Helminthiasis

Helminthiasis (helminthic infestation): causes, symptoms, diagnosis and treatment methods.

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Helminthiases are diseases of humans, animals and plants caused by parasitic worms (helminths).

Causes of helminthiasis

Currently, more than 70 species of the 250 known helminths that parasitize the human body are found in our country.The most common are roundworms (roundworm, pinworm, trichinella, whipworm), tapeworms (pork, bovine and dwarf tapeworms, broad tapeworm, echinococci) and flukes (liver and cat flukes).

Helminths are characterized by developmental stages: eggs → larvae → sexually mature forms.

Helminth infection most often occurs after their eggs and/or larvae enter the body.Depending on the infection mechanism and transmission routes, helminthiasis is divided into: geohelminthiasis, biohelminthiasis and contact helminthiasis.Geohelminths develop without intermediate hosts, biohelminths develop with a sequential change of one, two or three hosts, contact helminths are transmitted by contact.

Pork tapeworm, bovine tapeworm, echinococcus and other types of worms develop with a successive change of one, two or three hosts.Intermediate hosts can be fish, molluscs, crustaceans and insects.A person becomes infected with these helminths when eating food that has not undergone complete heat treatment:

• beef infected with bovine tapeworm larvae;
• pork affected by Finnish pork tapeworm;
• lightly salted and raw fish with opisthorchis or broad tapeworm larvae;
• raw water or vegetables and fruits treated with this water.

Whipworms, roundworms, hookworms and necator develop without intermediate hosts.The eggs and larval forms of these parasites enter the soil with feces.If personal hygiene rules are not observed, they penetrate the body of a new host.

By contact - that is, through personal contact between a healthy person and an infected person, through the use of shared utensils, personal hygiene products, bedding and through inhalation of dust in a room where an infected person is - enterobiasis (pathogen - pinworm) and hymenolepiasis (pathogen - dwarf tapeworm) are transmitted.In the case of enterobiasis, self-infection often occurs.

Helminths of a certain type parasitize in certain organs, causing various helminthiasis:

• in the large intestine - pigs, cattle, dwarf tapeworms, nematodes (hookworms, roundworms, strongyloids), pinworms, whipworms.From the intestinal lumen, pork tapeworm larvae can enter the bloodstream and spread throughout the body, settling in adipose tissue, muscle vessels, eye chambers and the brain;
• in the liver and bile ducts - trematodes (opisthorchis, clonorchis, fasciola).Echinococcal cysts are mainly located in the liver, and after their rupture, daughter bubbles can be found in the mesentery, peritoneal layers, spleen and other organs;
• in the respiratory organs - echinococci, alveococci, lungworms, causing paragonimiasis;
• in the nervous system - schistosomiasis, paragonimiasis, echinococcosis and alveococcosis;
• in the organs of vision - onchocerciasis, loiasis, complicated forms of taeniasis;
• in the circulatory system - necatoriasis, schistosomiasis, diphyllobothriasis;
• in the lymphatic system - filariasis, trichinosis;
• on the skin and subcutaneous tissue - hookworm, onchocerciasis, loiasis, larval stage of schistosomiasis;
• in the skeletal system - echinococcosis;
• in skeletal muscles - trichinosis, cysticercosis of muscle tissue.

The lifespan of helminths in the body of the definitive host can be different, it depends on the type of parasite and varies from several weeks (pinworms) to several years (tapeworm) and decades (fasciola).

Disease classification

There are two types of worms that parasitize humans:

• Nemahelminthes – roundworms, class Nematoda;
• Flatworms are flatworms, which include the class Cestoidea - tapeworms, Trematoda - the class worms.

Depending on the routes of propagation of parasites and the characteristics of their biology, they are distinguished:

• biohelminthiasis;
• geohelminthiasis;
• come into contact with helminthic infections.

Helminthiasis symptoms

Helminths have different effects on the human body:

• antigenic effects, when local and general allergic reactions develop;
• toxic effect (helminth residues cause malaise, weakness, dyspeptic symptoms);
• traumatic effect (when parasites attach to the intestinal wall, blood supply is disrupted with necrosis and subsequent atrophy of the mucous membrane; absorption processes may be disrupted; mechanical compression of tissues by helminths);
• secondary inflammation as a result of the penetration of bacteria after the migration of helminth larvae;
• violation of metabolic processes;
• as a result of absorption of blood by some helminths, anemia occurs;
• neuro-reflex effect - irritation of nerve endings by helminths causes bronchospasm, intestinal dysfunction, etc.;
• psychogenic effect, manifested by neurotic states, sleep disturbances;
• immunosuppressive effect.

Helminthiases are characterized by stages of development.Each stage is characterized by its own clinical symptoms.

