Pulmonary echinococcosis is a form of anthropozoon infection caused by the larva of the echinococcal tapeworm and leading to a specific cystic lesion of the lung tissue. Manifestations of pulmonary echinococcosis can be chest pain, shortness of breath, persistent cough, urticaria rash and itching; with a complicated course – copious sputum with an admixture of blood and pus, fever, respiratory disorders, severe anaphylactic reactions. The diagnosis is established using radiography and CT of the lungs, sputum microscopy, serological blood analysis. With pulmonary echinococcosis, removal of a parasitic cyst, lung resection, lobectomy in combination with antiparasitic therapy are performed.
B67.1 Lung invasion caused by Echinococcus granulosus
Pulmonary echinococcosis is the most dangerous helminthiasis that develops when infected with eggs of the tapeworm – echinococcus, accompanied by the formation of parasitic cysts in the pulmonary parenchyma. Lung invasion is observed in 15-20% of all cases of echinococcosis, 70-80% is due to liver damage (echinococcosis of the liver), the rest is the heart, brain and other internal organs. Disease is most often registered in regions with a dry hot climate and developed cattle breeding: countries of South America, North Africa, Australia and N. New Zealand, in the southern part of Europe, the USA, Ukraine, Moldova, Central and South Asia.
Causes of pulmonary echinococcosis
The causative agent of pulmonary echinococcosis is the larva of the tapeworm Echinococcus (Echinococcus granulosus), belonging to the cestodes. Mature individuals parasitize in the small intestines of canine and feline animals – dogs, wolves, foxes, arctic foxes, etc. In the larval stage (parasitic cyst), echinococci live in the tissues of intermediate hosts – paired and ungulates (sheep, cows, horses, deer, pigs) and humans.
A person becomes infected with echinococcus eggs released from the feces of sick animals, usually through contact with wool, milking, shearing sheep, dressing hides and alimentary way when eating unwashed infected vegetables, herbs, water. Aerogenic infection is rarely realized when dust is inhaled during hay harvesting and agricultural work. Echinococcus embryos are hematogenically dispersed from the intestine to the liver, lungs and throughout the body. With respiratory infection, oncospheres are fixed on the walls of the bronchi, then penetrate into the lung tissue, forming vesicular structures.
Echinococcus is capable of growth and endless reproduction due to brood capsules of the inner layer, reproducing scolexes and forming daughter bubbles in the cyst cavity. Due to the high elasticity of the lung tissue, the cyst gradually grows, reaching a large volume in a few years. Giant cysts with a diameter of 10-20 cm can contain several liters of fluid. In the lung, the larva of echinococcus can remain viable for many years and even decades (20 years or more). Pulmonary echinococcosis can occur uncomplicated and with complications (calcification, suppuration and rupture of the cyst).
The cyst of echinococcus is limited by a dense shell consisting of outer (cuticular) and inner (germinal) layers, and is filled with yellowish liquid contents. pulmonary echinococcosis usually has a single–chamber (hydatidose), rarely a multi-chamber, form.
The effect of a growing echinococcal cyst on the body is associated with a traumatic effect on the surrounding tissues, irritating and sensitizing effect of antigens and metabolic products of the parasite. Pulmonary echinococcosis is characterized by the development of allergic reactions of delayed and immediate type (eosinophilia, urticaria, anaphylaxis), with multiple larvae at a late stage – immunosuppression. Compression of small bronchi by a cyst significantly disrupts their function, leads to the formation of lung atelectasis, bronchial atrophy. Fibrosis of the lung tissue develops around the cyst.
Suppuration of an echinococcal cyst causes the death of the larva and the destruction of the bladder, an inflammatory process in the surrounding tissues. Emptying of the cyst into the bronchus (90% of cases), blood vessel, pleural or abdominal cavity, pericardium contributes to the seeding and development of numerous metastatic foci in healthy lobes of the lungs and other organs, the development of local and general toxic-anaphylactic reactions.
When a cyst breaks into the bronchus, the parasite often dies, and fragments of the capsule are released through the respiratory tract with sputum and pus when coughing. The outcome may be complete healing of the fibrous cavity in the lungs, the formation of a persistent lung cyst, chronic purulent inflammation. A breakthrough into the pleural cavity leads to a collapse of the lung, an increase in respiratory failure. Calcification of echinococcus is usually observed with a violation of its development, the death of the larva and the complete recovery of the patient.
Pulmonary echinococcosis can be primary and secondary (metastatic), develop in any part of the lung, but mainly affects the lower lobes. In this case, unilateral or bilateral, single or multiple echinococcal cysts may form, having a small (up to 2 cm), medium (2-4 cm) or large (4-8 cm or more) size.
