Infectious diseases are one of the most widespread groups of human pathology. A separate group among them are parasitic diseases. One of these processes is pulmonary paragonimiasis.
What it is?
Paragonimiasis is called an infectious disease caused by a parasite from the group of trematodes - annelids. Mostly lung tissue and muscles are affected with it. The brain is involved in the infectious process quite rarely.
The causative agent of the disease itself - paragonimus westermani (or its other name - "pulmonary fluke") - has an ovoid shape, red-brown color. His whole body is covered with small spines, which allows a more firmly fixed parasitic carrier in the body tissues. There is a suction cup on the abdomen, which also performs a fixing function.
The disease is characterized by certain zones of infection and endemicity. Refers to zoonoses.
With untimely treatment, it can lead to serious complications, some of which are life-threatening.
In what way does infection occur and what features does this parasite have?
Disease spread
Pulmonary trematode is widespread in the middle lane. Most often, outbreaks of this disease are observed in Russia, Asia.
An intermediate host of fluke are small crayfish and arthropods. The final owner - small rodents, muskrats, beavers, wolves, foxes. The final owners also include man.
The pulmonary fluke enters the human body when eating improperly prepared crayfish and crabs.
The eggs of the parasite are excreted from the body with feces and urine. If it enters the environment, some of them die, and some, falling into the water, continue the worm’s development cycle.
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 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 carried out?
Parasite development
How does the pulmonary fluke develop? Its life cycle consists of three stages:
On the first of them, miracidium (nymph) is formed. This stage is the initial one, 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 body of the mollusk, as a result of which it dies, and a large number of cercariae, the second stage of the development of the parasite, enter the water. These larvae possess mobility and penetrate into the body of their intermediate hosts invasively, i.e. through the surface of their body.
The worm at this stage penetrates the body of cancers and crabs, where it develops to metacercaria, the third stage of development. This form is already pathogenic to humans.
In the human intestine, metacercaria leaves its shell and migrates to the lungs, where its fixation and further egg formation take place.
Clinic of the disease
How can one suspect that paragonimiasis has developed? Symptoms of this disease are quite nonspecific, which requires a more accurate and detailed diagnosis.
The disease can occur in the form of several forms - abdominal and pleural pulmonary.
The abdominal form most often occurs with a clinic of enteritis or hepatitis, can lead to the development of parasitic peritonitis relatively favorable course.
The pleuropulmonary form of the disease manifests itself in most patients. There is an increase in temperature to 38 degrees and above, a strong cough with the discharge of purulent bloody sputum with eggs of the parasite. 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 is possible with the development of empyema of pleura or pleurisy.
With the progression of the disease, diffuse pneumosclerosis develops with a deterioration in all functions of external respiration.
Possible rupture of lung tissue with the development of pulmonary hemorrhage.
Complications
The disease itself is quite difficult, however, various complications can occur. How does complicated paragonimiasis proceed? Symptoms of it are manifested as follows.
With a predominance of the abdominal form, intestinal perforation is possible with the development of a clinic of peritonitis and the formation of empyema of the peritoneum and phlegmon.
The pulmonary form is complicated by bleeding, the formation of pleural effusion, pulmonary infarction. The development of cysts in the field of diligence of the heart to the left lung is dangerous.
With hematogenous or lymphogenous spread of the parasite, it can be introduced into various organs and tissues. With paragonimiasis, the brain is rarely affected, but parasitic meningitis and meningoencephalitis may develop.
Paragonimiasis of the lungs can lead to the formation of intrapulmonary cysts. This occurs when, with inadequately performed 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 effect of drugs). Such cysts require surgical intervention.
Diagnosis of the disease
What studies will help determine if a pulmonary fluke has entered the body?
First of all, a general blood test should be done. In it, the most interesting indicators will be ESR, the number of red blood cells and eosinophils.
Patient complaints as well as a carefully collected medical 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 red blood cells decreases with a long ongoing 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.
Examination of sputum makes it possible to identify the eggs of the worm, as well as streaks of blood when bleeding begins.
Treatment
How is this disease treated?
Parasites in the human lungs are quite a serious 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 administered orally.
In addition to it, you can use such tools as Emetin, Chloxil, but the effect of their intake is much less than that of Praziquantel.
The formation of massive cysts requires surgical removal. In some cases, especially if the cysts are large, a pneumonectomy may be required - removal of the entire lung.
With brain damage, only surgical treatment.
Prevention
What should be done so that paragonimiasis does not develop? Prevention may include several activities:
- First of all, the rules for the preparation of freshwater arthropods should be carefully observed. The greatest number of infections with paragonimiasis is due to non-compliance with culinary requirements and norms.
- Partially, the spread of the disease can be affected by cleaning the rivers and streams from the pathogen. It is quite difficult to do this, because as a result of active actions the existing flora and fauna of this area may die.
If there is a suspicion of the presence of a disease (the appearance of cough or other symptoms), for preventive purposes, you can take “Praziquantel” for 4-5 days. However, do not rely on self-medication, as you can only harm yourself. It is better to seek the help of a qualified specialist, so that he determines what kind of disease it is and draw up a competent treatment plan.
Forecast
In general, if the patient addressed at an early stage of the onset of symptoms, and the process did not have time to fully activate, the diagnosis was timely carried out, 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 cysts formed in the lungs, then 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, patients after surgery continue their normal life with some restrictions on physical activity and work.
The most unfavorable prognosis when pathogens enter the brain. If proper measures are not taken in a timely manner, death is possible.