Roundworms are a type of parasitic worm that can infect humans and animals. They have a long, round body and can range in size from a few millimetres to several metres. Roundworms can cause various diseases and symptoms, depending on the species and the part of the body they affect.

Some of the most common roundworm infections in humans are:

• Ascaris lumbricoides: This is the most widespread roundworm infection, affecting about one billion people worldwide. It can cause abdominal pain, diarrhoea, malnutrition and intestinal obstruction. The worms can also migrate to other organs, such as the lungs, liver and brain, causing complications.
• Hookworms: These are small worms that attach to the lining of the small intestine and feed on blood. They can cause anaemia, weakness, weight loss and skin infections. Hookworms can enter the body through the skin, usually by walking barefoot on contaminated soil.
• Pinworms: These are tiny worms that live in the large intestine and anus. They can cause itching around the anus, especially at night, and sometimes vaginal irritation. Pinworms are spread by ingesting their eggs, which can be found on bedding, clothing, toys and other objects.
• Whipworms: These are thin worms that live in the large intestine. They can cause diarrhoea, abdominal pain, rectal prolapse and growth retardation in children. Whipworms are transmitted by ingesting their eggs from contaminated soil or food.
• Filariasis: This is a group of diseases caused by thread-like worms that live in the lymphatic system or under the skin. They can cause swelling of the limbs (elephantiasis), skin lesions, eye infections and fever. Filariasis is spread by mosquitoes or flies that carry the worms.

Roundworm infections are more common in warm tropical and subtropical countries, where sanitation and hygiene are poor. Children are more often affected than adults. Roundworm infections can be diagnosed by examining stool samples or blood tests. Treatment is usually very effective with anti-parasitic drugs. Prevention involves improving sanitation, wearing shoes, washing hands and avoiding raw or undercooked food.

Here are some more details about roundworm infections:

Ascaris lumbricoides is the largest and most common roundworm that infects humans. It can grow up to 40 cm long and live for up to two years in the intestine. The female worm can produce up to 200,000 eggs per day, which are passed out in the stool and can survive in the soil for years.

The infection cycle begins when a person ingests the eggs from contaminated food, water or soil. The eggs hatch in the small intestine and release larvae, which penetrate the intestinal wall and enter the bloodstream. The larvae travel to the lungs, where they cause coughing and wheezing. They then migrate up the airways and are swallowed back into the intestine, where they mature into adult worms.

The symptoms of ascaris infection depend on the number and location of the worms. Some people may have no symptoms or only mild ones, such as abdominal discomfort, nausea, loss of appetite and weight loss. Others may have more severe symptoms, such as intestinal obstruction, vomiting, fever, blood in the stool and malnutrition. The worms can also cause complications by migrating to other organs, such as the liver, pancreas, gallbladder, appendix and brain. These can result in jaundice, inflammation, abscesses, seizures and coma.

The diagnosis of ascaris infection is usually made by finding eggs or worms in the stool sample. Sometimes, worms may be seen in vomit or sputum. Blood tests may show eosinophilia (high levels of a type of white blood cell) and anaemia (low levels of red blood cells). Chest X-rays may show signs of lung inflammation or damage.

The treatment of ascaris infection is usually simple and effective with anti-parasitic drugs, such as albendazole or mebendazole. These drugs kill the adult worms and prevent them from producing eggs. The dead worms are then expelled in the stool. Sometimes, surgery may be needed to remove worms that cause obstruction or complications in other organs.

The prevention of ascaris infection involves improving sanitation and hygiene practices, such as using latrines or toilets, washing hands with soap and water before eating and after defecating, boiling or filtering drinking water and cooking food thoroughly. It also involves deworming programs that provide regular anti-parasitic drugs to children and high-risk groups.