
• Albendazole is contraindicated in pregnancy due to embryo-fetal toxicity 4
• If treatment is essential, pyrantel pamoate is the preferred alternative during pregnancy 6

Alternative Treatment Considerations

If Broader Coverage Needed

• For patients with eosinophilia or suspected but undetected parasitic infection, combination therapy with ivermectin 200 μg/kg plus albendazole 400 mg provides broader coverage 3
• This combination is particularly useful if Strongyloides exposure is possible, as albendazole alone has poor efficacy against this parasite 7

Coverage Spectrum of Albendazole

Albendazole 400 mg single dose effectively treats:

• Ascaris lumbricoides (roundworm) 1, 2
• Hookworms (Ancylostoma duodenale, Necator americanus) 1, 3
• Pinworms (Enterobius vermicularis) 5, 6
• Toxocara species (though primarily causes visceral larva migrans requiring symptomatic management) 1

Important Clinical Caveats

What Albendazole Does NOT Cover Well

• Strongyloides stercoralis requires ivermectin, not albendazole 1, 7
• Tapeworms (Taenia species) require different dosing: albendazole 400 mg daily for 3 days or praziquantel 1
• Toxocara visceral larva migrans may require symptomatic treatment with corticosteroids rather than anthelmintics 1

Safety Monitoring

• No routine laboratory monitoring needed for single-dose therapy 4
• Monitor for hepatotoxicity and bone marrow suppression only if treatment extends beyond 14 days 5, 4
• Discontinue if clinically significant blood count changes or liver enzyme elevations occur 4

Contraindications

• Known hypersensitivity to benzimidazole compounds 4
• Pregnancy (obtain pregnancy test first in women of reproductive potential) 4

Household Contact Management

Treating Family Members

• Treat all household members simultaneously if treating for pinworms, as reinfection rates are high 5, 6
• For other helminths, treat household contacts only if they had similar exposure to the infected dog 1
• Consider treating the dog concurrently with veterinary anthelmintics to prevent reinfection 6

Prevention Counseling

Reducing Future Exposure Risk

• Regular deworming of household pets (veterinary consultation) 6
• Hand hygiene after contact with pets and before meals 5, 6
• Proper disposal of pet feces 1
• Wearing shoes outdoors to prevent hookworm larval penetration 3
• Avoiding areas contaminated with animal feces 1

When to Seek Further Evaluation

Red Flags Requiring Specialist Referral

• Development of eosinophilia (suggests active helminth infection) 1
• Persistent gastrointestinal symptoms after treatment 1, 2
• Respiratory symptoms (cough, wheezing) suggesting Loeffler's syndrome from larval migration 1, 2
• Neurologic symptoms (could indicate neurocysticercosis if Taenia solium exposure) 4
• Visual changes (retinal involvement with certain parasites) 1