Symptoms of pulmonary echinococcosis
In clinical pulmonology, there are 3 stages of pulmonary echinococcosis. In the initial period of the disease, from the moment of fixation of the larva in the lungs to the first signs of helminthiasis, a latent course is noted. The slow growth of the cyst does not bother the patient, sometimes there may be a malaise of an unclear nature, increased fatigue.
The stage of clinical manifestations of pulmonary echinococcosis is usually observed 3-5 years after invasion with a significant volume of cyst. There is pain in the chest of a dull nature, shortness of breath, persistent cough (first dry, then wet, with streaks of blood), dysphagia. Patients with pulmonary echinococcosis may have allergic phenomena in the form of itching, urticaria rash, bronchospasm. With echinococcosis, lung atelectasis may develop.
The terminal stage of pulmonary echinococcosis is characterized by severe and life-threatening complications. Suppuration of the cyst proceeds with symptoms of a lung abscess. The breakthrough of the bladder into the bronchus is characterized by a sharp paroxysmal cough with copious watery sputum with an admixture of blood and / or pus, fragments of the cystic membrane and small daughter capsules; cyanosis, asphyxia, severe allergic reactions.
The breakthrough of the cyst into the pleural cavity is accompanied by the development of pleurisy, a sharp deterioration in well-being, acute pain in the affected area, chills, a jump in temperature, respiratory disorders, the risk of pyopneumothorax and pleural empyema, anaphylactic shock and death. When the cyst is emptied into the pericardium, a cardiac tamponade occurs. Clinical symptoms of pulmonary echinococcosis can be combined with disorders caused by extrapulmonary localization of parasitic cysts.
In the diagnosis of pulmonary echinococcosis, X-ray methods, sputum microscopy, general blood analysis, serological examination are used. When collecting anamnesis, the facts of being in regions that are epidemiologically unfavorable for echinococcosis, the presence of work related to animal husbandry, hunting, and processing animal skins are important.
With a very large echinococcal bladder, you can notice the protrusion of the affected part of the chest wall with flattening of the intercostal spaces. In the area of the projection of the echinococcal cyst, the dulling of the percussion sound is determined. With perifocal inflammation, wet wheezing is detected; when the cyst is emptied, breathing becomes bronchial. Physical data are more pronounced with the development of complications.
- X-ray. During the latent period of echinococcosis, one or more large rounded homogeneous, clearly defined shadows are detected on lung radiographs, changing their configuration during respiratory movements. With CT, the cystic nature of the lesion is obvious, the presence of a cavity with a horizontal fluid level and perifocal infiltration (pronounced with suppuration) is determined, sometimes calcification.
- Laboratory test. Eosinophilia is detected in the blood, with suppuration of the cyst – leukocytosis, increased ESR. Microscopy of sputum sediment, which makes it possible to detect scolexes, fragments of the cyst shell when a cyst breaks through, confirms the parasitic nature of the disease. Serodiagnostics (ELISA) is performed in order to detect specific antibodies to echinococcus in the blood.
The differential diagnosis of echinococcosis is carried out with tuberculosis, benign lung tumors, bacterial abscess and hemangioma of the lungs. Bronchoscopy and diagnostic thoracoscopy may be performed.
Treatment for pulmonary echinococcosis
The main method of complete cure is surgical intervention. With small superficial cysts, an “ideal” echinococcectomy is performed without opening the parasite capsule. The cavity formed inside the fibrous membrane in the lung is treated with formalin solutions, hypertonic and alcohol solution, antiseptics, and then sutured.
In the case of a large or deeply located cyst, its preliminary puncture and careful maximum aspiration of the contents are carried out using a closed system with an electric pump. After antiseptic treatment, the chitin capsule is excised separately or together with the fibrous membrane (so-called “radical” echinococcectomy). The large cavities remaining after the operation in the lung are eliminated by taking kapitonage or using cyanoacrylate glue. With pulmonary echinococcosis, it is possible to perform a wedge-shaped lung resection, segmentectomy, lobectomy. With small (up to 3 cm) cysts, as well as before and after surgery for pulmonary echinococcosis, antiparasitic (scolecidal) drugs are used.
Prognosis and prevention
The prognosis of pulmonary echinococcosis with timely radical surgical intervention is usually favorable. The formation of intraoperative metastatic foci is fraught with a recurrence of helminthiasis with multiple lesions. Prevention of pulmonary echinococcosis consists in observing the rules of personal hygiene, deworming of pets, sanitary control of the conditions of keeping and slaughter of livestock, trapping stray animals.