Ascariasis is a helminthic disease, the etiological agents of which are roundworms – ascariids that parasitize in the human small intestine. The early phase of ascariasis occurs with the phenomena of general malaise, fever, skin rash, hepatosplenomegaly, lymphadenitis, dry cough. In the chronic phase, the symptoms of gastrointestinal tract damage come to the fore: decreased appetite, nausea, diarrhea, abdominal pain. In order to detect ascariasis, serological reactions are carried out, feces are examined for helminth eggs. Ascariasis therapy is carried out with anthelmintic drugs (vermox, decaris, pyrantel); additionally, antihistamines, enzyme preparations, probiotics are prescribed.
Ascariasis is an intestinal nematode caused by human ascaris (Ascaris lumbricoides). Ascariasis is a widespread anthroponotic helminthiasis, second in frequency only to enterobiosis. The disease occurs everywhere, in various climatic latitudes (with the exception of permafrost zones and dry deserts); more often affects children (65%). According to WHO, about 1 billion people are infected with ascariasis. people on the planet; among the population of regions with warm and humid climates, ascariasis is detected in 30-90% of cases. Due to the high susceptibility of the population and the possible risk of severe, including apart from surgical complications, ascariasis is the subject of increased attention in infectious diseases, parasitology, pediatrics.
The causative agent of ascariasis – Ascaris lumbricoides (ascaris) belongs to the class of roundworms. Ascarids have an elongated fusiform shape, yellowish-pink color. Helminths are bisexual: the length of the female ascaris is 20-40 cm, the male is 15-25 cm, the width is 4-6 mm. Every day, a sexually mature individual of the ascaris is able to lay more than 200 thousand non-invasive eggs, which are excreted with feces into the external environment. In the soil, under favorable temperature and humidity conditions, eggs mature to the invasive stage within 12-14 days, i.e. to a condition capable of causing disease.
A potential source of the spread of ascariasis is a person infected with helminths. Invasion is realized by means of a fecal-oral mechanism, in an alimentary way. This means that eggs released into the external environment and ripened in the soil before the invasive stage enter the body of the new host through the mouth from unwashed hands, household items, as well as when eating contaminated vegetables, berries, fruits, etc. if hygiene measures are not observed. The incidence of ascariasis is more susceptible to children, workers of sewage treatment plants, agricultural workers, gardeners, etc. The season of increased risk of infection lasts from spring to autumn.
Further development of ascariids occurs in the host body, where the early (migration) and late (intestinal) phases of ascariasis take place. In the human gastrointestinal tract, namely in the small intestine, ascarid larvae come out of eggs, which penetrate into venous vessels, enter the portal vein with blood flow and then through the blood vessels – into the capillary network of the lungs. There the larvae penetrate into the alveoli, rise into the lumen of the bronchi, trachea and pharynx. Together with bronchial secretions and saliva, they are swallowed and returned to the small intestine, where mature individuals develop from them. The full cycle of transformation of an invasive egg into a sexually mature ascaris is about 2.5-3 months.
In the early phase of ascariasis, the body is sensitized by the products of larval metabolism, as well as mechanical traumatization of intestinal tissues, liver, blood vessels, and bronchopulmonary system. In the late phase of ascariasis, the toxic effect on the body of the waste products and decay of adult ascariids, injuries of the small intestine, impaired absorption of nutrients, suppression of immunity is more pronounced.
The clinical symptoms of ascariasis are diverse and depend on the massiveness of the invasion, the age of the patients, and the phase of the disease. Allergic, infectious-toxic, hepatic and pulmonary syndrome may develop during the migration phase of larvae. This stage of ascariasis in children is often asymptomatic.
Allergic manifestations are characterized by vesicular or urticular rashes on the trunk, hands or feet, severe itching. Infectious-toxic syndrome in ascariasis is accompanied by febrile fever, weakness, malaise, sweating, lymphadenopathy. Signs of hepatic syndrome may include enlargement of the liver and spleen, moderate soreness in the right hypochondrium, increased activity of liver enzymes, etc. In almost all cases, bronchopulmonary syndrome (eosinophilic pneumonia, Leffler syndrome) develops during the migration phase of ascariasis. It occurs with a dry or wet cough, shortness of breath, chest pain, wheezing in the lungs. Often, exudative pleurisy develops against this background. When examining pleural effusion obtained as a result of thoracocentesis, eosinophils are found in large numbers, rarely ascarid larvae.
