Infectious diseases are one of the most widespread groups of human pathology. Parasitic diseases form a separate group among them. One such process is lung paragonimiasis.
What is this?
Paragonimiasis is an infectious disease caused by a parasite from the group of trematodes - annelids. It affects mainly the lung tissue, muscles. The brain is rarely involved in the infectious process.
The causative agent of the disease - paragonimus westermani (or its other name - "lung fluke") - has an ovoid shape, red-brown color. Its entire body is covered with small spines, which allows it to be more firmly fixed in the tissues of the organism of the parasite carrier. There is a suction cup on the abdomen, which also performs a fixing function.
The disease is characterized by certain areas of infection and endemicity. Refers to zoonoses.
If delayed treatment can lead to severe complications, some of which are life-threatening.
How does infection occur and what features does this parasite have?
Disease spread
Pulmonary fluke is widespread in the middle lane. Most often, outbreaks of this disease are observed in Russia, Asia.
The intermediate host of the fluke are small crayfish and arthropods. The final owner is small rodents, muskrats, beavers, wolves, foxes. Humans also belong to the final hosts.
The lung fluke enters the human body by eating improperly cooked crayfish and crabs.
The eggs of the parasite are excreted from the body with feces and urine. When released into the external environment, some of them die, and some, falling into the water, continue the cycle of development of the worm.
In the human body, the worm is localized mainly in the lung tissue - its small bronchioles. From there, spreading through the lymphatic vessels, it can also penetrate into other departments and organs of the human body, which leads to a complicated course of the infectious process.
How is the life cycle of this pathogen?
Development of the parasite
How does a lung fluke develop? Its life cycle consists of three stages:
A miracidium (nymph) is formed on the first of them. This stage is initial, and the parasite passes it after leaving the egg. In water, miracidium penetrates the body of the first intermediate host, a freshwater mollusk. During the first five months, asexual reproduction occurs in the bodymollusk, as a result of which it dies, and a large number of cercariae, the second stage of development of the parasite, enter the water. These larvae are mobile and enter the body of their intermediate hosts invasively, i.e. through the surface of their body.
The worm at this stage penetrates into the body of crayfish and crabs, where it develops to a metacercaria - the third stage of development. This form is already pathogenic for humans.
In the human intestine, the metacercariae emerge from their shell and migrate to the lungs, where it is fixed and further egg formation takes place.
Disease clinic
How can one suspect that paragonimiasis has developed? The symptoms of this disease are rather non-specific, which requires a more accurate and detailed diagnosis.
The disease can occur in several forms - abdominal and pleuropulmonary.
The abdominal form most often occurs with a clinic of enteritis or hepatitis, can lead to the development of parasitic peritonitis with a relatively favorable course.
The pleuropulmonary form of the disease manifests itself in most cases. There is an increase in temperature up to 38 degrees and above, a strong cough with discharge of purulent bloody sputum with parasite eggs. There is also a clinic of pneumonia, pleurisy.
When the parasite is located at the outer edges of the lungs, the formation of parietal cysts with the development of pleural empyema or pleurisy is possible.
As the disease progresses, diffuse pneumosclerosis develops with a deterioration in all functionsexternal respiration.
Possible rupture of the lung tissue with the development of pulmonary bleeding.
Complications
The disease itself is quite difficult, but there may be various complications. How does complicated paragonimiasis proceed? Its symptoms are as follows.
With the predominance of the abdominal form, intestinal perforation is possible with the development of a peritonitis clinic and the formation of peritoneal empyema and phlegmon.
The pulmonary form is complicated by bleeding, pleural effusion, pulmonary infarction. It is dangerous to develop cysts in the area of heart attachment to the left lung.
With hematogenous or lymphogenous spread of the parasite, it can enter various organs and tissues. The brain is rarely affected in paragonimiasis, but parasitic meningitis and meningoencephalitis may develop.
Paragonimiasis of the lungs can lead to the formation of intrapulmonary cysts. This happens when, with inadequately conducted anthelmintic therapy, the worm, in order to avoid the effects of drugs, forms a dense calcified capsule around itself, which allows you to wait out adverse conditions (in this case, the action of drugs). Such cysts require surgical intervention.
Diagnosis of disease
What research will help determine that a lung fluke has entered the body?
First of all, you should conduct a study of the general blood test. In it, the most interesting indicators will be ESR,the number of erythrocytes and eosinophils.
Complaints from the patient and a thorough history (eating crayfish or crabs, using running water from rivers in endemic areas) will also help.
With helminthiasis, eosinophils and ESR will be increased. The level of erythrocytes decreases with a long-term process.
Of the instrumental methods, fluorography is the best. It allows you to determine the presence of a cavity formation in the lung tissue, to identify its localization and size. Based on the image data, a diagnosis is made.
Sputum examination makes it possible to identify worm eggs, as well as streaks of blood when bleeding begins.
Treatment
How is this disease treated?
Parasites in the human lungs are a serious enough problem, so treatment should begin as early as possible and aim to destroy the helminth.
The main drug used to treat paragonimiasis is Praziquantel. Its dose is calculated based on the proportion of 60-70 mg of the drug per kilogram of body weight. This remedy for parasites is prescribed in three doses after each meal. The drug is used orally.
Besides it, you can use such means as “Emetine”, “Chloxil”, however, the effect of taking them is much less than that of “Praziquantel”.
When massive cysts form, surgical removal is required. In some cases,especially if the cysts are large, a pneumonectomy may be required - the removal of the entire lung.
In case of brain damage, treatment is only surgical.
Prevention
What should be done to prevent the development of paragonimiasis? Prevention can include several activities:
- First of all, you should carefully follow the rules for cooking freshwater arthropods. The largest number of infections with paragonimiasis falls precisely on non-compliance with culinary requirements and norms.
- The spread of the disease can be partially controlled by clearing rivers and streams of the pathogen. It is quite difficult to do this, since as a result of active actions, the existing flora and fauna of this area may also die.
If there is a suspicion of a disease (the appearance of a cough or other symptoms), as a preventive measure, you can take Praziquantel for 4-5 days. However, do not rely on self-treatment, as you can only harm yourself. It is better to seek help from a qualified specialist so that he determines what kind of disease it is and draws up a competent treatment plan.
Forecast
In general, if the patient applied at an early stage of the onset of symptoms, and the process did not have time to fully activate, the diagnosis was carried out in a timely manner, and an adequate treatment plan was prescribed, then the prognosis is quite favorable. Many people are completely cured of paragonimiasis.
If the process was started, and incysts form in the lungs, the prognosis worsens somewhat. Small cysts may not have a significant effect on the body; large ones will require their removal, which, as a result, can lead to disability of the patient. In general, after surgery, patients continue normal life activities with some restrictions on physical activity and work.
The most unfavorable prognosis is when pathogens enter the brain. If proper measures are not taken in a timely manner, a fatal outcome is possible.
