Histoplasmosis

Answer 1

Definition

Histoplasmosis is an infection due to the Histoplasma capsulatum fungus.

Alternative Names

Ohio River Valley fever

Causes, incidence, and risk factors

Histoplasmosis is a fungal infection. It occurs throughout the world. In the United States, it is most common in the southeastern, mid-Atlantic, and central states.

The infection enters the body through the lungs. Histoplasma fungus grows as a mold in the soil, and infection results from breathing in airborne particles. Soil contaminated with bird or bat droppings may have a higher concentration of histoplasma.

There may be a short period of active infection, or it can become chronic and spread throughout the body.

Histoplasmosis may have no symptoms. Most people who do develop symptoms will have a flu-like syndrome and lung (pulmonary) complaints related to pneumonia or other lung involvement. Those with chronic lung disease (such as emphysema and bronchiectasis) are at higher risk of a more severe infection.

About 10% of people with histoplasmosis will develop inflammation (irritation and swelling) in response to the initial infection. This can affect the skin, bones or joints, or the lining of the heart (pericardium). These symptoms are not due to fungal infection of those body parts, but to the inflammation.

In a small number of patients, histoplasmosis may become widespread (disseminated), and involve the blood, meninges (outer covering of the brain), adrenal glands, and other organs. Very young or very old people, or those who have a weakened immune system (due to AIDS, cancer, or transplant, for example) are at higher risk for disseminated histoplasmosis.

Symptoms

Symptoms depend on the type of infection:

• Acute asymptomatic pulmonary (lung) histoplasmosis -- no symptoms
• Acute symptomatic pulmonary histoplasmosis:
  • Fever
  • Chills
  • Cough
  • Chest pain when breathing in
• Chronic pulmonary histoplasmosis:
  • Chest pain
  • Cough
  • Excessive sweating
  • Fever - may resemble symptoms of pulmonary tuberculosis and include coughing up blood (hemoptysis)
  • Shortness of breath
• Disseminated histoplasmosis:
  • Fevers
  • Headache
  • Neck stiffness
  • Mouth sores
  • Skin lesions
• Other histoplasma symptoms:
  • Joint pain
  • Rashes
  • Skin nodules(red lumps called erythema nodosum)

Signs and tests

How histoplasmosis is diagnosed depends on the body parts involved. Tests may look at the sputum, lung tissue, blood, cerebrospinal fluid (CSF), or bone marrow for signs of the fungus. An antigen test may be done on blood, urine, or CSF.

In addition, x-rays may show abnormalities in the lungs or lymph nodes of the chest. These are signs of histoplasmosis.

Treatment

The main treatment for histoplasmosis is antifungal drugs. In the case of pulmonary histoplasmosis, this may include oral (taken by mouth) medicines such as itraconazole or ketoconazole.

Sometimes, especially in immunosuppressed people, long-term treatment with anti-fungal drugs are used after treatment with amphotericin.

Expectations (prognosis)

What happens depends on the extent of the infection and the overall health of the individual. The Death Rate is fairly high for people with untreated widespread (disseminated) histoplasmosis, but is reduced significantly with treatment.

Complications

• Fibrosing mediastinitis -- scarring in the chest that may entrap the following body parts:
  • Great vessels (the major blood vessels carrying blood to and from the heart)
  • Esophagus (food pipe)
  • Heart
  • Lymph nodes
• Inflammatory syndromes involving:
  • Heart lining (pericarditis)
  • Joints (Arthritis)
  • Rashes (erythema nodosum, erythema multiforme)
  • Skin nodules
• Mediastinal granuloma -- enlarged chest-cavity lymph nodes, which may compress body parts such as the esophagus and blood vessels of the lungs
• Medication side effects (for example, amphotericin can have severe side effects)

In addition, people who have a weakened immune system may develop disseminated disease, which can infect the meninges of the brain (causing meningitis).

Calling your health care provider

Notify your health care provider if you live in an area where histoplasmosis is common, and you develop flu-like symptoms, chest pain, cough and shortness of breath. While there are many other illnesses that have similar symptoms, you may need to be tested for the possibility of histoplasmosis.