The late (intestinal) phase of ascariasis is characterized by the development of 2 clinical syndromes – gastrointestinal and asthenovegetative. From the gastrointestinal tract during this period, there is a decrease in appetite, nausea in the morning, vomiting, abdominal pain, diarrhea, constipation, bloating, weight loss. Toxic effects on the nervous system can be manifested by weakness, sleep disorders, memory loss (in children – delayed psychomotor development), meningism phenomena, epileptiform seizures.
Massive helminthic invasion can cause complications: for example, during the migration of ascariids into the bile and pancreatic ducts, mechanical jaundice, purulent cholangitis, multiple liver abscesses, acute pancreatitis, appendicitis, peritonitis can develop. It is possible to develop mechanical obstruction of the respiratory tract by helminths, leading to acute ascariasis asphyxia. In children, ascariasis is most often burdened by intestinal obstruction. Ascariasis in pregnant women contributes to severe toxicosis, delayed fetal development, complicated course of labor and the postpartum period.
To suspect the presence of ascariasis in a child or an adult, complaints of unexplained and persistent fever, cough, skin rashes, digestive disorders, weight loss, nervousness allow. Detection of antibodies in the blood serum with the help of immuno-enzyme analysis and latex agglutination reaction helps to recognize helminthic invasion in the early phase. Changes in the general blood test are characterized by eosinophilia, increased ESR, small leukocytosis, anemia. During lung radiography in patients with bronchopulmonary syndrome, so-called “Leffler’s volatile infiltrates” are detected – foci of infiltration that change their position along with the migrating larva. Microscopic examination of sputum may reveal ascarid larvae.
In the chronic phase, the main method of diagnosing ascariasis is the examination of feces for helminth eggs. However, in this way, it is possible to detect an invasion only 3 months after infection. Taking into account the probability of parasitizing only males, as well as immature females or old individuals, helminth eggs may be absent in the feces: in this case, diagnostic deworming is carried out. During radiography of the small intestine, against the background of a contrasting mass, you can see ascaris in the form of light ribbons or tangles located in the lumen of the intestine.
In the early phase, ascariasis must be distinguished from pneumonia, tuberculosis, lung cancer. In the chronic phase, differential diagnosis is primarily required with duodenitis, enteritis, cholecystitis and other diseases of the digestive system.
The treatment of ascariasis is carried out under the supervision of an infectious disease specialist (a pediatric infectious disease specialist or pediatrician) and consists of organizational and routine measures, deworming, dispensary observation and prevention of re-infection. General recommendations relate mainly to the observance of a diet with a high content of vitamins, animal proteins and limited carbohydrates.
Drug therapy is carried out with anthelmintic drugs, of which tiabendzole or mebendazole are prescribed in the early phase of ascariasis, and levomizole, pyrantel, etc. are prescribed in the intestinal phase. To reduce allergization simultaneously with anthelmintic drugs, a short course of antihistamines is recommended. Enzymes (pancreatin) are used to normalize digestive function. Correction of intestinal microflora is carried out with the help of probiotic drugs. Control of the effectiveness of anthelmintic therapy is carried out 2 weeks and 1 month after the course of treatment three times. A patient who has had ascariasis is monitored for a period of 3 years with an annual coproovoscopy.
Prognosis and prevention
Prevention of ascariasis should be aimed at timely detection and deworming of patients, hygienic education of children, increasing the level of sanitary culture among adults. Compliance with basic hygiene standards will help to avoid infection with ascariasis: washing hands before eating, after going outside, going to the toilet; thorough washing of berries, fruits, vegetables under running water before serving. With an uncomplicated course of ascariasis, the prognosis is favorable. In the absence of repeated invasion, self-healing occurs after about a year due to the natural death of ascaris. Complications develop relatively rarely, mainly in children and in weakened patients.