Ascaridosis is a disease caused by parasitization in the human body by roundworms-ascarids (Ascaris lumbricoides, string).

Infection occurs by ingesting food or soil particles (fecal-oral transmission mechanism) contaminated with feces containing ascarid eggs. After passing the stomach, the eggs become "stuck" in the villi of the upper small intestine. Larvae emerge from the eggs, which immediately penetrate through the intestinal wall into the blood vessels. Through the bloodstream, the larva enters the system of the inferior genital vein, then through the blood sequentially into the following organs: the liver, the heart, and the lungs. From the lungs, the larva ascends along the epithelium of the respiratory tract into the larynx, into the pharynx, and then is swallowed again with saliva into the stomach and intestines.

After 2.5 months, adults develop from larvae in the small intestine, which become capable of reproduction – they begin to actively lay eggs. Each female can lay about 200 thousand eggs (!) per day, the eggs come out with feces. The life span of an ascarid is one to two years: after death, the parasite is eliminated from the body. Consequently, the detection of ascariasis in a patient for several years indicates re-infection, which most often happens when the patient does not observe the rules of personal hygiene. Clinical manifestations depend on the number of ascariids: from an asymptomatic course to a life–threatening condition.

There are two stages of the disease: early (migratory) and late (intestinal).

• In the early larval stage, when the parasite passes practically through the whole body, internal organs such as liver, spleen, lungs, heart, pancreas... therefore, the disease will manifest itself as inflammation of these organs (inflammation of the lungs, pancreatitis, hepatitis, myocarditis, cholecystitis...).
• In the late stage of the disease, the patient may have a prolonged increase in body temperature up to 37.5 C, general weakness and malaise, headaches, the appearance of allergic reactions, skin rashes, nausea, abdominal discomfort, sleep disturbance. Laboratory tests show a sharp increase in the number of eosinophils.

A formidable complication of ascaridosis is often acute intestinal obstruction, when the worms are tangled in the form of a ball, stuck in the intestinal lumen and do not give fecal matter to go. Subsequently, the blood supply to the intestine is disrupted, which necrotizes ("dies off"). Ascaridosis can be diagnosed only when their eggs are detected in the feces or adults during surgery. The second option tends to be accidental. The disadvantage of the first method is that the test is performed using a microscope, which does not exclude false negatives due to human error.

Detection of immunoglobulins G to ascarids is a specific blood test based on the detection of the body's reaction to the presence of the pathogen Ascaris lumbricoides in it. There are several classes of immunoglobulins: A, M, G, E, D. G – means prolonged contact of the immune system with the parasite, that is, the chronic course of the disease. The positive side of the method is the exclusion of errors as a result due to the human factor, the possibility of detecting a helminth in the preclinical stage of the disease.