Prevention

Minimize exposure to dust in contaminated environments such as chicken coops and bat caves. Wear protective equipment such as masks if you work in these environments.

ReferencesKauffman CA. Histoplasmosis. In: Goldman L, Ausiello D, eds.Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 353.

Answer 2

Definition

Histoplasmosis is an infection that occurs from breathing in the spores of the fungus Histoplasma capsulatum.

Alternative Names

Ohio River Valley fever; Fibrosing mediastinitis

Causes, incidence, and risk factors

Histoplasmosis is a fungal infection. It occurs throughout the world. In the United States, it is most common in the southeastern, mid-Atlantic, and central states.

Histoplasma fungus grows as a mold in the soil. You can get sick when you breathe in spores produced by the fungus. Soil that contains bird or bat droppings may have larger amounts of this fungus. The threat is greatest after an old building is torn down or in caves.

Having a weakened immune system increases your risk for getting or reactivating this disease. Very young or very old people, or those with AIDS, cancer, or an organ transplant have more severe symptoms.

People with chronic lung disease (such as emphysema and bronchiectasis) are at higher risk of a more severe infection.

Symptoms

Most people have no symptoms, or only have a mild flu-like illness.

If symptoms do occur, they may include:

• Fever and chills
• Cough and chest pain when breathing in
• Joint pain
• Mouth sores
• Red skin bumps called erythema nodosum, most often on the lower legs

The infection may be active for a short period of time, and then the symptoms go away. Sometimes, the lung infection may become long-term (chronic). Symptoms include:

• Chest pain and shortness of breath
• Cough, possibly coughing up blood
• Fever and sweating

In a small number of patients, histoplasmosis may spread throughout the body. These symptoms are not due to the infection, but instead are due to irritation and swelling (inflammation) in response to the infection. Symptoms may include:

• Chest pain from swelling in the lining around the heart
• Headache and neck stiffness from swelling in the covering of the brain and spinal cord
• High fever

Signs and tests

Histoplasmosis is diagnosed by:

• Biopsy of the lung, skin, liver, or bone marrow
• Blood or urine tests to detect histoplasmosis proteins or antibodies
• Cultures of the blood, urine, or sputum (this test provides the clearest diagnosis of histoplasmosis, but results can take 6 weeks)

To help diagnose this condition, your doctor may perform:

• Bronchoscopy
• Chest CT scan
• Chest x-ray
• Spinal tap to look for signs of infection in cerbrospinal fluid (CSF)

Treatment

Most of the time, histoplasmosis clears up without treatment. Resting and taking medication can control a fever.

If you are sick for more than 1 month or are having trouble breathing, your doctor may prescribe medication. The main treatment for histoplasmosis is antifungal drugs. Amphotericin B, itraconazole, and ketoconazole are the usual treatments.

• Antifungals may need to be given through a vein, depending on the form or stage of disease.
• Some of these medicines can have side effects.

Sometimes, long-term treatment with antifungal drugs may be needed. You may need to take these medications for up to 1 to 2 years.

Expectations (prognosis)

The outlook depends on how severe the infection is, and the patient's health. Some people get better without treatment. An active infection will usually go away with antifungal medicine, but there may be scarring left inside the lung.

The death rate is higher for people with untreated widespread (disseminated) histoplasmosis whose immune system is not working well.

Complications

Scarring in the chest cavity may trap:

• The major blood vessels carrying blood to and from the heart
• The heart itself
• The esophagus (food pipe)
• The lymph nodes

Enlarged lymph nodes in the chest (called mediastinal granulomas) may press on body parts such as the esophagus and blood vessels of the lungs.

Calling your health care provider

Call your health care provider if you live in an area where histoplasmosis is common, and you develop flu-like symptoms, chest pain, cough, and shortness of breath. While there are many other illnesses that have similar symptoms, you may need to be tested for histoplasmosis.

Prevention

Histoplasmosis may be prevented by reducing exposure to dust in chicken coops, bat caves, and other high-risk locations. Wear masks and other protective equipment if you work in these environments.

ReferencesKauffman CA. Histoplasmosis. In: Goldman L, Ausiello D, eds.Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011: chap 340. Reviewed By

Review Date: 12/29/2011

Jatin M. Vyas, MD, PhD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.