Histoplasmosis

Introduction to histoplasmosis Histoplasmosis is a highly contagious fungal disease that is often transmitted by the respiratory tract. It first invades the lungs and then through the skin and other mononuclear macrophages such as the liver and spleen. It can also invade the kidneys, central nervous system and other organs. Device. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: respiratory transmission Complications: multiple lung infections scars

Cause of histoplasmosis

(1) Causes of the disease

This genus is a biphasic bacterium, which is yeast-type in the tissue and grows in cells. It is hyphal in culture at room temperature of 28 °C. It is highly infectious and can cause laboratory infection. The disease consists of capsular tissue cytoplasm. Caused by bacteria, through the respiratory tract, skin, mucous membrane and gastrointestinal afferent, patients in the epidemic area and feces such as infected animals can carry bacteria; chicken nest can also hide this bacteria, when the pathogen invades the human body, depending on the patient's resistance Weak and morbidity, manifested as primary or disseminated infection.

(two) pathogenesis

The disease is caused by capsular histoplasma, and it can be carried through the respiratory tract, skin, mucous membrane and gastrointestinal tract. The excretions of patients in the epidemic area and the feces of infected animals can be carried; the chicken nest can also hide this bacteria when people inhale After the spores of the bacteria, the primary lung infection is caused first, and the healthy person often fails to heal, but the immune function is low or the defect, such as malignant disease, or a large amount of corticosteroids and immunosuppressive agents, or inhalation of a large number of spores, A lung lesion is formed that spreads throughout the body through lymph or blood.

Histoplasmosis prevention

The hyphae type of this strain is highly infective, and laboratory workers should pay attention to prevention. In the bird cages, chicken nests, etc., there is often contamination of the bacteria. Prevention should be taken. People who are in the first epidemic area have poor immunity due to the body. Special attention should be paid to preventing infection.

Histoplasmosis complications Complications multiple lung infection scars

Fortunately, serious complications associated with histoplasmosis are rare, including:

1. Forming fibrous tissue in the inner layer of the pulmonary cavity wall, squeezing the esophagus, heart or lungs, affecting their normal function.

2, swollen lymph nodes, squeezed the trachea, large blood vessels in the esophagus or chest.

3. Leaves the lung tissue scarred.

4, secondary pulmonary infection.

5, blindness, if the infection spread to the eye, it may happen.

Symptoms of histoplasmosis Symptoms Common symptoms Calcification, dry cough, night sweats, high fever, phlegm, swollen lymph nodes, low fever, lung infection, splenomegaly, leukopenia

The pathogen of this disease can invade all organs of the body. Therefore, the clinical manifestations are complicated and are mainly divided into the following types:

1. Primary histoplasmosis has different organs and symptoms, and the symptoms are different. Taking lung histoplasmosis as an example, it can be divided into 5 types.

1 acute asymptomatic type: about 95% of primary histoplasmosis can be asymptomatic. In the endemic population, many calcifications can be seen in the lungs, but the patient's medical history is followed, but there are no obvious symptoms.

2 mild infection type: patients only have dry cough, chest pain, shortness of breath, hoarseness and other symptoms of upper respiratory tract infection, children can often be expressed as children's "summer heat" symptoms,

3 moderate infection type: may have fever, night sweats, weight loss, slight hair loss, occasional or hemoptysis, sometimes the pathogens can be cultured from the sputum and bone marrow, X-ray examination shows that there are most scattered infiltrates or nodular lesions in the lung field. The hilar lymphadenopathy is similar to primary pulmonary tuberculosis. When it is severely disseminated, it is like lymphoma or other tumors. The lesions are absorbed slowly, a few can be fibrotic, calcified, and there is a calcification point in the primary calcification area, which is characteristic of the spleen. Calcified foci can be seen inside, and occasionally in the liver, sometimes adult lung histoplasmosis resembles tuberculosis.