In the initial acute phase, helminths most often do not yet release eggs, there is sensitization of the organism (production of antibodies, release of inflammatory mediators, increased permeability of the vascular wall) and trauma to the organs through which the larvae migrate.Clinical symptoms may be absent, but in some cases the disease may occur with pronounced clinical manifestations.The acute phase lasts 1 to 4 months, sometimes 8 to 10 months or longer.

Complaints of patients in the acute phase:

• increase in temperature from several days to two months (low-grade fever or above 38ºС, accompanied by chills, severe weakness and sweating);
• recurrent itchy rashes;
• local or generalized edema;
• enlargement of regional lymph nodes;
• pain in muscles and joints;
• cough, asthma attacks, chest pain, prolonged catarrhal symptoms, bronchitis, tracheitis, symptoms simulating pneumonia, asthmatic syndrome, hemoptysis;
• abdominal pain, nausea, vomiting, stool disorders.

At the end of this phase of helminthic infections, acute allergic phenomena gradually subside and the chronic phase clinic has not yet had time to develop.

The acute stage becomes subacute as the “young” helminths gradually mature.Then comes the chronic stage, corresponding to the development of the parasites into sexually mature individuals.The clinical picture develops against the background of the toxic effect of helminth residues, the traumatic effect of helminths on organs (hookworm, trichuriasis, etc.), mechanical effects (an echinococcal cyst in the liver grows, compresses neighboring organs; cysticerci - in the brain), a secondary inflammatory process (duodenitis is observed in strongyloidiasis), metabolic disorders (hypo- or avitaminosis), functional disorders of the stomach and duodenum, secondaryimmunodeficiencies, etc.

Symptoms depend on the organs where the helminths parasitize, their size and quantity.

Tointestinal helminthiasisThe following syndromes are characteristic:

• dyspeptic (stomach discomfort, feeling of fullness after eating, early satiety, bloating, nausea);
• painful;
• asthenoneurotic (feeling of extreme fatigue, increased nervous excitability and irritability).

Enterobiasis is characterized by nocturnal perianal itching.With massive roundworm infestation, there may be intestinal obstruction, pancreatitis, obstructive jaundice.

Intestinal cestoses(taeniarinhoz, diphyllobothriasis, hymenolepiasis, taeniasis and others) are asymptomatic or with a small number of symptoms (with symptoms of dyspepsia, pain, anemia).

Liver flukes(fascioliasis, opisthorchiasis, clonorchiasis) causes:

• chronic pancreatitis;
• hepatitis;
• cholecystocholangitis;
• neurological disorders.

Hookworm diseasemanifested by asthenovegetative syndrome (weakness, fatigue, pallor of the skin) due to the development of iron deficiency anemia.

Filariasis is characterized by an allergic syndrome of varying severity and regional lymphadenitis.

Urogenital schistomiasisIt is manifested by the appearance of blood at the end of urination, frequent urge to urinate, pain when urinating.

Alveococcosis, cysticercosis, echinococcosismay remain asymptomatic for a long time.At a later stage, suppuration or rupture of cysts containing parasites leads to anaphylactic shock, peritonitis, pleurisy and other serious consequences.

For diseases caused by parasitism of migratory larvaezoohelminthswhen a person is not the natural host, distinguish between cutaneous and visceral forms.The cutaneous form is caused by the penetration of certain animal helminths under human skin: schistosomes of waterfowl (trematodes), hookworms of dogs and cats, strongyles (nematodes).When a person comes into contact with soil or water, helminth larvae penetrate the skin.There is a burning, tingling or itching sensation at the site of the helminth's introduction.There may be a short-term fever and signs of general malaise.After 1-2 weeks (less often 5-6 weeks), recovery occurs.

The visceral form develops as a result of ingestion of helminth eggs with water and food.At the beginning of the disease, malaise and allergic exanthema (skin rash) may occur.In the human intestine, larvae hatch from helminth eggs, penetrate the intestinal wall into the blood, reach the internal organs, where they grow and reach 5 to 10 cm in diameter, compress the tissues and disrupt the functioning of the organs.When tapeworm larvae (cysticerci, tsenura) are located in the membranes and substance of the brain, headache, signs of cerebral hypertension, paresis and paralysis, and epileptiform convulsions are observed.Larvae can also be located in the spinal cord, eyeball, serous membranes, intermuscular connective tissue, etc.

The result of helminthiasis can be complete recovery with the elimination of helminths or the development of irreversible changes in the host's body.

Diagnosis of helminthiasis

The diagnosis of helminthiasis is established on the basis of a combination of complaints, information received from the patient about the course of the disease, data from laboratory methods and instrumental examinations.

