See also AGING, EFFECTS ON IMMUNE RESPONSE;
BLISTER; GENITAL HERPES; HERPES SIMPLEX; SPINAL
NERVES.
histoplasmosis An illness resulting from INFEC-
TIONwith the FUNGUSHistoplasma capsulatum. This
fungus, commonly called a mold, thrives in soils
where bird droppings are abundant, such as
chicken farms, barns where pigeons and starlings
nest, and caves where bats roost. Histoplasmosis is
endemic (continuously present) in the river valley
areas of the central United States, where the rich
and acidic soil provides an especially supportive
environment for fungi to grow.
When inhaled, the H. capsulatumspores cause
lesions in the LUNGS. An acute infection causes
symptoms only in about 10 percent of people,
though nonetheless can do considerable damage
to lung tissue. Permanent scarring (granulomas
and cavitations) often occurs in untreated histo-
plasmosis. Chronic histoplasmosis may develop in
people who have underlying pulmonary disease
or repeated exposure to H. capsulatumspores. The
most significant risk of histoplasmosis is dissemi-
nated disease, in which the spores enter the BLOOD
circulation and migrate to other organs through-
out the body. Disseminated histoplasmosis, often
an OPPORTUNISTIC INFECTION in people who have
HIV/AIDSor are otherwise IMMUNOCOMPROMISED, has
a high rate of fatality.
Symptoms and Diagnostic PathSymptoms in acute histoplasmosis generally
appear within two weeks of exposure and include
- FEVER
- HEADACHE
- JOINT PAIN
- MUSCLEaches
- nonproductive (dry) COUGH
People who inhale a large quantity of the
spores may have extensive lung involvement that
causes shortness of breath (DYSPNEA). The diagnos-
tic path begins with a detailed personal health his-
tory with emphasis on exposure to bird droppings,
blood tests, and a SKIN ANTIGENtest. Chest X-RAY
reveals the characteristic histoplasmosis lesions,
and may also show enlarged LY M P Hnodes in the
chest (hilar and mediastinal LYMPHADENOPATHY).Treatment Options and Outlook
Acute histoplasmosis usually resolves without
treatment, running a course much like that of a
common upper respiratory infection. Bacterial
PNEUMONIAmay occur as a complication of acute
histoplasmosis, requiring treatment with ANTIBIOTIC
MEDICATIONS. Doctors prescribe ANTIFUNGAL MEDICA-
TIONSto treat moderate to severe acute symptoms,
chronic histoplasmosis, and disseminated histo-
plasmosis. With appropriate treatment, most peo-
ple who have normal immunocompetence recover
though residual lung damage is possible. Chronic
and disseminated forms of infection often require
long-term or lifelong treatment with antifungal
medications.ANTIFUNGAL MEDICATIONS TO TREAT HISTOPLASMOSIS
amphotericin B itraconazole ketoconazoleRisk Factors and Preventive Measures
People who work with live poultry or in outdoor
areas that have large bird populations have
increased risk for infection with H. capsulatum.
Minimizing disturbance of the soil helps reduce the
release of spores into the air. People who work in
areas where exposure is a risk should wear respira-
tors. Recreational activities in areas where birds or
bats are common may also be a risk for exposure.
See also HANTAVIRUS; LESION.HIV/AIDS An INFECTION with the human
immunodeficiency virus (HIV) that ultimately
results in the illness acquired immunodeficiency
syndrome (AIDS). Though new HIV/AIDS infec-
tions are on the decline in the United States and
other industrialized nations, HIV/AIDS remains
endemic on the African continent.
HIV/AIDS spreads through contact with body
fluids such as occurs with sexual contact (vaginal
intercourse, anal intercourse, and oral sex) or
through shared needles among intravenous DRUG
users. Though previously infection through trans-
fused BLOODor blood products was a key means of
infection, screening for HIV antibodies in donatedHIV/AIDS 333