By Benjamin J. Pitts
Overview
Vittaforma corneae is a human-infecting
microsporidia species. V. corneae can
cause eye infections in immunocompetent individuals, and has also been linked
to causing infections in immunocompromised AIDS patients. V. corneae is a member of the microsporidia family. Microsporidia
are extremely widespread and they infect nearly every organism on earth from
honey-bees and silkworm to mammals and birds. Relatively little is known about
the epidemiology of microsporidia, as transmission and infection pathways are
still somewhat unclear. Though active spores have been found in water sources
in developed and developing nations, microsporidiosis remains primarily a
disease of HIV and AIDS patients. Despite the relatively recent discovery of
this pathogen, the infection among AIDS patients is remarkable and the parasite
will be of growing importance in the future as HIV continues to spread and more
research is undertaken to understand the role microsporidia play in the human
health. Microsporidia are described as intracellular parasites that infect a
wide variety of vertebrate and invertebrate hosts.
Life Cycle
Microsporidia are characterized by the production of resistant spores
that vary in size. The infective form of microsporidia is the resistant spore
and it can survive for extended periods of time in the environment. The spore
pokes out its polar tubule and infects the host cell. The spore is injected
into the sporoplasm into the eukaryotic host cell through the polar tubule.
Inside the cell, the sporoplasm undergoes extensive multiplication either by
binary fission or multiple fissions. This development can occur either in
direct contact with the host cell cytoplasm or inside a vacuole termed
parasitophorous vacuole. Either free in the cytoplasm or inside a
parasitophorous vacuole, microsporidia develop by sporogony to mature spores.
During sporogony, a thick wall is formed around the spore, which provides
resistance to adverse environmental conditions. When the spores increase in
number and completely fill the host cell cytoplasm, the cell membrane is
disrupted and releases the spores to the surroundings. These free mature spores
can infect new cells thus continuing the cycle.
Diagnosis
The
methods of diagnosis typically involve identifying spores in feces, urine,
other bodily fluids or body tissues. Transmission electron microscopy is the top notch way for identifying specific
species and diagnosing microsporidiosis but is often too expensive and time
consuming. Another way to view V. corneae
is with light microscopy using various stains including gram stains, which the V. corneae are gram-positive. V. corneae is said to cause urinary
tract infections as well as ocular infections. One of the prominent conditions
related to V. corneae is keratitis.
Keratitis is a condition in which the eye's cornea, the front part of the eye,
becomes inflamed. The condition is often marked by moderate to intense pain and
usually involves impaired eyesight.
Treatment
One treatment is with albendazole and is the
most common for all species and is coupled with topical Fumagillin for ocular
infections. However, most drug treatments will not fully eradicate the
parasites. New, more effective drugs for microsporidiosis are still being
discovered and tested.
Conclusion
The
widespread location of microsporidia is a reason concern. With not much being
known about the species and its devastating affects on the immunocompetent. The
world should switch its funding to help combat these dangerous parasites that
cause one to lose their eyesight.
Above is a map of the places that Microsporidia have been
reported.
References
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