Pulmonary toxoplasmosis

Introduction to pulmonary toxoplasmosis Pulmonary toxoplasmosis (PT) is a lung inflammation caused by Toxoplasmagondii, which invades the human body and causes bloodstream dissemination to most easily invade the central nervous system, and the lungs can also be affected. Although the toxoplasma involving the lung has been reported for a long time, it has not attracted much attention until it is found in the host of cellular immune function defects. basic knowledge The proportion of sickness: 0.01% Susceptible people: no special people Mode of infection: fecal-mouth transmission Complications: pericardial effusion

Cause of pulmonary toxoplasmosis

(1) Causes of the disease

The genus Sporozoite, the genus Coccidia, was first discovered by Nicolle et al. in Tunisia in 1908. The terminal host is a cat or some feline. The intermediate host is very Widely, including mammals (pig, sheep, dogs, cattle, rats, rabbits), poultry (chicken, duck, pigeon-based) and humans, there are five different forms in their developmental stages, namely trophozoites, cysts, cracks Colons, gametophytes and cystic zygotes, the first two are mainly found in the intermediate host, and can also be found in the terminal host. The latter three are only found in the small intestinal mucosal epithelial cells of the terminal host cat. The typical trophozoites are banana-shaped, crescent-shaped or Bow-shaped, one end pointed, the other end is obtuse, (3.5 ~ 8) m × (1.5 ~ 4) m size, Giemsa or Reiter staining cytoplasm is blue, the nucleus is red, mainly seen in the acute infection period, the cyst is Round or elliptical, containing hundreds to thousands of cysts, mainly in the chronic infection stage, schizonts and gametophytes are sexually propagated in the intestinal mucosal epithelial cells of the terminal host cat, producing cystic zygote, Excreted by cat feces, containing two sporangia, and each sporangium Containing 4 sporozoites, elongated, one end pointed, one end blunt, 2 ~ 8m size.

(two) pathogenesis

The disease is a zoonotic disease, cat is the main source of infection, followed by pigs and sheep. The capsules excreted with cat feces can survive in the outside for a long time. The meat or viscera of pigs, sheep and other animals contain cysts. People eat cat water contaminated with water or food or uncooked meat and are infected. Pregnant women can be infected with the fetus through the placenta after infection. It is called congenital toxoplasmosis, immune function inhibition, such as tumor chemotherapy, organ transplantation, In particular, patients with AIDS are susceptible to this disease. Patients with normal immune function are rare. If the body is infected, the sporozoites in the cysts or cysts in the cysts will overflow and pass through the mucosa of the intestinal wall, along with blood or Lymphatic dissemination to the whole body tissue, in which the brain, heart, lymph nodes, lungs are the most vulnerable tissues and organs, the first infection, because the host has not established an immune response, the toxoplasma quickly reaches the organ tissue cells, rapidly proliferating into a rapid colonization The body ruptures the cell, the tachyzoite escapes from the cell and then enters the new cell. When the host has immunity, the toxoplasmic body proliferates slowly into a stimulator in the cell, and the cyst can survive for a long time instead of being a machine. If the body's immune function declines, the capsule will rupture and the worm will escape again, which will form a new spread, so the capsule is a potential source of infection in the host.

The host's defense mechanism mainly passes:

1 specific antibody to promote lysosomal fusion, destroying the toxoplasma;

2 oxygen-mediated respiratory storm episodes are used to kill the toxoplasma;

3 interferon enhances the killing action in macrophages to destroy or destroy the toxoplasma;

4 Monocytes produce nitrogen oxides that regulate or promote oxygen-mediated killing mechanisms. Once the host has a function of clearing the toxoplasma due to abnormalities in the defense mechanisms of different links, it can eventually lead to systemic and pulmonary infections.

Pulmonary toxoplasmosis can be seen by the naked eye. The affected lung is solid, congested, the cut surface is brownish red, the pleura has bleeding points, the bronchial lymph nodes are moderately enlarged, and the pulp in the alveolar cavity is exuded under light microscope. Occasionally, transparent membrane formation or fibrin Purulent exudate, a small amount of neutrophil infiltration, alveolar wall cell proliferation and shedding, toxoplasma trophozoites and (or) cysts in epithelial cells and macrophages, pulmonary interstitial lymphocytes, plasma cell infiltration Fibroblasts and macrophages can be seen, and granuloma changes can also be seen in the lung tissue. The center is banded or localized necrosis, surrounded by lymphocytes and a small number of multinucleated giant cells. It is difficult to find the toxoplasma in the granuloma. Free toxoplasma can be seen in the normal tissues nearby.

Pulmonary toxoplasmosis prevention

1. Strengthen the management of livestock and poultry manure, prevent the water source from being contaminated by livestock (poultry) and avoid mixing humans and animals (avian).

2. Thoroughly treat the patient.

3. Do not eat uncooked animal meat.

4, pregnant women with positive serum test should be treated prophylactically.

Pulmonary toxoplasmosis complications Complications

Combined with heart failure and pericardial effusion.

