| Histoplasma sp is known to
cause histoplasmosis, which is a disease that has a wide
spectrum that range from mild pulmonary infection to chronic
and fatal chronic illnesses. The lungs are especially
infected due to the inhalation of conidia. The reticuloendothelial
system (RES) is largely involved when the infection includes
the Histyoplasma var. capsulatum dissemination. One might
also find cases where Histoplasma capsulatum also gets
involved although this is rare. Thyroid glands may also
be involved by Histoplasma capsulatum although such an
infection is rare as well.
Histoplasma capsulatum var. duboisii does not affect
the lungs but it has a huge bearing on the bones and
the lungs and it is the one responsible for African
histoplasmosis. The nature of this infection makes even
the healthy individuals get affected. The dissemination
however comes to those who are no thoroughly immunized
as well as the elderly. There are has been cases of
chronic cavitary histoplasmosis in those individuals
who have other pulmonary diseases.
Histoplasma capsulatum is a thermally dimorphic and
this makes this fungus to attain a mold from 25 degrees
Celsius and to attain the best form in temperatures
revolving around 37 degrees Celsius. Whenever the fungus
colonies are at 25 degrees, they tend to grow quite
slowly and change from appearing a bit granular to attaining
a cotton stature. The color that is initially white
changes to brown as the fungus advances in age. One
can also observe at the back a yellowish color that
is almost turning to orange.
The features can be made more elaborate when observed
on brain heart infusion sugar (BHIA) or the Sabouraud
dextrose sugar because of their catalytic nature that
allows the fungus to grow more efficiently. Temperatures
at 37 degrees makes allows for the formation of yeast
of yeast cells that are ovoid and narrow-shaped. Var.capsulatum
however creates smaller yeasts as compared to those
of var. duboisii.
The differentiation of Histoplasma capsulatum from
the two genera is best achieved at the conversion of
yeast phase at 37 degrees Celsius, which involves the
hybridization of nucleic acid as well as specialized
exoantigen testing. This also helps in the detection
of antigen, which is also offers, an efficient way histoplasmosis
diagnosis. It is also important to note that Chrysosporium
does not have the ability to produce tuberculate macroconidia
and neither does Sepedonium produce microaleuriconidia
at any point.
Information on Histoplasma sp is still scant and therefore
many of the anti fungal tests have not been widely conducted
to test how this fungus works. There are medications
that can help in inhibiting the fungus although there
is a likelihood of resistance in many instances.
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