Histoplasmosis
The content of the article:
- Causes and risk factors
- Forms of the disease
- Disease stages
-
Symptoms
- Pulmonary histoplasmosis
- Cutaneous histoplasmosis
- Disseminated histoplasmosis
- African histoplasmosis
- Features of the course of histoplasmosis in children
- Diagnostics
- Treatment
- Possible complications and consequences
- Forecast
- Prevention
Histoplasmosis is an infectious natural focal disease caused by the fungus Histoplasma capsulatum. The microorganism was first discovered by Samuel Darling at the beginning of the 20th century, which is why the disease is known as Darling's disease. Other names: reticuloendotheliosis, cavers' disease, reticuloendothelial cytomycosis, Ohio Valley disease.
Histoplasma capsulatum fungus in a blood test
Histoplasmosis is widespread in tropical countries, East and South Africa, in the United States (in the Ohio Valley and south of the Mississippi), but the pathogen is found everywhere. Mostly people in rural areas, miners, poultry workers and speleologists are ill.
Most often, histoplasmosis affects the lungs, which is why it was confused with tuberculosis for a long time - both diseases have a similar course.
Causes and risk factors
Histoplasmosis is a consequence of the vital activity in the human body of the causative agent of the infection - the fungus Histoplasma capsulatum, which lives in the decomposed droppings of bats and birds. When it enters the soil, the fungus actively grows, forming a brown mycelium. The spores of the fungus enter the human body. The disease is not transmitted from person to person.
Habitats of histoplasm:
- hollows of old trees;
- caves where birds live;
- poultry houses and poultry farms;
- dirty soil;
- old wells and abandoned buildings.
Histoplasmosis predominantly affects the lungs, so it is often confused with tuberculosis
In the natural environment, the fungus grows in the form of a mycelium, and in the body, at temperatures close to 37 ° C, it turns into parasitic yeast cells that destroy tissues with the formation of nodular foci of necrosis. By airborne dust, the pathogen enters the mucous membranes of the respiratory tract or damaged skin. Spores settle, as a rule, in the lungs, and from there they can spread throughout the body with the blood stream, forming foci in the lymph nodes, liver and other organs (with disseminated form of the disease).
The development of the disease is facilitated by immunodeficiency states.
Forms of the disease
Along the course, histoplasmosis is:
- Acute - a sudden onset with an increase in body temperature, the appearance of flu-like and intoxication syndromes.
- Chronic - a sluggish course with periodic exacerbations, involvement in the pathological process of the skin and mucous membranes. More common than acute.
Depending on the localization, the following forms of histoplasmosis are distinguished:
- pulmonary (mild, moderate, severe);
- cutaneous;
- disseminated;
- African.
Disease stages
Histoplasmosis has four stages of development:
- Incubation period. It lasts from the moment of penetration of the pathogen until the first nonspecific signs of the disease appear (1-2 weeks, up to a month).
- Prodromal period. The pathogen is activated in the body, which is manifested by nonspecific symptoms - loss of strength, weakness, rapid fatigue, headaches. Duration - several days.
- The height of the disease. The appearance and growth of specific signs of histoplasmosis, which depend on the form of the disease. Lasts from 2 weeks to a year.
- Reconvalescence or remission. The duration is individual.
The chronic form of the disease proceeds with alternating periods of exacerbation and remission. During remission, the pathological processes subside, with exacerbation they appear again.
Symptoms
In 80% of people, histoplasmosis is asymptomatic. In this situation, the disease is detected by chance, during preventive examinations or during diagnostics for another reason. In other situations, the symptoms depend on the form and stage of the disease.
Nonspecific signs of histoplasmosis, characteristic of the prodromal stage, and also often accompanying the cutaneous form of the disease:
- increased body temperature (usually to subfebrile values), chills;
- excessive sweating;
- chest pain, cough;
- dyspnea;
- weakness, apathy;
- nausea, vomiting, diarrhea;
- muscle and headaches.
Pulmonary histoplasmosis
Such histoplasmosis is of the following forms:
- Light - the temperature is normal or rises for 3-4 days, the state of health almost does not suffer, the ability to work remains. On the roentgenogram - strengthening of the pulmonary pattern and compaction of the roots of the lungs.
- Moderately severe - fever for 2 weeks, deterioration in general health, weakness, cough, chills, nausea, muscle and bone pain.
- Severe - sudden onset and rapid onset of symptoms, high fever (up to 40-41 ° C) with significant fluctuations during the day (can last up to 6 weeks), tremendous chills, followed by pouring sweat, intense headache and muscle pain, severe weakness, cough, sometimes vomiting, diarrhea, abdominal pain.
- Severe pulmonary. The person is worried about fever, sweating, weakness, chest pain. Radiographs show severe lung tissue defects.
The main manifestation of pulmonary histoplasmosis is fever
Cutaneous histoplasmosis
It is characterized by the appearance on the skin of rashes, red papules, nodes, follicles, plaques. A typical sign of cutaneous histoplasmosis is nodular or exudative erythema multiforme. The skin becomes red, irritated and hot to the touch. Skin defects can be keratinized or necrotic.
