pulmonary capsular histoplasmosis
Introduction
Introduction to pulmonary capsular histoplasmosis Pulmonary capsular histoplasmosis is a manifestation of fungal disease caused by capsular histoplasmosis in the lungs. The lungs are primary infections, mostly asymptomatic or self-limiting respiratory infections. Disperse, mainly involving the reticuloendothelial system. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: respiratory failure
Cause
Cause of pulmonary capsular histoplasmosis
Causes:
The capsular histoplasma is a biphasic fungus. It is hyphal in the natural environment and has large and small spores. On the host tissue and nutrient-rich medium, the yeast type has a transparent band similar to the capsule in vitro.
The cytoplasmic spores are inhaled through the respiratory tract, most of which are eliminated by the body's defense mechanism. The spores that reach the alveoli proliferate and transform into yeast type, causing neutrophils and macrophages to aggregate. The yeast is swallowed by macrophages, but not killed. , still able to reproduce and reach the blood circulation through the hilar lymph nodes.
Pathogenesis:
The cytoplasmic spores are inhaled through the respiratory tract, most of which are eliminated by the body's defense mechanism. The spores that reach the alveoli proliferate and transform into yeast type, causing neutrophils and macrophages to aggregate. The yeast is swallowed by macrophages, but not killed. It can still reproduce and reach the blood circulation through the hilar lymph nodes. After inhalation of spores for 2 to 3 weeks, macrophages kill fungi with the production of cellular immunity, and form granulomas or caseous necrosis with the enhancement of inflammatory reaction, and the immune function is normal. Most of the patients' lesions are confined to the lungs. If the immune function is low or the amount of infectious bacteria is too large, it can lead to progressive disseminated histoplasmosis, and the healing mode is calcification or fibrosis.
According to epidemiological data, clinical manifestations, X-ray signs and serological tests can be used for diagnosis. The diagnosis depends on fungal culture or histological examination to confirm the presence of pathogenic bacteria.
Prevention
Pulmonary capsular histoplasmosis prevention
The hyphae type of this strain is highly infectious, and laboratory work should be taken for prevention. People who are new to the epidemic area should pay special attention to prevent infection due to poor immunity. In the bird cages, chicken nests and bat caves, there is often contamination of the bacteria, and prevention should be taken. Main measures: 1.3% formaldehyde is used for disinfection in contaminated areas. 2. Prophylactic antifungal treatment.
Complication
Pulmonary capsular histoplasmosis complications Complications, respiratory failure
Often died of respiratory failure.
Symptom
Pulmonary capsular histoplasmosis symptoms common symptoms high fever jaundice flu-like symptoms pulmonary fibrosis night sweats dyspnea hemoptysis hypothermia chills lymph node enlargement
The incubation period is 9 to 14 days.
1. Acute type: Most normal people do not have symptoms after infection, and a few (mostly children) manifest as fever, cough, headache and other upper respiratory tract infections or flu-like symptoms, and some may have joint pain - nodular erythema - polymorphic erythema The levy lasts about 1 week, and the lungs have few signs. The chest radiograph can be abnormal. It can also manifest as single or multiple nodular infiltration shadows. The hilar lymph nodes are swollen. After a large number of inhaled spores, there may be chills and high fever. Cough, cough mucus, dyspnea, hemoptysis and other symptoms of pneumonia, chest radiographs showed flaky infiltration shadow or lung consolidation, often accompanied by hilar lymphadenopathy, occasional pleural reaction, this type of disease is about 1 week, mostly It can be self-healing, and a small number of them continue to progress. Pneumonia is also a benign pass.
2. Chronic cavities: mainly occur in patients with emphysema, tuberculosis, etc. or destructive lung structures. Because of abnormal cavities, pathogens can escape the interference of human immune mechanisms, better reproduction, clinical manifestations and tuberculosis are very similar, low fever, Night sweats, weight loss, cough, cough and sputum, gradually appear dyspnea, this type except for a small number of patients self-healing, most progress, eventually leading to pulmonary fibrosis, often died of respiratory failure.
3. Progressive dissemination type: This type is rare, occurs in immunosuppressed patients or the elderly, children, mainly spread to the reticuloendothelial system, patients with systemic symptoms, often high fever, difficulty breathing, hepatosplenomegaly, lymph nodes Swollen, jaundice, anemia, oral and gastrointestinal ulcers, endocarditis, meningitis and Addison's disease, X-ray showed miliary shadows or scattered nodular lesions in both lungs, similar to miliary Tuberculosis, young children or AIDS patients progressed rapidly, and other patients progressed relatively slowly with a mortality rate of 80%.
According to epidemiological data, clinical manifestations, X-ray signs and serological tests can be used for diagnosis. The diagnosis depends on fungal culture or histological examination to confirm the presence of pathogenic bacteria.
Examine
Examination of pulmonary capsular histoplasmosis
1. Pathogen examination: sputum, fiberoptic bronchoscopy, lavage fungus culture for more than 4 weeks, mycelium phase to yeast phase, visible characteristic gear-like spores.
Pathological examination aims to find pathogens, which can be stained with silver, PAS staining, etc. If the yeast with a capsule is found in macrophages or leukocytes, the immunohistochemistry can accurately identify the strain and spread. Types of cases of bone marrow, lymph nodes, secretions and biopsy tissue culture are often positive.
2. Histoplasmin skin test: The significance and method are similar to those of PPD (tuberculin pure protein derivative) skin test. The results of 48~72h after skin test are positive for redness and induration 5mm. Have been or are being infected by histoplasmosis, and have certain diagnostic value for patients in non-endemic areas. Generally, skin test is positive after 2 to 3 weeks after infection, and can be maintained for several years. Negative skin test can not rule out diagnosis, so it is mainly used for epidemic. Disease investigation.
3. Serological test: The existing serological antibody detection is not high, and the immunosuppressive person can be false positive, which can only prompt diagnosis.
The complement fixation test (CFT) is the main basis for clinical diagnosis. It is generally believed that a titer of 1:16 or a recent increase of more than 4 times indicates an active disease, an immunodiffusion test (ID), and a specificity higher than CFT. "H" or "M" sedimentation zone is positive, the former often prompts active infection.
Enzyme-linked immunosorbent assay (ELISA) is positive for titer 1:16. In recent years, the detection of histoplasma glycogen antigen (HAP) positively reveals active infection, which can provide early diagnosis basis for immunodeficiency patients. More diagnostic value.
X-ray showed nodular infiltration, single or multiple thin-walled cavities, surrounded by inflammatory infiltration, lesions mainly in the upper lobe, fibrosis, upper lobe contraction, and often difficult to identify with tuberculosis.
Diagnosis
Diagnosis and identification of pulmonary capsular histoplasmosis
The disease should be differentiated from tuberculosis, sarcoidosis, bacterial pneumonia, viral pneumonia, and lung cancer.