In the acute phase of helminth infections, a blood reaction occurs to the presence of a helminth in the body, therefore the following studies are recommended:

• clinical blood test: general analysis, leukoformula, ESR (with blood smear microscopy in the presence of pathological changes);
• biochemical blood test:
• total protein, albumin, protein fractions; 
• assessment of renal function indicators (urea, creatinine, glomerular filtration);
• assessment of liver function indicators (bilirubin, ALT, AST, alkaline phosphatase);
• pancreatic alpha-amylase;
• assessment of carbohydrate metabolism: glucose (in the blood), glucose tolerance test with determination of glucose in venous blood on an empty stomach and after exercise after 2 hours.

The following biological materials can be examined for the presence of helminths: feces, blood, urine, duodenal contents, bile, sputum, muscle tissue, rectal and perianal mucus.

Since helminths are not excreted in feces at any stage of their development, it is recommended to donate feces three times - every 3-4 days.

• Analysis of feces for helminth eggs.
• Test for enterobiasis (moth eggs), smear.
• Microscopic examination of feces to detect eggs of the enterobiasis pathogen Enterobius vermicularis (pinworms).
• Test for enterobiasis (moth eggs), spatula.
• The analysis is necessary if pinworm infection is suspected, as well as during hospitalization and medical records.
• Analyzes for kindergarten and school.

The child examination program must be completed before entering kindergarten or school.The results of these studies are necessary to obtain a medical certificate in accordance with form 026U approved by the Ministry of Health of the Russian Federation.

Carry out immunological studies - determination of specific antibodies to helminths:

• IgG roundworm antibodies;
• anti-Echinococcus IgG;
• IgG antibodies to Toxocar antigens;
• anti-Opisthorchis felineus IgG (IgG class antibodies to cat worm antigens);
• IgG antibodies to Trichinella antigens;
• antibodies against the causative agent of anisakiasis (nematodes of the genus Anisakis), IgG;
• antibodies to the causative agent of clonorchiasis, IgG;
• Antibodies to Strongyloides stercoralis, the causative agent of strongyloidiasis, IgG.

A test that aims to detect IgG antibodies against the causative agent of strongyloidiasis is used for the early serological diagnosis of strongyloidiasis in cases of clinical suspicion (eosinophilia, serpentine skin lesions, pulmonary or gastrointestinal symptoms) of this disease.

In difficult cases, the following studies may be recommended:

• simple x-ray of the thoracic organs;
• comprehensive ultrasound examination of abdominal organs (liver, gallbladder, pancreas, spleen);
• Computed tomography of the abdominal cavity and retroperitoneum;
• Computed tomography of the chest and mediastinum;
• Computed tomography of the brain and skull.

Which doctors should I contact?

If you suspect helminthiasis, consult a therapist or general practitioner and, with your child, a pediatrician.

If surgical treatment is indicated, the patient is referred to the surgeon.

Helminthiasis treatment

Most people with helminth infections do not require hospitalization.Patients with tissue helminthiasis, regardless of severity, and patients with a severe and complicated course of the disease are treated in the hospital.

Therapy is carried out with anthelmintic drugs.The frequency of administration and dosage of the medication depend on the patient's age and body weight and are established by the doctor.

Desensitization, detoxification therapy and vitamin therapy may be indicated.To reduce the temperature, non-steroidal anti-inflammatory drugs are prescribed, for an allergic reaction and itching - antihistamines, for severe edema - diuretics.In severe cases, hormonal medications are required.

The presence of helminths in organs and tissues may be an indication for surgical treatment.

Complications

• Bronchial asthma.
• Pneumonia.
• Bowel cancer.
• Cirrhosis.
• Portal hypertension.
• Gastrointestinal bleeding.
• Ascites.
• Hepatitis.
• Liver abscess.
• Peritonitis.
• Allergic myocarditis.
• Meningoencephalitis.
• Chronic glomerulonephritis.
• Chronic kidney disease.
• Hemostasis disorders.
• Vision loss.

Prevention of helminthiasis

Preventive measures aimed at preventing helminth infection include:

• compliance with personal hygiene rules (use of individual towels, personal hygiene items and other accessories for daily use);
• use only good quality water in everyday life;
• regular vaccination and deworming of pets;
• Thorough washing of vegetables, fruits and berries before consumption;
• sufficient heat treatment of meat and fish products.

With regular contact with pets, children in children's groups, contact with the land, fishing or hunting hobbies, frequent trips to exotic countries, prevention can be carried out through the use of medications.Drug prophylaxis should be taken by the whole family twice a year (for example, in spring and autumn).

IMPORTANT!

The information in this section cannot be used for self-diagnosis and self-treatment.In case of pain or other exacerbation of the disease, diagnostic tests should only be prescribed by the attending physician.To make a diagnosis and prescribe treatment correctly, you must contact your doctor.