Skin rash is a symptom of cutaneous histoplasmosis.
Often, the cutaneous form of histoplasmosis is accompanied by symptoms of general intoxication (asthenia, decreased appetite, nausea, headache).
Disseminated histoplasmosis
The most severe form, which is characterized by damage to both the lungs and other internal organs, skin, mucous membranes. Exists:
- Acute disseminated histoplasmosis - high fever, chills with subsequent torrential sweating, hacking cough with hemoptysis, severe general intoxication. Multiple foci appear on the skin and mucous membranes in the form of maculopapular or hemorrhagic rash, boils, erythema multiforme or nodosum. Lymph nodes, liver, spleen enlarge, signs of meningoencephalitis, endocarditis, peritonitis, colitis often join. This form of the disease is common in patients with AIDS.
- Chronic disseminated histoplasmosis - at first a sluggish course, unexpressed symptoms, involvement in the process mainly of the skin and mucous membranes (ulcers are observed in the tongue, pharynx and larynx). Gradually, the general condition worsens, a septic-type fever appears, the liver, spleen, and lymph nodes increase. Often, the eyes (chorioretinitis) and the stomach are involved in the pathological process.
African histoplasmosis
Unlike the classic (sometimes called American), this histoplasmosis rarely forms a pulmonary form; mainly the skin and mucous membranes are affected (in severe cases, internal organs). The so-called cold abscesses (painless swelling on the skin), fistulas and fistulas, nodular rashes like molluscum contagiosum or viral warts appear. There may be an increase in lymph nodes with their subsequent suppuration, damage to the bones of the arms, legs and skull in the form of purulent fistulas.
Features of the course of histoplasmosis in children
In children 2–6 months of age, histoplasmosis occurs in a disseminated form. Fever, foul-smelling foamy stools, significant enlargement of the liver, spleen and lymph nodes are characteristic. The lungs are always drawn into the pathological process (in contrast to adults, who can develop an isolated skin form of the disease).
In children of the first six months of life, with histoplasmosis, the lungs are almost always affected
In the blood - anemia, leukopenia, poikilocytosis, anisocytosis, thrombocytopenia, increased levels of bilirubin and transaminases. Histoplasmas or antibodies to them are isolated from the blood of a sick child.
Diagnostics
The diagnosis is confirmed by the isolation of the pathogen from the blood, sputum, scrapings from the oral mucosa, lymph nodes, bone marrow, cerebrospinal fluid, feces, urine. Histoplasm is detected by smear microscopy.
Antibodies to Histoplasma capsulatum are detected using serodiagnostics: precipitation, agglutination, complement binding reactions. However, these studies are not informative for pathologies of the immune system.
An intradermal test with histoplasmin is performed: 0.1 ml of the allergen, diluted in a ratio of 1: 1000, is injected into the skin. The result is checked after 24 and 48 hours. This study is informative from the 2nd to 4th week of illness.
To diagnose histoplasmosis, an intradermal test with histoplasmin is indicated.
Additional diagnostic methods:
- general analysis of blood and urine;
- blood chemistry;
- chest x-ray.
In HIV-infected patients, the diagnosis of histoplasmosis is difficult due to negative serological reactions and an intradermal test with histoplasmin. An HIV test is recommended for all individuals with histoplasmosis.
Treatment
In asymptomatic, mild and moderate forms of histoplasmosis, specific antifungal therapy is not performed; symptomatic treatment and restorative measures are prescribed (gentle regimen, good rest, vitamin therapy, balanced nutrition).
Severe forms of histoplasmosis require the use of systemic antifungal drugs. Additionally, according to indications, hyposensitizing agents, hepatoprotectors, immunomodulators, corticosteroids, etc. are prescribed.
Possible complications and consequences
In most cases, histoplasmosis is easy and leaves no unwanted consequences. However, young children and people with weakened immunity can develop serious complications, up to and including death:
- obstruction of the bronchi;
- superior vena cava syndrome;
- fibrosing mediastinitis;
- meningitis and encephalopathy;
- uveitis;
- reactive arthritis;
- heart failure;
- liver failure;
- adrenal insufficiency.
Forecast
The outlook is generally favorable. In people with immunodeficiency, as well as in severe acute and chronic forms of the disease, it worsens.
Prevention
The specific prevention of histoplasmosis is vaccination, and the vaccine does not prevent infection, but it facilitates the course of the disease and reduces the risk of complications.
Non-specific prevention is aimed at preventing infection. Regular check-ups are recommended for people living in endemic areas and engaged in activities that put them at high risk of contracting Histoplasma capsulatum. Avoid contact with open ground (it is especially dangerous to inhale dust), and thoroughly wash fruits and vegetables, treat superficial skin lesions. Tourists visiting endemic areas are advised to undergo a medical examination after returning home.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
