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Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. Its symptoms vary greatly, but the disease primarily affects the lungs. When other organs are affected, it is called disseminated histoplasmosis, which can be fatal if untreated.
Positive histoplasmin skin tests occur in as many as 80% of the people living in areas where H. capsulatum is common, such as the eastern and central U.S. Infants, young children, and older persons (in particular those with chronic lung disease) are at increased risk for severe disease. Disseminated disease is more frequently seen in people with cancer or AIDS.
Causes & Development; Risk Factors
The H. capsulatum fungus grows in soil and material contaminated with bat or bird droppings, and is especially prevalent in the American mid-west, the Caribbean, and Central and South America. Spores become airborne when contaminated soil is disturbed, and breathing the spores causes infection. The disease is not infectious.
After the spores have been inhaled into the body, they develop into their pathogenic yeast form. They can reproduce and spread through the blood, usually accumulating in the lungs. A person with a strong immune system will develop a nearly complete lifelong immunity within two weeks of exposure. The main factors that determine the course of the infection are the immune system of the infected person and the extent of exposure. For this reason, people who are HIV positive are particularly at risk of a severe case of histoplasmosis if infected.
Past infection results in partial protection against ill effects if reinfected.
Signs & Symptoms
Most of those affected have no apparent ill effects, but if symptoms occur, they will start within 3 to 17 days of exposure; the average is 10 days. The acute respiratory disease is characterized by respiratory symptoms, a general ill feeling, fever, chest pains, and a dry or nonproductive cough. Distinct patterns may be seen on a chest X-ray. Chronic lung disease resembles tuberculosis and can worsen over months or years. The disseminated form is fatal unless treated.
Disseminated histoplasmosis usually affects an immunosuppressed person and spreads outside the lungs to other body parts. When histoplasmosis spreads, it can affect bone marrow, the liver, spleen, lymph nodes, mouth, intestines, brain, and the adrenal glands. Disseminated histoplasmosis can be fatal, but is extremely rare. Symptoms of disseminated histoplasmosis include:- high fever
- weight loss
- respiratory problems
- myelosuppression (such as anemia)
- hemosepsis
- gastrointestinal bleeding from focal, oral, or mucosal ulcers
- central nervous system disfunction; typically an infection in the form of meningitis
- granulomas; masses that appear in the lymph nodes.
In addition, long-term smokers who have emphysema are more likely to acquire histoplasmosis than others, and often develop a chronic lung complication if infected. When persons with emphysema inhale the fungal spore, they develop "chronic pulmonary histoplasmosis". Symptoms of chronic pulmonary histoplasmosis include:- a severe cough that can produce green or yellow phlegm
- chest pain
- weight loss
- night sweats
- fatigue
- loss of lung parenchyma
In most cases, symptoms last for several months and, if left untreated, can result in either permanently damaged lungs or even death.
There are instances when "acute self-limited histoplasmosis" can be more serious. An infected person might experience muscle pain, joint pain, or irritating red lumps on the arms or legs. If the person has had heavy exposure to the fungal spore, they may also develop bronchopneumonia or enlargement of the lymph glands within the lungs. Also, some people develop an inflammation of the heart lining, a condition that is called "pericarditis". If a person experiences either pericarditis or joint pain, there are medications that can be prescribed to reduce inflammation.
Treatment & Prevention
Antifungal medications are used to treat severe cases of acute histoplasmosis and all cases of chronic and disseminated disease.
When people have disseminated histoplasmosis, or have a mild infection but either have an underlying disease or are immunosuppressed, medication is necessary. Typically, in cases that are not too severe, a doctor will prescribe Itraconozole, taken orally. The length of time a person must take Itraconozole varies according to the severity of the infection. It is usually effective and tolerable, although it can have negative side-effects when taken with other types of medication.
In cases that are more severe, a doctor might prescribe Amphotericin B, generally for 4-12 weeks. In 90% of cases where Amphotericin B is used, the histoplasmosis infection is destroyed. It is administered intravenously, something that many consider a drawback. Many patients with immunosuppressed conditions, particularly people who are HIV-positive, must continue taking Amphotericin B for life in order to prevent a recurrence. Itraconozole can also be used to prevent relapse.
Prognosis; Complications
Mild disease usually resolves without treatment.
While histoplasmosis is generally a mild infection that goes away on its own (the "self-limiting" form of the disease), it can progress into a dangerous and even fatal complication, particularly in individuals who have impaired immune systems. Histoplasmosis can spread from the lungs to other body parts in cases where the infected person has AIDS, has leukemia, has recently had an organ transplantation, or has been using corticosteroids. It can be particularly severe with HIV-infected persons. In all of these cases, histoplasmosis can develop into a fatal condition unless treated.
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Conditions that suggest Histoplasmosis: | | | | | Skin-Hair-Nails |  Night Sweats | Various fungal infections are associated with chronic night sweats. Histoplasmosis, an infection usually seen in the southeastern, mid-Atlantic and central United States, is one such illness. You are less likely to have histoplasmosis or another fungal infection if you have had night sweats for more than a few months with no other symptoms. |
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Histoplasmosis can lead to: | | | | | Skin-Hair-Nails |  Night Sweats| | Various fungal infections are associated with chronic night sweats. Histoplasmosis, an infection usually seen in the southeastern, mid-Atlantic and central United States, is one such illness. You are less likely to have histoplasmosis or another fungal infection if you have had night sweats for more than a few months with no other symptoms. |
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KEY | | Weak or unproven link | | | Strong or generally accepted link |
GLOSSARY
Acute
An illness or symptom of sudden onset, which generally has a short duration.
