No. A dog cannot pass heartworms to a human. Heartworms (Dirofilaria immitis) are parasitic worms that generally affect dogs and cats. They are transmitted through mosquito bites only, and it’s very rare for a human to get sick from them.
Dirofilaria immitis is a species of parasitic worm better known by pet owners as heartworms.
Heartworm larvae can grow into adult worms in your dog’s blood and block major blood vessels. If untreated, a dog
Very few cases of heartworms in humans have been reported, and those are not animal-to-human cases.
Both dogs and humans can get heartworm infections through mosquito bites only. Your dog can’t give it to you.
When a mosquito bites an infected animal, it takes in undeveloped heartworms known as microfilariae. Inside the mosquito, these develop into larvae. The next time the mosquito bites another animal, it passes the larvae into the new host’s bloodstream.
What happens next varies by species.
- In animals, the larvae eventually mature into adult heartworms. They can then cause dirofilariasis, a full-blown infection that can block major arteries or cause organ infections.
- In humans, heartworm larvae never fully mature. As young heartworms die, the body (most commonly your lungs) reacts to their tissue with inflammation as it tries to destroy them. Human
pulmonary dirofilariasis often doesn’t manifest with evident symptoms.
The symptoms of heartworm infections in animals and humans differ because of how they develop in the bloodstream. You may not always experience any symptoms because the heartworms will die before maturity in a human host.
Symptoms and signs of human pulmonary dirofilariasis may include:
- a small round lesion (“coin” lesions) in the lung tissue that
could mimic a cancerous growth - abnormal cough
- hemoptysis (coughing up blood)
- pain in the chest
- wheezing
- chills
- fever
- buildup of fluid around the lungs (pleural effusion)
Seek immediate medical attention if you experience these symptoms, whether you’ve been bitten by a mosquito or not.
Mosquito bites may appear as red, itchy bumps with dots in the middle.
These symptoms can also indicate other, more serious conditions.
You may not realize you’ve had a Dirofilariasis infection until a doctor sees a coin lesion on a chest X-ray.
These lesions appear as darkened spots on X-rays or computed tomography (CT) imaging tests. They mostly develop near the edge of the lungs.
A lesion may also be called a granuloma. These result from inflammation and buildups of immune cells known as histiocytes that fight the heartworm infection.
A doctor may also want to take a tissue sample (biopsy) from the lung to test for heartworm infection if they spot one of these lesions on an X-ray. They may also test lung tissue to rule out other possible causes of your symptoms. In rare cases, a coin lesion can indicate a bacterial infection, tuberculosis, or lung cancer.
Heartworms don’t live long in human blood, so you won’t need to have heartworms removed through either medication or surgery. Treatment for heartworms in humans focuses on treating any granulomas or lesions that appear on an imaging test.
If a granuloma isn’t causing any symptoms or blockage in your arteries, you probably won’t need any treatment.
If a doctor suspects that a granuloma may be cancerous or the result of another, more serious condition, they’ll likely take a tissue sample (biopsy).
To take a tissue sample, a doctor may use one of these methods:
If the doctor finds that a granuloma isn’t cancerous or a result of another condition, you may not need any treatment.
If they believe that granulomas need to be removed, you may need surgery. This will prevent any further symptoms or complications.
If the granuloma is cancerous tissue, the doctor may likely refer you to an oncologist to further examine your bodily tissues for the presence of cancer.
You can’t get heartworms from your dogs, cats, or other pets — only from mosquitoes that carry the infection.
Most heartworm microfilariae (tiny heartworms) die on their way through the skin. Even if they do get into your blood somehow, heartworms can’t mature and will eventually die off.
In most cases, heartworms in humans aren’t a serious problem unless they cause pain, discomfort, and other noticeable symptoms.
Special note for pet owners
Heartworms are serious business for dogs. Without treatment, your dog can experience severe symptoms and even die from an infection.
Ask your veterinarian for heartworm prevention medications for your pet. This is especially important if you live where there are lots of mosquitoes or plan to travel with your pet somewhere with mosquitoes. Think outdoor walks, camping trips, or vacations in humid areas.
If you notice any symptoms of heartworm infection, like cough, fatigue, shortness of breath, or decreased appetite, take your dog to the vet immediately to get tested. If necessary, have it treated for heartworms as soon as possible.