Ascariasis – intestinal nematodes caused by human Ascaris (Ascaris lumbricoides). Ascariasis is a common anthroponosis helminthiasis, second in frequency only to the enterobiasis. The disease is found everywhere, in different climatic latitudes (except in areas of permafrost and dry deserts); most commonly affects children (65%). According to the who, ascariasis infected about 1 billion people on the planet; among the population of regions with warm and humid climate ascariasis are detected in 30-90% of cases. Due to the high susceptibility of the population and possible risk of developing severe, including surgical complications ascariasis is the focus of attention of infectiology, Parasitology, Pediatrics.
Causes of ascariasis
The causative agent of ascariasis is Ascaris lumbricoides (Ascaris) belongs to the class of roundworms. Ascarids have an elongated spindle shape, yellowish-pink color. The worms are dioecious: the length of the female roundworm is 20-40 cm, the male — 15-25 cm, width of 4-6 mm. Daily to sexually Mature adult roundworm can lay more than 200 thousand non-invasive sub eggs, which are excreted in faeces into the external environment. In the soil, under favorable temperature and humidity conditions for 12-14 days there is the maturation of eggs to the infective stage, i.e. to a condition able to cause disease.
A potential source of the spread of ascariasis stands infected with helminths. Infestation is achieved by a fecal-oral mechanism through the alimentary. This means that dedicated to the environment and ripened in soil to the infective stage, the eggs enter the body of a new host through the mouth with unwashed hands, utensils, as well as by eating contaminated vegetables, berries, fruits, etc. at non-observance of hygienic practices. The incidence of ascariasis in the more vulnerable the children, the workers of sewage treatment plants, agricultural workers, gardeners etc. the Season of increased risk of infection lasts from spring to autumn.
Further development of Ascaris occurs in the host organism, where the early (migration) and late (intestinal) phase of ascariasis. In the digestive tract of human beings, namely in the small intestine, the eggs are larvae of the roundworm, which penetrate into the veins, with blood flow get into the portal vein and then the blood vessels in the capillary network of the lungs. There, the larvae penetrate the alveoli, ascend into the lumen of the bronchi, trachea and throat. Along with bronchial secretions and saliva, they are swallowed and return to small intestine, where they develop Mature individuals. A complete cycle of transformation of infective eggs in the sexually Mature Ascaris is about 2.5-3 months.
In the early phase of ascariasis occurs sensitization of the organism metabolic products of larvae, as well as mechanical trauma to the tissues of the intestine, liver, blood vessels, and respiratory system. In the late phase of ascariasis is more pronounced toxic effect on the organism of waste products and decay of Ascaris adults, injuries to the small intestine, malabsorption of nutrients, suppression of the immune system.
Symptoms of ascariasis
Clinical symptoms of ascariasis is diverse and depends on the massiveness of invasion, age of patients, phase of the disease. In the phase of migration of larvae may develop an allergic, toxic, hepatic and pulmonary syndrome. This phase of ascariasis in children are often asymptomatic.
Allergic reactions are characterized by vesicular or urticarial rash on the trunk, hands or feet, severe itching. Infectious-toxic syndrome in ascariasis accompanied by febrile fever, weakness, malaise, sweating, lymphadenopathy. Signs of liver syndrome may be an increase in liver and spleen, moderate pain in the right hypochondrium, increased activity of liver enzymes, etc. in Almost all cases in the migration phase of ascariasis develops respiratory syndrome (eosinophilic pneumonia, syndrome Leffler). It flows with wet or dry cough, shortness of breath, chest pains, wheezing in the lungs. Often this background develops pleural effusion. In the study of pleural effusion, the resulting thoracocentesis in a large number of eosinophils are found, rarely larvae of Ascaris.
The late (intestinal) phase of ascariasis is characterized by the development of 2 clinical syndromes — gastrointestinal and asthenovegetative. From the blood during this period there is a decrease in appetite, nausea in the mornings, vomiting, abdominal pain, diarrhea, constipation, bloating, weight loss. Toxic effects on the nervous system may be manifested by weakness, sleep disturbance, memory loss (in children with psychomotor retardation), meningism phenomena, epileptiform convulsions.
A massive worm infestation can cause complications, so during the migration of Ascaris in the bile and pancreatic ducts can develop obstructive jaundice, suppurative cholangitis, multiple liver abscesses, acute pancreatitis, appendicitis, peritonitis. Perhaps the development of mechanical obstruction of the respiratory tract helminths, which leads to acute askaridoze asphyxia. In children, ascariasis is most often intestinal obstruction. Ascariasis in pregnant women contributes to severe toxemia, fetal growth retardation, complications during labor and the postpartum period.
Diagnosis of ascariasis
To suspect the presence of ascariasis in a child or adult allow complaints of unexplained and persistent fever, cough, skin rashes, digestive disorders, weight loss, nervousness. To recognise worm infestation in the early phase helps identify antibodies in the serum using enzyme immunoassay and the reaction latex-agglutination. Changes in General blood analysis are characterized by eosinophilia, elevated ESR, small leukocytosis, anemia. If radiography of the lungs in patients with bronchopulmonary syndrome are found the so-called “volatile infiltrates Leffler” — foci of infiltration, which changes its position along with the migrating larva. Microscopic examination of sputum may reveal larvae of the Ascaris.
In the chronic phase the primary method for diagnosing ascariasis is the research of a feces on eggs of helminths. However, the way to identify the infestation only after 3 months after infection. Given the likelihood of parasitism only males and immature females or older animals, helminth eggs in feces may be absent: in this case, is the diagnostic deworming. When radiography of the small intestine in contrast you can see masses of ascarids in the form of light strips or coils, disposed in the lumen of the gut.
In the early phase of ascariasis to be distinguished from pneumonia, tuberculosis, lung cancer. In the chronic phase the differential diagnosis, primarily required with duodenitis, enteritis, cholecystitis and other diseases of the digestive system.
Treatment and prevention of ascariasis
Treatment of ascariasis is performed under the control of infectious diseases (children’s infectious diseases specialist or paediatrician) and consists of the organizational security measures, deworming, clinical supervision and prevention of re-infection. General recommendations relate mainly to diet with a high content of vitamins, animal protein and limiting carbohydrates.
Drug therapy is carried out de-worming drugs, of which the early phase of ascariasis is assigned thiabendazole or mebendazole and intestinal – levamisole, Pyrantel, etc., For reduction sensitization simultaneously with the de-worming drugs recommended a short course of antihistamines. Normalization functions are used digestive enzymes (Pancreatin). Correction of the intestinal microflora is performed using probiotic preparations.
Monitoring the effectiveness of antihelminthic therapy is 2 weeks and 1 month after treatment three times. For ill with ascariasis a patient set follow-up period of 3 years, with annual moprovskaja. Prevention of ascariasis should be aimed at timely detection of sick and deworming, health education, increasing of level of sanitary culture among adults. To avoid infection of ascariasis will help the observance of the elementary rules of hygiene: washing hands before eating, after the streets, visiting the toilet; thorough rinsing under running water berries, fruits, vegetables before serving. In uncomplicated ascariasis the prognosis is favorable. In the absence of re-infestation after about a year on their own due to natural mortality of Ascaris. Complications are relatively rare, mainly in children and in debilitated patients.