BlastomycosisIntroduction:Blastomycosis
is a relatively rare disease that is caused by inhalation of spores of the mold
species Blastomyces
dermatitidis. In the US this is found in Ohio in the Mississippi
river valleys, in northern Maryland, southern Pennsylvania, New York(central area),
Texas, Florida, southeastern states, northern Midwest and southern Canada. However,
there are other areas in the world, such as Africa and the Middle East where the
spores are also endemic in the soil. Conditions
for multiplication of this pathogen are particularly good when soil is rich in
excretions from animals and the soil is acidy and moist containing decaying organic
material. Blastomycosis dermatitidis grows at room temperature. When the spores
are inhaled and the immune system is weak, the heat increase from room temperature
to body temperature (37°C or 98.6°F) will trigger conversion to large invasive
yeast bugs.The lungs immediately attempt to isolate them by surrounding the
invading pathogen by mononuclear white blood cells that could in a healthy person
stop the invasion. However, with the weakened immune system there is inflammatory
granulation tissue that forms, the disease process enlarges and eventually fibrotic
changes and lung scar tissue are formed. There can also be superinfection with
bacteria or other fungal infections such as Candida albicans. Eventually there
is an invasion into the circulatory system and disseminated blastomycosis
results where blastomycosis foci are found in other organs such
as kidneys, skin, vertebrae and other bones, prostatic and testicular tissue,
thyroid gland, brain, bone marrow and other tissues. This condition is life threatening
and often leads to death. Signs and symptoms: Usually
blastomycosis (also called"Gilchrist's Disease") starts as a lung disease.
It may not be recognized first and simply present as an infection with chills,
a hacking cough and non specific chest pains. The patient may be very tired and
have intermittent fevers and sweats. As the physician does a workup usually a
chest x-ray is ordered, which will alert the physician that there is something
different from the ordinary pneumonia going on. Instead of an infiltrate
in the periphery of the lung, the infiltrate of blastomycosis fans out from the
center of the lung (called"hilum") into the lung tissue. If the disease
is not recognized and it progresses further, the patient gets symptoms from whatever
organ is involved in the now disseminated blastomycosis. The most common symptoms
are skin lesions that can be more local or often also distributed all over the
body surface, but with preference to exposed areas. They look like pimples, but
can also look wart like. The lesions heal in the center leaving scarred skin behind,
but advancing in the outside. The advancing border has a steep slope and there
are often a number of mini abscesses along this border, which have a purplish
red color. Diagnostic
tests: In the earlier form when only lung tissue is involved X-rays
show characteristic changes suggestive of blastomycosis. However, bronchoscopy
must be done by a respirologist to confirm the diagnosis. Samples can be taken
for microscopic slides and with utilizing special staining techniques the lab
can come up with the specific diagnosis. If this is not conclusive, then a blastomycosis
cultures would confirm the diagnosis, which would also detect more minute
quantities of the pathogen. Other diseases have to be excluded with appropriate
tests such as cancer (bronchogenic carcinoma), other mycoses or tuberculosis.
Treatment: If blastomycosis is untreated, it would
slowly and relentlessly infect the patient until the patient would succumb to
the disease. Mild or moderate disease can be treated very successfully with the
antifungal antibiotic itraconazole (brand name: Sporanox). Fluconazole (brand
name: Diflucan) is less successful. Patients with severe life threatening infections
are treated with intravenous amphotericin B (brand name: Fungizone) (Ref.1, p.1216).
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