Transmitted Off Crossed Circular Polarized Light Illumination
Alternaria fungal spores (conidia) are characterized by their "tail" and the regular divisions across their length (muriform
septation, see references). There are many different species of the Alternaria fungus. They are very common in Temperate
and Tropical climates. They do not grow in transformer oil.
The Dermestid beetle larva setae is characterized by its unique barbed structure. It is also known as the common Carpet Beetle. This may
be a contaminant from a sample bottle.
Significance in the Environment:
The ubiquitous nature of spores can be seen in the presence of this Alternaria spore found in an oil
sample collected from a transformer. In this case the Alternaria spore simply indicates exposure to
Alternaria may grow in homes and can be a potent allergen but their presence in an indoor tapelift or air sample does not
generally indicate that they are the source of any health complaints unless the population is very high. Chains of
Alternaria spores are typically found in tapelifts if Alternaria is growing in the building. Having more Alternaria spores
in indoor air samples than are seen outdoors is not necessarily an indication that Alternaria is growing in the
building unless it is orders of magnetude higher. The residence time for spores, pollens and other
exterior dusts are long and a higher count of Alternaria spores in the building may simply reflect
a higher outdoor level days, weeks, or months earlier. As with all fungae, if they are growing in a building then that
indicates a moisture control problem. Control the moisture and the fungae will be controlled. Control the moisture first,
then remediate the fungus.
Dermestid beetles are common in indoor environments. They are rather small at less than three millimeters. The larva is covered with setae
of two types. This is the common body type. The other setae has more straight barbs and they form a bush at the tail of the larva.
de Hoog, G. S and J. Guarro, ATLAS OF CLINICAL FUNGI, ISBN 90-70351-26-9, 2nd Ed., 1996