Toxocariasis, also known as roundworm infection, is a zoonotic disease that can spread from animals to people. The only hosts for the roundworm species that frequently infect humans are dogs and cats.
Ascarid nematodes, such as roundworms, reproduce in their host’s gastrointestinal tract. Toxocara canis and Toxocara cati are parasites that live on dogs and cats, respectively. Due to the widespread presence of dogs and cats worldwide, those species can be found everywhere. Compared to Toxocara cati, Toxocara canis causes human infections more frequently.
The roundworm’s life cycle starts when eggs are passed along with feces and dumped in the ground. The eggs must be infectious for two to four weeks. A new host is infected by ingesting the eggs. When the eggs hatch, larvae are released that breach the small intestine’s walls and enter the bloodstream. The larvae can move from the blood to various body organs.
The roundworm matures into an adult worm in its natural host after returning to the small intestine to complete its life cycle. The process takes about 60 to 90 days after hatching. The cycle is then restarted when the worms mate and lay eggs, which are then excreted in the feces. Lower temperatures can cause the incubation period to be extended, and in northern climates, the eggs may remain dormant all winter.
The natural hosts of Toxocara canis and Toxocara cati are not humans. There is a roundworm that affects humans called Ascaris lumbricoides, but it is less common than the roundworms that affect cats and dogs because it primarily affects areas with poor sanitation.
Humans who consume the roundworm larvae from cats or dogs risk infection and illness as the larvae move through organs and tissues. When a larva enters the eye, it can cause the illness ocular larva migrans (OLM). OLM can lead to blindness. The condition known as visceral larva migrans (VLM), which affects the organs or central nervous system, is caused by roundworm larva.
Humans cannot contract the infection from one another because the larvae do not develop into adult worms and reproduce on them.
Paratenic hosts, which are different animals, can also transmit toxocara. When a cat or dog—the primary host—eats eggs consumed by another animal, such as a rodent, the eggs may hatch and produce larvae that continue to develop into adult worms.
In puppies, the T. A canis’s life cycle is completed when adult worms lay new eggs. However, the process stops in older dogs at the second of the four larval stages, and the larvae remain in the host for a very long time. Dogs quickly contract toxocara again if not kept in a toxocara-free environment.
Larvae reactivate during pregnancy and move through the placenta to infect the fetus. Puppies are at a high risk of spreading toxocara to humans if they are not treated because they typically have the infection at birth.
Additionally, puppies or kittens can contract toxocara from their mother’s milk. Soil contaminated with toxocara eggs is a more frequent source of infection for people, usually children.
Important measures to prevent the transmission of toxocara roundworms to humans include maintaining good hygiene, routine deworming of pet dogs and cats, and preventing dogs and cats from playing in areas where children are present.
How do I prevent my dog from getting roundworms?
Because roundworms can enter your dogs body in many different ways, it is essential to keep your dogs living area clean, remove feces 
regularly, and, if possible, prevent your dog from eating wild animals that may carry roundworms.
Puppies should be treated for roundworms at 2, 4, 6, and 8 weeks old, followed by a monthly preventive treatment, to get rid of the parasites that are passed from the mother dog. Examinations of the feces (stool) should be done two to four times during the first year of life and once or twice a year in adults. To reduce the risk of transmission, nursing mothers should continue receiving monthly preventive care and treatment alongside their puppies.
Many heartworm preventives also control roundworms. Consult your dog’s veterinarian for the best prevention and treatment options.
How will roundworms affect my dog?
Adult roundworms live in the affected dogs intestines. However, dogs with severe roundworm infections, especially puppies, exhibit diarrhea, vomiting, weight loss, dull hair, and a potbellied appearance. Many dogs do not exhibit symptoms of infection. If the roundworms enter the lungs, the dog may cough.
The adult roundworms may be visible in your dog’s feces or vomit. They may be several inches long and appear white or light brown.
Is it true that children can get roundworm infections?
The larvae of Toxocara canis can invade the tissues and encyst in various organs if the infectious eggs are ingested by people. Humans act like any other paratenic or accidental host. A young child may develop clinical disease if they consume a lot of infected eggs.
Very rarely, visceral larval migrans (roundworm larval migration) may cause liver issues. The larvae can occasionally (ocular larval migrans) migrate into the eye and result in blindness. The Centers for Disease Control (CDC) advises that all dogs undergo monthly deworming due to the possibility of roundworm infection in humans.
Treatment is simple and effective. To eliminate adult roundworms in the intestine, there are numerous medications that are both secure and efficient. Numerous monthly heartworm preventives include drugs that work well against intestinal roundworms and help ward off subsequent infections. Some of these treatments only kill adult worms, leaving larvae that are migrating or encysting unaffected. Recently created items will also have an impact on the larval stages. Your vet will give you advice on the ideal course of action for your pet’s treatment and prevention.
FAQ
How easy is it for humans to get worms from dogs?
The parasite cannot be transferred directly from dogs to people.
How easy is it for humans to get roundworms?
Infections with roundworms typically occur when people unintentionally ingest soil, sand, or plants that have been contaminated with infected animal feces. Hookworm infections happen when larvae penetrate the skin. This typically occurs when people sit or walk barefoot on contaminated sand or soil.
Can you get roundworms from your dog licking you?
Dogs can lick humans and transmit parasites like giardia, hookworm, and roundworm. Salmonella can also be passed from your dog to you or the other way around.
Are roundworms easily spread?
By sharing towels, hats, combs, and other personal items with others, you can spread ringworm quite easily. The fungi can survive on objects for a long time. In the pool area, public showers, and locker rooms, wear shower thongs or water-resistant shoes. This helps stop you from spreading athlete’s foot to other people if you have it.