Adrenal (Adrenal Gland, Adrenal Glands, Adrenals)
The adrenal glands sit on top of each kidney and consist of an outer cortex and an inner medulla. Of the 50 or so hormones the adrenals make, only cortisone and adrenaline are recognized by most people. Some of these hormones must be produced to preserve life, while others help resist stress. Other hormones from the adrenals control normal energy output (along with the thyroid) and govern the breakdown of stored energy into quick energy sources. The medulla produces epinephrine and norepinephrine, which are specifically designed to help the body deal with stressful situations. The adrenals control the body's potassium/sodium balance, which is vital for energy production. They also produce sex hormones in minute amounts, which is important for later years when the gonads drop or cease their production.
AIDS
Acquired Immune Deficiency Syndrome. An immune system deficiency disorder that suddenly alters the body's ability to defend itself. The AIDS virus invades the T4 helper/inducer lymphocytes and multiplies, causing a breakdown in the body's immune system, eventually leading to overwhelming infection and/or cancer, with ultimate death.
Anemia (Anaemia, Anemias)
A condition resulting from an unusually low number of red blood cells or too little hemoglobin in the red blood cells. The most common type is iron-deficiency anemia in which the red blood cells are reduced in size and number, and hemoglobin levels are low. Clinical symptoms include shortness of breath, lethargy and heart palpitations.
Antifungal (Antifungals)
An agent that kills or inhibits fungi, or a compound that inhibits either a dermatomycosis like ringworm or athlete's foot, or
one that inhibits Candida albicans either externally as a douche or internally as a systemic antifungal. Examples: Nystatin, griseofulvin, Tabebuia.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.
Central Nervous System (CNS)
A collective term for the brain, spinal cord, their nerves, and the sensory end organs. More broadly, this can even include the
neurotransmitting hormones instigated by the CNS that control the chemical nervous system, the endocrine glands.
Chronic (Chronicity)
Usually referring to chronic illness: Illness extending over a long period of time.
Corticosteroid (Corticosteroids)
Steroid hormone produced by the adrenal cortex.
Gastrointestinal (GI, GI Tract)
Pertaining to the stomach, small and large intestines, colon, rectum, liver, pancreas, and gallbladder.
Human Immunodeficiency Virus (HIV)
A retrovirus associated with onset of advanced immunodeficiency syndrome (AIDS).
Immune System (Immune Response, Immunity)
A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation. The process may involve acquired immunity (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing).
Leukemia
Cancer of the lymph glands and bone marrow resulting in overproduction of white blood cells (related to Hodgkin's disease).
Liver (Hepatic)
The largest and one of the most complex organs of the body, the liver is responsible for much of the metabolism of fats, proteins and carbohydrates. It is the site of much of the body's detoxification. It is connected very closely with digestion and the regulation of blood sugar, among many other functions. Found behind the ribs on the right side of the abdomen, it has many important functions such as removing harmful material from the blood, making enzymes and bile that help digest food, and converting food into substances needed for life and growth. Hepatic: Pertaining to the liver.
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Lymph Nodes (Axillary Nodes, Inguinal Nodes, Lymph Gland, Lymph Glands, Lymph Node, Lymphatic)
Small, bean-shaped nodes at various points throughout the body that function to filter the lymph fluid and attempt to destroy the microorganisms and abnormal cells which collect there. The most common locations are the neck (both sides and front), armpit (axillary) and groin (inguinal), but also under the jaw and behind the ears. Swollen or painful lymph nodes generally result from localized or systemic infection, abscess formation, or malignancy. Other causes of enlarged lymph nodes are extremely rare. Physical examination for lymph nodes includes pressing on them to check for size, texture, warmth, tenderness and mobility. Most lymph nodes can not be felt until they become swollen, and then will only be tender when pressed or massaged. A lymph node that is painful even without touching indicates greater swelling. Lymph nodes can usually be distinguished from other growths because they generally feel small, smooth, round or oval-shaped and somewhat mobile when attempts are made to push them sideways. Because less fat covers the lymph nodes in children, they are easier to feel, even when they are not busy filtering germs or making antibodies. Childrens' nodes enlarge faster, get bigger in response to an infection and stay swollen longer than an adult's. Also known (incorrectly) as lymph glands.
Phlegm
Mucus in the throat or bronchi.
Spleen (Splenectomy)
The largest organ of the lymphatic system in the body, located between the stomach and the diaphragm (the muscle below the lungs which provides the motion for breathing). It destroys old red blood cells, produces lymphocytes and plasma cells, and stores blood. It also has other as yet unknown functions. A splenectomy is the surgical removal of the spleen.
Tuberculosis
Also known as TB, Consumption or "The White Plague", tuberculosis is an infectious disease caused by a bacterium called Mycobacterium tuberculosis, usually affecting the lungs but possibly also the brain, kidneys and bones. Patients may at first be symptom-free or experience a flu-like illness. In the secondary stage, there might be a slight fever, night sweats, weight loss, fatigue and various other symptoms, depending on the part of the body affected. Tuberculosis of the lung is usually associated with a dry cough that eventually leads to a productive cough with blood-stained sputum. There might also be chest pain and shortness of breath.
Ulcer (Ulceration, Ulcers)
Lesion on the skin or mucous membrane.
X-rays (X-ray)
High-energy radiation used to take pictures of areas inside the body.
Yeast
A single-cell organism that may cause infection in the mouth, vagina, gastrointestinal tract, and any or all bodily parts. Common yeast infections include candidiasis and thrush.
Last updated: Nov 08, 2009
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