Ascaris lumbricoides, IgG antibodies
Why this test?
The human immune system reacts to ascaris by producing specific antibodies. First, IgM are produced, which can be detected only within 1-2 weeks after infection, then their level drops below the determined values. After IgM, the production of IgG begins, providing immunity to reinvasion.
However, this immunity is unstable, and in the case of treatment of a person from ascariasis after 3 months, IgG is usually not detected. Thus, although the diagnosis cannot be made only on the basis of determining the titer of Ascaris lumbricoides, IgG (the results must be considered together with the history and clinical symptoms), early diagnosis allows to start therapy before complications of ascariasis appear.
In addition, this analysis helps to evaluate the effectiveness of the treatment of ascariasis.
In what cases is it prescribed?
With complaints that suggest ascariasis.
In case of ascariasis, two phases are distinguished - early (migratory) and late (intestinal). The early phase can be evidenced by weakness, malaise, headache, sometimes fever up to 38 ° C, enlargement of the liver, spleen, lymph nodes, skin rash, local or systemic itching of the skin, signs of lung damage (dry cough, shortness of breath, chest pain). . In the late phase, symptoms of damage to the gastrointestinal tract are added to them: appetite disorders, nausea, loose stools or, on the contrary, constipation, abdominal pain. Many patients note allergies that are difficult to treat, and persistent (long-term, resistant to therapy) iron deficiency anemia.
According to various data, about 1.27 billion people, or approximately 1⁄4 of the population, are infected with ascariasis worldwide. The causative agent of the disease is the human roundworm (Ascaris lumbricoides), which belongs to the class of roundworms. Infection occurs when eating food (poorly washed vegetables, more often root crops) infected with roundworm eggs, as well as through dirty hands. Ascaris eggs enter the small intestine, where they hatch into larvae. Those, in turn, penetrate through the wall of the intestine into the bloodstream and spread throughout the body, reaching the liver, heart and lungs, where they penetrate into the alveoli through the walls of the pulmonary capillaries. Larvae migrate from the respiratory tract into the oral cavity and are swallowed again. The larva got into the intestines again after 2.5-3 months. develops into an adult.
Adult roundworms live in the small intestine, where females lay about 200,000 eggs per day after fertilization. Immature helminth eggs are released into the environment, and ripening occurs only at a temperature and humidity favorable for their development. The total lifespan of roundworms is from 6 to 16 months, so the presence of roundworms in one person for several years can only be explained by repeated infection.
The larvae, being in the internal organs, feed on blood serum and erythrocytes. Complications of ascariasis: intestinal obstruction, pancreatitis, appendicitis, cholangitis, caused by migration of ascaris to other organs (pancreas, gall bladder, large intestine), where conditions are created for bacterial infection to join.
An important role in the detection of ascariasis is played by laboratory diagnostics, and in particular the immunological method - the determination of specific antibodies to ascaris. It can be used both in the migratory and in the intestinal stage of the disease.
In addition, the intestinal stage of Ascaris lumbricoides, IgG, can be diagnosed by stool analysis for ascaris eggs. However, in some cases, it is necessary to carry out this study repeatedly, since ascaris eggs are not released constantly. Peripheral blood eosinophilia is characteristic for various stages of the disease, and ESR is usually elevated as well. The number of leukocytes, as a rule, is normal. Only in the case of joining a bacterial infection, leukocytosis is observed.