those of you who have read my previous article, "Beware the
Ides of Summer", you have no doubt come to the conclusion
that I am keenly interested in the hazards associated with amoeba
that pose the potential for serious infections in human beings.
often we associate amoeba with aquatic environments such as lakes,
ponds, streams, and rivers. Seldom do we give thought to the soil,
the dust which we undoubtedly breath, hot tubs and spas, swimming
pools, tap water or drinking water, dialysis units, heating, venting,
and air conditioner units (HVAC), humidifiers, contact lens paraphernalia,
or even our own nose, throat, and mouth. All of these carry amoeba
and, in some, the amoeba may even host bacteria that can cause
life-threatening illnesses. Following in the steps of one Mynheer
Antonie van Leeuwenhoek, whose letters to the Royal Society in
London some of us have read, I have isolated and observed amoeba
from my own person.
what about this Acanthamoeba spp. which I have referenced
in my title? Acanthamoeba poses a threat similar to that
of the amoeba Naegleria fowleri, the causative agent of
Primary Amebic Meningoencephalitis or PAM, and can be found in
all the referenced environments previously given. But what's the
big deal about these pathogens? We all know that infections are
rare and most always fatal. Well, there is no big deal about them
but they are part of our environment and, as microscopists, something
that we should be aware of. There have been no reported cases
of anyone having self-infected themselves with the amoeba but,
according to "Murphy's Law", there is always that slim
chance one day that someone could, and probably will, infect themselves.
Now that may not be a very professional or scientific statement
but it does hold a significant amount of weight. We handle our
collections of protozoa cultures in a casual way for the most
part, I am assuming, and I too am guilty of the same. However,
it is always in the back of my mind that I am handling a potential
biohazard and should be taking some precautions, however menial
they may be. Although we may harbor these organisms in our bodies,
all it takes is just one of them in the right place at the right
time and you could have a serious and fatal infection up and running.
The dropping or splashing around of water sample collections containing
these and other organism like them pose a threat, however small
and rare that threat may be. From such carelessness, microscopic
droplets or mists can transfer these organisms to the air we breathe.
Our hands are another potential source of infection. By rubbing
ones eyes, eating or drinking, even smoking if you are so inclined
to do so, without washing ones hands after handling or preparing
wet mount slides or even collecting samples, one can possibly
transfer these organisms to one's person.
are many other infections and diseases that are caused by amoeba
and not all of them are fatal but are serious enough, for those
infected with them, to have to acquire medical attention.
so now I am an alarmist, a "Chicken Little", if you
please. Well here are the facts about Acanthamoeba and
they are not pleasing ones.
environments in which these amoebae live and thrive have already
been addressed. Like N. fowleri, they are thermophilic,
capable of living in environments that have extremely warm or,
sometimes, hot temperatures. The result of an Acanthamoeba
infection is the same as that for N. fowleri but the course
of the infection leading to the final end result, death, takes
a much longer route. This route can progress over several weeks.
does one acquire an Acanthamoeba infection? Some of that
has already been addressed, too, but here are some more interesting
facts concerning acquisition. The amoeba can enter the skin through
a cut, wound, or through the nostrils. Having invaded the body,
the amoeba can travel to the lungs and through the bloodstream
to other parts of the body, especially the CNS or Central Nervous
System. Also, through improper handling and disinfection of contact
lenses, one can cause a serious infection of the eye known as
amebic keratitis (AK). Once inside the CNS the symptoms of Granulomatous
Amebic Encephalitis or GAE are pretty much the same as for Primary
Amebic Meningoencephalitis, PAM. They are as follows:
and a stiff neck.
of attention to people and surroundings.
of balance and bodily control.
for treatment, yes skin and eye infections can be treated. As
for the infection of the CNS, Amphotericin B is most commonly
used. Now, have there been any survivors of an Acanthamoeba
infection of the CNS? The answer to that is yes but only five
(5) out of about 300 cases worldwide.
I do not want to make this a long and drawn out report but here
are a few more facts about Acanthamoeba spp. that some may be
interested in. Acanthamoeba are not parasites. They are
free-living amoeba and do not require a host organism to complete
their life cycle, hence the term free-living. There are several
species of Acanthamoeba and they are as follows:
healyi (A. astronyxis)
The main causative agent species of Acanthamoeba are: A.
polyphaga, A. castellanii, and A. culbertsoni.
can be easily isolated and cultured on non-nutrient agar cultures
covered with a dense layer of the bacterium, Escherichia coli.
The trophozoites will feed and replicate on the bacterial food
supply or source. With experience one can identify Acanthamoeba
from other free-living amoeba using microscope slide preparations
and observing the morphology of the amoeba.
hope that you the reader, have found this short article to be
interesting as well as informative and that some of the information
about the hazards handling these organisms will be taken to heart.
With things being the way that they are these days, I must add
a disclaimer to my article: I am not a professional but an
amateur researcher in the field of Protozoology and the study
of pathogenic protozoa. Misuse of the information contained herein
is at the risk of the individual reader or readers and I claim
no responsibility or liability for its misuse and that it is written
for informational purposes only and that my opinions and findings
are that of an amateur and not a professional. For more information
on this and other pathogens of this nature, please contact the
Center for Disease Control, www.cdc.gov or consult your local
offices of health. If you think that you have been exposed or
infected with any of the organisms listed and would like further
information contact your physician at once.
for Disease Control, Division of Parasitic Diseases, Reviewed
March 2001, www.cdc.gov
Drinking Water Inspectorate Fact Sheet--Acanthamoeba, Fact Sheet
No. 11: Issue No. 1 March 1997 ©Crown Copyright 1996 www.awwarf.com
copyright Ken Ramos, 2004. All rights reserved.
is a retired U.S. Navy, Petty Officer. He now calls Western North
Carolina home, the city of Rutherfordton, after 21 yrs. of naval
service. Although his new home has not a "flight deck"
or aircraft landing overhead while he is trying to sleep, he is
coping fine. His interests lie in the study of Nature and Microorganisms,
chiefly Protozoa and as an amateur, is currently researching infectious
diseases associated with Protozoa. Leisure activities include
fly tying and fly fishing for trout in the mountain streams of
Western North Carolina and wilderness hiking.