Histoplasmosis is a fungal infection caused by the organism Histoplasma
capsulatum (H. capsulatum). The infection is usually mild and
asymptomatic, but in approximately 5% of cases it causes a sudden, short-term
(up to 10 days), flu-like respiratory illness. In very rare cases (1% to 5%) it
can produce serious syndromes that progress rapidly and may result in death.
Because of the similarity in symptoms, histoplasmosis is sometimes mistaken for
tuberculosis. Approximately 500,000 people are exposed to H. capsulatum
annually in the United States.
Signs and Symptoms
Most cases of histoplasmosis produce no symptoms or symptoms that are
extremely mild. Signs and symptoms that occur in rare cases include the
Acute, flu-like infection - includes fever,
chills, cough, chest pain, and headache
Chronic lung infection - develops gradually
over weeks to months and produces a progressive, worsening cough, weight loss,
night sweats, and possibly, shortness of breath
When the disease spreads throughout the body and affects many organ systems,
a person may experience fever, chills, weight loss, enlarged liver and spleen,
swollen lymph nodes, ulcers in the mouth, stomach ulcers that may bleed,
infection of heart valves, meningitis (inflammation of the membranes of the
brain and spinal cord), anemia, and elevated calcium
The primary cause of histoplasmosis is exposure to the organism H.
capsulatum, which is found primarily in mild climates worldwide. More people
living in the Ohio and Mississippi river valleys of the United States have been
infected with H. capsulatum than anywhere else in the world. H.
capsulatum grows in moist soil that is rich in nitrogen or in areas
contaminated with bird or bat droppings, such as attics, barns, caves, and city
parks. The spores of H. capsulatum are inhaled into the lungs and
transformed into the yeast form of the fungus. The yeast multiply in lung cells,
but usually do not spread to other parts of the body in individuals with healthy
immune systems. In those with weakened immune systems, the yeast may spread to
the lymph nodes, liver, spleen, bone marrow, adrenal glands, and
The risk factors for histoplasmosis include:
Exposure to soil contaminated with bird and bat droppings
Residence in areas where histoplasmosis is prevalent
Construction-related activities, such as bulldozing or demolition,
that disturb contaminated soil
Conditions that suppress the immune system, including AIDS,
corticosteroid therapy, organ transplantation, and chemotherapy
Spelunking (exploring caves)
Male gender - males are four times more
likely than women to become infected
Very young or very old age
Because most cases of histoplasmosis produce no symptoms, the condition can
be difficult to diagnose. In addition to a physical exam, a physician may
perform the following tests to confirm the diagnosis:
Chest X ray
The best solution to the problem of histoplasmosis is to avoid exposure to
H. capsulatum, the organism that causes the infection. The following
steps may help prevent the infection:
Wear masks or respirators when exposed to areas contaminated by bird
or bat droppings
Spray contaminated areas with 3% formalin (this will kill the
Mild cases of histoplasmosis usually require minimal treatment, such as bed
rest and analgesics (pain medication). More serious cases of histoplasmosis,
with symptoms that include a high fever, respiratory distress, loss of appetite,
and malaise, are treated with
antifungal medications (medications
that inhibit the growth of fungi). While complementary and alternative therapies
have not been widely studied for their use in the treatment of histoplasmosis,
preliminary studies suggest that
garlic may enhance the therapeutic effects of
Medications used to treat histoplasmosis inhibit the growth of fungi in the
body. These medications are often used in severe cases when the infection has
spread to various organs and tissues throughout the body.
Amphotericin B (intravenous)
Surgery and Other Procedures
Surgery is only necessary in rare cases when serious complications associated
with the infection arise. Some surgical procedures include:
Laser photocoagulation - procedure used to
prevent visual impairment when infection spreads to the
Surgical resection - procedure used to remove
heart valves infected with H.
Nutrition and Dietary Supplements
Although N-acetylcysteine (NAC) has yet to be investigated in scientific
studies, some researchers theorize that this supplement may be effective in
treating lung infections such as histoplasmosis. Laboratory studies indicate
that N-acetylecysteine may scavenge free radicals (damaging molecules) in lung
tissue, but its effectiveness in humans has yet to be
Garlic (Allium sativum)
Laboratory studies indicate that extracts of garlic (Allium sativum)
may inhibit the growth of H. capsulatum. Studies also suggest that garlic
may enhance the therapeutic effects of amphotericin B, a medication commonly
used to treat histoplasmosis. These findings suggest that individuals with
weakened immune systems who are required to take high doses of amphotericin B to
treat histoplasmosis may benefit from a shorter treatment period at a lower dose
with garlic supplementation. Further studies are needed however, to conclusively
determine what role, if any, garlic may have in the treatment of
A trained herbalist may also recommend the following antifungal herbs to
Grapefruit seed extract
Warnings and Precautions
The medications used to treat histoplasmosis may interact adversely with the
antihistamine medications terfenadine and astemizole, possibly producing
abnormal heart rhythms.