Symptoms of pulmonary toxoplasmosis Common symptoms Dyspnea, heart failure, convulsions, muscle pain, dry cough, lymph node enlargement, pleural effusion, hepatosplenomegaly, high fever

The clinical manifestations of acquired pulmonary toxoplasmosis may be acute or chronic. In acute cases, most of the initial symptoms are similar, such as headache, myalgia, dry cough, etc. Cough is paroxysmal, and a small number of coughs are mucus or Mucinous blood stasis, chronic clinical manifestations of chronic bronchitis, asthmatic bronchitis or bronchial asthma, pulmonary X-ray manifestations of bronchial pneumonia, atypical pneumonia, pleurisy and cardiovascular disease, 4 types, bronchial pneumonia : lesions are distributed along the bronchus in two, lower lung fields, uneven density, blurred edge of patchy inflammation shadows, widened lung shadow, this type is more common in children and elderly patients; atypical pneumonia type: around the bronchi Qualitative patchy shadow, light density, blurred edges, mainly in the middle and lower lung fields; pleurisy type: signs of pleural effusion; combined with cardiovascular lesions: may have heart failure (acute pulmonary edema), pericardial effusion X-ray signs.

Acquired immunodeficiency syndrome (AIDS) with pulmonary toxoplasmosis, almost all due to disseminated toxoplasmosis involving the lungs, often diffuse pulmonary inflammation, severe symptoms, may have high fever, cough, cyanosis and Difficulty breathing, or rash, lymphadenopathy, meningitis symptoms, diffuse blur or fine nodular infiltrates in the chest X-ray, toxoplasma pneumoniae, cytomegalovirus infection, clinical manifestations More complicated and serious.

Congenital pulmonary toxoplasmosis is caused by acute infection of maternal pregnancy. Neonatal birth can occur with retinal choroiditis, hydrocephalus or cerebellar malformation, brain malformation, convulsions, psychomotor disorders, hepatosplenomegaly, if born In the case of worms, symptoms gradually appear over weeks to months, mainly due to nervous system abnormalities, manifested as retinal choroiditis, strabismus, insomnia, epilepsy, mental exercise or mental retardation or associated with pneumonia.

Examination of pulmonary toxoplasmosis

1. Pathogen detection Direct light microscopy: blood, cerebrospinal fluid, bone marrow, anterior chamber water, sputum, urine, saliva, other exudates, as well as lymph nodes, muscle tissue or other living tissue specimens can be directly smeared or printed, Giemsa or Ritter staining, a typical crescent-shaped toxoplasma trophozoite can be seen inside and outside the cell, and the toxoplasma can also be pear-shaped or oval in the tissue cells; animal inoculation: specimens are inoculated into rats, cotton rats or In the peritoneal cavity and/or brain of the golden hamster, the incubation period is about 4 days. The animals appear inactive, closed eyes, arched back, abdominal enlargement, respiratory distress symptoms, dissection of the lungs, ascites, brain and other tissues for smear staining. Body trophozoites and cysts; protozoan culture: chicken embryo culture and tissue culture method, the former specimens are inoculated on chicken chorioallantoic membrane for 10 to 12 days, incubated for 6 to 7 days (35 ° C), if positive, urine The edema of the capsule is turbid and there is a yellow-white necrotic foci.

2. Sabin-Feldman dye test: Sabin was mixed with normal toxin in 1948, and the basic methylene blue (methylene blue) stained the worm body deeply, but mixed with the immune serum and stained very much. Light or non-staining, suggesting that the test has high sensitivity and specificity. Others such as indirect fluorescent antibody, indirect hemagglutination and complement fixation test have certain diagnostic reference value; intradermal test also has high specificity for chronic diseases. Cases have a screening effect and have diagnostic value in epidemiological investigations.

3, X-ray examination of the lungs showed bronchial pneumonia, atypical pneumonia, pleurisy and cardiovascular disease, four types, bronchial pneumonia type: lesions are distributed along the bronchus in two, lower lung field, uneven density, blurred edges Patchy inflammatory shadows, widened lung hilars, this type is more common in children and elderly patients; atypical pneumonia type: fluffy shadows around the bronchi, the density is light, the edges are blurred, mainly in the middle and lower lung fields ; pleurisy type: signs of pleural effusion; combined with cardiovascular disease type: may have heart failure (acute pulmonary edema), X-ray signs of pericardial effusion.

Diagnosis and diagnosis of pulmonary toxoplasmosis

In view of the lack of specificity of PT clinical manifestations, the diagnosis is difficult. The diagnosis should be judged by the combination of medical history, clinical manifestations, staining test, immunological examination and intradermal test. Sputum, pleural effusion, cerebrospinal fluid and other body fluids, or living tissue. Pathological examination found toxoplasma worm body, can be diagnosed, staining test, complement binding test, intradermal test or serum antibody test positive, have diagnostic reference value.

Clinically common in the identification of infectious mononucleosis and mycoplasmal pneumonia.

1. Infectious mononucleosis is an acute self-limiting infectious disease caused by EBV virus, a contact infectious virus (Epstein-Barr virus). Its clinical features are fever, pharyngitis, hepatosplenomegaly, enlarged peripheral blood lymphocytes and abnormal lymphocytes, positive heterophilic agglutination test, anti-EBV antibodies appear in the body after infection. Adolescents and young adults are more likely to occur (12 to 40 years old).

2. Mycoplasma pneumoniae is an acute lung infection caused by mycoplasma pneumoniae, which is mainly caused by interstitial lesions. Because of the clinical manifestations of such pneumonia, there are significant differences between pneumonia caused by common bacteria such as Streptococcus pneumoniae, and -lactams. Antibiotics and sulfonamides are ineffective, so the pneumonia caused by Legionella pneumophila, Chlamydia pneumoniae and Rickettsia and other atypical pathogens is collectively referred to as "primary atypical pneumonia". In recent years, atypical pathogens, especially Mycoplasma pneumoniae, have been found to be the main pathogens of community-acquired pneumonia.

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