4 epidemic type: formerly known as "cave fever", is a kind of pulmonary allergic disease, the histoplasmin skin test is positive, showing acute miliary pneumonia, primary atypical Pneumonia, etc., mainly seen in patients who inhale a large number of spores, the incubation period is about 7 to 14 days, may have high fever, severe chest pain, difficulty breathing, and may also have severe hepatitis performance,

5 Chronic type: This type is common in men. It is difficult to distinguish from chronic cavitary tuberculosis. It is characterized by cough, phlegm, interstitial or hemoptysis, low fever, and gradual weakness. X-ray examination shows the formation of hollow cavities, which are often difficult to absorb. Spread all over the body.

2. Disseminated histoplasmosis disseminated histoplasmosis type 3,

1 benign infection: often caused by primary pulmonary infection, there are many miliary calcifications in the spleen, liver and other mononuclear phagocytic system, and after healing, a calcification similar to tuberculosis is formed.

2 progressive adult infection: manifested as splenomegaly similar to leishmaniasis, can have anemia, leukopenia, lung symptoms are not obvious, sometimes there are large lung consolidation, the patient will die soon,

3 Children with fulminant infections: more common in children under the age of 1 in the endemic areas, only a few can be self-healing or cured, most of them die in the short term.

The diagnosis is mainly based on the yeast type bacteria found in the specimens from the sputum, peripheral blood, bone marrow, lymph node puncture, biopsy, etc., combined with clinical symptoms and culture examination, the tissue cytoplasmin skin test can help diagnose, especially the disease period. For longer patients, a 1:1000 dilution of 0.1m1 is usually used for intradermal injection. After 72h, the local redness is less than 8mm, indicating that the skin test is negative, and the disease can be excluded. In the highly endemic area, if the skin test is positive, it should be combined. Other indicators can determine the diagnosis, serum test is very helpful for diagnosis, and the increase in titer can help to judge the prognosis. The serum test should be carried out before the cytoplasmin skin test to avoid the increase of the titer due to the skin test. , a false positive occurred.

Examination of histoplasmosis

The disease can not be diagnosed by medical history and clinical manifestations. Chest X-ray examination and computed tomography have diagnostic value. Serological test positive is helpful for diagnosis. The mycelial antigen is determined to be 1:4 and yeast type. The antigen is 1:16, which is a strong evidence of disease activity. The positive intradermal test of histoplasmin indicates past or present infection. It is suitable for census. Agar gel biphasic diffusion test is more specific than complement fixation test, but It has cross-reactivity with bud and coccidioidomycosis, so it is necessary to simultaneously test the phytoplasmin, germin and coccidiostat skin for identification.

, urine, blood, bone marrow, pleural effusion and other secretions smear or culture to isolate capsular histoplasma, or pathological tissue sections found yeast-type fungi, can be diagnosed, fiberoptic bronchoscopy biopsy and lavage culture have diagnostic value It is more suitable for uncalcified nodular lesions and cavitary lesions. Superficial lymph node biopsy, liver, spleen, lung and other biopsy are important for diagnosis, but visceral puncture should be cautious.

Progressive adult infection: manifested as a splenomegaly similar to leishmaniasis, with anemia and leukopenia.

Chronic type: X-ray examination shows the formation of hollow cavities, often difficult to absorb.

Diagnosis and identification of histoplasmosis

All stages of the disease should be distinguished from tuberculosis, mainly relying on culture and corresponding serological examination. The acute phase of primary histoplasmosis should be associated with viruses, bacterial and other fungal lung inflammation and diffuse lungs. Differentiation of fibrosis, lipidoid pulmonary lesions, acute disseminated histoplasmosis, splenomegaly, lymphadenopathy, anemia and leukopenia, and visceral leishmaniasis, lymphoma, infection Sexual mononucleosis, Manifeci's blue mold, dysentery, brucellosis, etc., skin and mucous membrane damage, should be associated with tumor, sporotrichosis, syphilis, bacterial cellulitis, skin tuberculosis, toxoplasma Identification of diseases or other systemic fungal infections.

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