Individuals with histoplasmosis should also avoid supplementation with
vitamin D and calcium; case reports suggest that they may worsen the condition
and promote the spread of infection throughout the body.
Prognosis and Complications
Fortunately, serious complications associated with histoplasmosis are
extremely rare. These complications may include:
Formation of fibrous tissue in the lining of the chest wall cavity,
which may compress the esophagus, heart, or lungs, affecting their ability to
Enlargement of lymph nodes - may constrict
airway, esophagus, or large blood vessels in the chest region
Scar tissue in the lungs
Blindness - may occur if infection spreads to
Many cases of histoplasmosis are mild and resolve in 10 days without
treatment. Occasionally, however, symptoms may persist for several weeks. In the
most severe cases, particularly when the infection spreads to various organs
throughout the body, long-term therapy with antifungal medications may be
necessary. If left untreated, however, such severe cases generally result in
death. Individuals who contract histoplasmosis in areas where infection is
prevalent may experience a second infection - even
after adequate treatment - but the second infection is
usually milder than the first. Relapse is more likely in those with weakened
immune systems, although it can happen in individuals with healthy immune
systems as well. In general, however, histoplasmosis produces no long-term
complications and is rarely fatal.
Bennett JE. Histoplasmosis. In: Fauci AS, Braunwald E, Isselbacher KJ, et al,
eds. Harrison's Principles of Internal Medicine. 14th ed. New York, NY:
McGraw Hill; 1998:1150-1151.
Blumenthal M, ed. Herbal Medicine: Expanded Commission E Monographs.
Newton, Mass: Integrative Medicine Communications; 2000:33-35.
Bradsher RW. Histoplasmosis and blastomycosis. Clin Infect Dis.
Conces DJ Jr. Histoplasmosis. Semin Roentgenol. 1996;31(1):14-27.
Davies SF. Histoplasmosis: update 1989. Semin Respir Infect.
Davis LE, Shen J, Royer RE. In vitro synergism of concentrated
Alliumsativum extract and amphotericin B against Cryptococcus
neoformans. Planta Med. 1994;60(6):546-549.
Fliermans CB. Inhibition of Histoplasmacapsulatum by garlic.
Mycopathol Mycol Appl. 1973;50(3):227-231.
Kelly GS. Clinical applications of N-acetylcysteine. Altern Med Rev.
Laurent T, Markert M, Feihl F, Schaller MD, Perret C. Oxidant-antioxidant
balance in granulocytes during ARDS. Effect of N-acetylcysteine. Chest.
Mandell GL, et al. Mandell, Douglas, and Bennett's Principles and Practice
of Infectious Diseases. 5th ed. Philadelphia, Pa: Churchill Livingstone;
McMillan TA, Lashkari K. Ocular histoplasmosis. Int Ophthalmol Clin.
Murray JJ, Heim CR. Hypercalcemia in disseminated histoplasmosis. Aggravation
by vitamin D. Am J Med. 1985;78(5):881-884.
Murray PR, et al. Medical Microbiology. 3rd ed. St. Louis, Mo: Mosby;
Rubin SA, Winer-Muram HT. Thoracic histoplasmosis. J Thorac Imaging.
Sataloff RT, Wilborn A, Prestipino A, Hawkshaw M, Heuer RJ, Cohn J.
Histoplasmosis of the larynx. Am J Otolaryngol. 1993;14(3):199-205.
Shulman ST, et al. The Biologic and Clinical Basis of Infectious
Diseases. 5th ed. Philadelphia, Pa: W.B. Saunders Company; 1997:176-179.
Tierney LM Jr, et al. Current Medical Diagnosis and Treatment 2000.
New York, NY: Lange Medical Books/McGraw-Hill; 2000:854-855,1464-1465.
Walsh TJ, Gonzalez C, Lyman CA, Chanock SJ, Pizzo PA. Invasive fungal
infections in children: recent advances in diagnosis and treatment. Adv
Pediatr Infect Dis. 1996;11:187-290.
Wheat J. Histoplasmosis: recognition and treatment. Clin Infect Dis.
Review Date: March 2001
Reviewed By: Participants in the review process include: Shiva Barton, ND, Wellspace,
Cambridge, MA; Jacqueline A. Hart, MD, Department of Internal Medicine,
Newton-Wellesley Hospital, Harvard University and Senior Medical Editor
Integrative Medicine, Boston, MA; Lonnie Lee, MD, Internal Medicine, Silver
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