Roundworms are actual worms of many different types. In discussing human health, the most important types to consider are Ascaris lumbricoides, which may be called the “human” roundworm. Other important kinds are Toxocara canis and Toxocara cati. All of these worms may live as parasites in the human body and cause severe or chronic illness.
All three species of roundworms live in the gut, and are excreted through feces. They may have a “spaghetti-like” appearance, but people don’t tend to eat whole worms. Instead they get the eggs of the worms into their mouth, usually by touching things like soil where they live, by improper cleaning after toileting, or by eating unwashed or uncooked fruits and vegetables in areas where there is poor sanitation. This is usually what causes ascariasis, or infection with human roundworm. When people get toxocara infection, called toxocariasis, principle cause is exposure to animal feces or improper handwashing after playing with infected pets (often puppies and kittens).
Human roundworms and ascariasis most often occur in developing countries, especially because wastewater may be reused on crops. Some people don’t have many symptoms when they get this infection, but other people might develop fever, stomach upset, fatigue, and stomach pain. Greatest danger of this form of infection is that the roundworms will migrate out of the stomach into other areas of the body, where they can affect the lungs or other organs. Though this doesn’t always occur, and some people in developing countries have chronic ascariasis, treatment is very important to eliminate the worms.
The same holds true for people with toxocariasis infections. Worms don’t necessarily remain in the gut and need to be eliminated so that spread doesn’t begin to occur in other organs. Similar symptoms can be present for toxocariasis and ascariasis. They should indicate a trip to the doctor to get diagnosis.
Usually, analyzing stool samples for presence of worms or eggs diagnoses infection with roundworms. Sometimes people will notice excretion of worms in their own stool, since the worm can be fairly large. Typical treatment involves using antiparisitic medications like mebendazole and piperazine, and then retesting at a future point to be certain infection is cleared.
In developing countries it is much harder to prevent infection with human roundworms because of their prevalence, though some people take a once monthly dose of anti-parasitic medicine. In developed countries prevention may be easier because of stricter standards in food production and growth. Animal lovers must still be careful about toxocariasis, and best bets for prevention included deworming animals frequently, using safe measures when cleaning up feces (which should be cleaned up regularly), and making sure to thoroughly wash hands after animal handling.