Hymenolepiasis is a helminthic disease caused by tapeworms (dwarf or rat tapeworm) parasitizing in the small intestine. Often the disease has a subclinical course; the clinic of the manifest form is characterized by pain, dyspeptic, asthenoneurotic and allergic syndromes. The diagnosis is confirmed by the detection of eggs or individuals of helminths in the stool. The drugs of choice for anthelmintic therapy are praziquantel and niclosamide. At the end of the course of treatment, control studies of feces are carried out.
ICD 10
B71.0 Hymenolepiasis
General information
Hymenolepiasis is an intestinal cestodosis that develops when a person is infected with tapeworms of the Hymenolepididae family. Disease occurs almost everywhere, but it is most widespread in Latin America, North Africa, the Middle East, Central Asia, and Transcaucasia – the invasiveness of the population in these regions ranges from 1 to 34%. The main group of cases are children aged 4-14 years: they are infected with hymenolepiasis 3.5 times more often than adults. This is due to insufficiently formed hygienic skills and age-specific immunity of children. The peculiarities of epidemiology and clinical course make the problem of hymenolepiasis relevant not only for infectious diseases, but also for pediatrics and gastroenterology.
Causes
Hymenolepiasis includes helminthiasis caused by tapeworms – dwarf tapeworm (Hymenolepis nana), less often – rat tapeworm (Hymenolepis diminuta), affecting humans and some types of rodents (mice, rats, hamsters). Infection with H. nana has the greatest clinical and epidemiological significance. The dwarf tapeworm is a small cestode 1-5 cm long, 0.5-0.7 mm wide, having a spherical head, neck and ribbon-shaped body. On the head of the helminth there are 4 suckers and a proboscis with a corolla of 25-30 chitinous hooks. The body of the causative agent of hymenolepiasis consists of several hundred segments, part of which, filled with eggs, is separated from the helminth.
The life cycle of the dwarf tapeworm (larval and adult stages) takes place in the human body, which serves as an intermediate and final host of the parasite. The mechanism of transmission of hymenolepiasis is fecal-oral; human infection occurs orally by ingestion of invasive eggs with water, food, unwashed vegetables and fruits, as well as through contaminated hands and household items. In the small intestine, the larva leaves the egg and invades the villi or lymphoid follicles, where the tissue phase of invasion takes place. After 6-8 days, the six-pronged larva (oncosphere) turns into a cysticercoid, which a few days later enters the lumen of the small intestine, where the intestinal phase of helminth development begins. With the help of hooks and suckers, the cysticercoid attaches to the mucous membrane of the small intestine and after 2-2.5 weeks turns into a sexually mature individual. In some cases (in weakened patients with hymenolepiasis, children, persons with intercurrent diseases), intracellular autoinvasia may occur when dwarf tapeworm eggs are not released into the external environment, but reach maturity in the intestine.
The causative agents of hymenolepiasis cause mechanical damage to the intestinal wall, leading to inflammation, the development of pathogenic microbial flora, disruption of enzymatic processes in the intestine. Also in the pathogenesis of hymenolepiasis, toxic effects on the body of helminth waste products, immunosuppressive effects, sensitization by pygmy tapeworm antigens, irritation of nerve receptors of the mucous membrane of the small intestine and other factors causing characteristic clinical manifestations play a role. The combination of hymenolepiasis with enterobiosis contributes to the long-term course of helminthiasis in children and re-infection. At the same time, hymenolepiasis practically does not occur in the foci of the spread of ascariasis, which is explained by the relative antagonism of ascariids and dwarf tapeworm.
Rat tapeworm (H. diminuta) affects mice, rats and occasionally humans. The adult parasite has a length of 20-60 cm and a width of 2.2-4 mm, a rudimentary proboscis without hooks. The intermediate host of the helminth is insects: fleas, mealworms, cockroaches, etc. People become infected by eating cereals, raw dough, poorly baked bread, on which helminth larvae are present. Intra-intestinal autoinvasion is not characteristic of this form.
Hymenolepiasis symptoms
Approximately 30% have an asymptomatic, subclinical course of hymenolepiasis; in other cases manifest forms of helminthiasis develop with pain, dyspeptic, asthenoneurotic and allergic syndromes. Traumatization of the intestinal mucosa causes dull or sharp abdominal pain, which recurs in the form of seizures daily or after a few days. Dyspeptic manifestations of hymenolepiasis include loss of appetite, heartburn, nausea, diarrhea with an admixture of blood, weight loss. Asthenoneurotic syndrome occurs with dizziness, general asthenia, irritability, headache. Chronic allergosis in hymenolepiasis is characterized by urticaria rash and itching of the skin, vasomotor rhinitis, asthmatic bronchitis, Quincke’s edema.
In the case of intensive invasion, cramping pains, fainting, subfebrility, liver dysfunction, myocardiodystrophy may occur. Children have a more severe course of hymenolepiasis with exhaustion, convulsive seizures, hepatomegaly, severe anemia and hypovitaminosis. The symptoms of hymenolepiasis caused by rat tapeworm are similar to the clinical manifestations of dwarf tapeworm invasion. Hymenolepiasis can aggravate the course of peptic ulcer of the stomach and duodenum, other concomitant diseases, as well as be complicated by mesadenitis.
Diagnostics
When objectively examining patients with hymenolepiasis, attention is drawn to the pallor of the skin, weight loss, arterial hypotension. Hypochromic anemia, accelerated ESR, moderate eosinophilia and leukopenia are detected in peripheral blood.
The diagnosis is confirmed by the detection of helminth eggs or individuals of dwarf or rat tapeworm at different stages of development when examining feces. Since the isolation of eggs occurs cyclically, it is advisable to conduct the analysis three times at intervals of 5 days, as well as a combination of various research methods. In order to increase the effectiveness of the parasitological examination, the patient is prescribed antihelminthic drugs on the eve of the patient, which destroy the segments of the helminth and contribute to the release of more eggs into the intestinal lumen. Serological diagnosis has not been developed. Hymenolepiasis should be differentiated from other intestinal helminthiasis (teniosis, diphyllobothriosis, etc.).
Hymenolepiasis treatment
The features of helminth development and the possibility of autoinvasion require deworming, symptomatic therapy and active preventive measures. For specific therapy of hymenolepiasis, anthelmintic drugs praziquantel (once) or niclosamide (in the form of 3 seven-day, 4 five-day or 6-7 two-day cycles or according to another scheme), male fern extract are used. In between deworming cycles, general restorative therapy (multivitamins, calcium preparations) is carried out. Control stool tests are performed after 15 days and then monthly for six months after the end of the main course of treatment of hymenolepiasis. If helminth eggs are detected, a repeated course of therapy is carried out.
During the treatment of hymenolepiasis, it is important to adhere to a full diet, observe a sanitary and hygienic regime (disinfect care items, change underwear and bed linen in a timely manner, regularly conduct personal hygiene). Patients with negative results of control studies of feces are considered cured within 6 months after the end of the course of therapy for hymenolepiasis.
Anthelmintic therapy leads to recovery in the vast majority of cases. Less common are treatment-resistant forms of hymenolepiasis, as well as a long course of the disease caused by repeated autoinvasion. Prevention of hymenolepiasis requires instilling hygienic skills in children; destruction of rodents, flies, fleas, cockroaches, flour pests. It is important to conduct a regular coprological examination of children, preschool workers, catering, patients of children’s, infectious, gastroenterological hospitals and other population groups, reducing the incidence of enterobiosis in children.
