Roundworm disease is caused by infection with parasitic roundworms, which are a type of nematode worm. These worms live inside the intestines or other tissues of humans and animals, and their presence leads to the disease. The most common roundworms that cause disease in humans include *Ascaris lumbricoides*, *Strongyloides stercoralis*, and other ascarids. The root cause of roundworm disease is the ingestion or contact with roundworm eggs or larvae, which then develop into adult worms inside the body.
The life cycle of roundworms typically begins when eggs are passed in the feces of an infected host and contaminate soil, water, or food. People become infected by accidentally ingesting these eggs, often through contaminated hands, food, or water. In some cases, larvae can penetrate the skin, especially when walking barefoot on contaminated soil. Once inside the body, the larvae hatch and migrate through various tissues, including the lungs and intestines, before maturing into adult worms in the small intestine.
For example, *Ascaris lumbricoides* eggs are swallowed, hatch into larvae in the intestines, then migrate through the bloodstream to the lungs. From the lungs, they ascend the airways, are coughed up, swallowed again, and finally settle in the intestines where they grow into adult worms. These adults can be quite large, with females reaching up to 40 cm in length, and they produce millions of eggs daily that are excreted in feces, continuing the cycle.
In animals like cats and dogs, roundworms (ascarids) have a similar life cycle. Puppies and kittens can acquire the infection from their mother before birth or through nursing. The larvae migrate through the animal’s organs and eventually mature in the intestines. Infected animals shed eggs in their feces, contaminating the environment and posing a risk to humans, especially children.
The causes of roundworm disease are closely linked to poor sanitation and hygiene. Contaminated soil, food, or water containing roundworm eggs is the primary source of infection. Lack of proper handwashing, inadequate disposal of human or animal feces, and walking barefoot in contaminated areas increase the risk. In some regions, especially tropical and subtropical areas with warm, moist climates, the eggs survive longer in the environment, making infection more common.
Certain behaviors and conditions also contribute to the spread of roundworm disease. Children playing in dirt or sandboxes contaminated with feces are particularly vulnerable. Eating unwashed vegetables or fruits grown in contaminated soil can also transmit the eggs. In addition, immunocompromised individuals are at higher risk of severe infections, as their bodies cannot effectively control the parasite.
Once inside the body, the presence of roundworms can cause a variety of symptoms depending on the worm burden and the stage of infection. Early larval migration through the lungs can cause coughing, wheezing, and shortness of breath, sometimes accompanied by blood-tinged sputum. This is due to the immune response and tissue damage caused by the larvae moving through lung tissue. Later, adult worms in the intestines can cause abdominal pain, diarrhea, malnutrition, and in severe cases, intestinal obstruction or perforation.
In some infections, the immune system reacts strongly, leading to conditions like Loeffler’s syndrome, characterized by high levels of eosinophils (a type of immune cell) in the lungs, causing inflammation and respiratory symptoms. Heavy infections can be life-threatening, especially in children, due to malnutrition and complications like intestinal blockage.
Preventing roundworm disease involves improving sanitation and hygiene practices. This includes proper disposal of feces, washing hands thoroughly with soap, especially before eating or handling food, and washing fruits and vegetables carefully. Wearing shoes outdoors can prevent skin penetration by larvae. In animals, regular deworming and controlling intermediate hosts like rodents hel
