Mosquitoes May Spread Deadly Disease
Recently, in New York City dead crows were discovered and the
Bronx Zoo began losing some of its birds in captivity.
Initially this was very perplexing but tests on these birds,
and a New York City resident who died recently, confirmed that some
birds and mosquitoes in the New York City and Connecticut area are
infected with a West Nile-like virus.
This has resulted in a human encephalitis outbreak in that
area. Some mosquitoes and
birds continue to harbor this virus, however, the prevalence at this
time is not fully determined. Nevertheless,
many precautions and eradication measures are underway there to
prevent further transmission and toll of this disease.
The West Nile virus is closely related to the St. Louis encephalitis
virus and both are transmitted by the same mosquito species.
Although humans, birds and mosquitoes can become infected with
these viruses, they are only transmitted by mosquitoes that have fed
upon infected birds. The
West Nile-like virus is not transmitted from person to person or from
birds to persons. At this
point, it is not clear how the West Nile-like virus made its way to
the western hemisphere, and especially the United States, as it has
never before been recognized here.
There are many different types of organisms that may cause
inflammation or infection of the brain and/or its surrounding
membranes. Generally,
when one becomes ill from a viral infection of the brain this is
called encephalitis; whereas, when a highly destructive bacterial
infection of the brain occurs, preceding abscess formation, this is
called cerebritis. Each
of these conditions may cause diffuse or focal encephalopathy
(abnormal brain function).
There are many different viruses that may cause encephalitis and each
requires a portal of entry into the body and ultimately into the
brain. Some viruses are
transmitted by humans and others by mosquitoes or ticks that inoculate
their victim with an arbovirus. Rabies
is also caused by a virus; however, this is generally transferred by
an animal bite. Each of
these viruses replicate outside of the brain and then gain entry
either by spreading through the blood or along the nerves that connect
to the brain. Once within
the brain the virus enters the nerve cells, disrupting normal cell
function and ultimately causing permanent injury or death.
All arboviruses require an insect to transmit the infection from one
host to another and in the United States this is more likely to occur
between June and October. Most
of the viruses that cause encephalitis do not seem to have a
predilection for men or women; however, they each seem to have a
predilection for people of certain age groups.
Generally individuals at the extremes of age are at the highest
risk and certainly anyone with a compromised immune system due to
other illness is a prime victim.
Encephalitis causes encephalopathy and this often results in
behavioral or personality changes, decreased consciousness, seizures,
confusion or amnesia as well as headache and stiff neck.
The Center for Disease Control has suggested that when outdoors, to
reduce contact with mosquitoes, wear clothing that covers the skin
such as long sleeves, shirts and pants and spray clothing and exposed
skin with insect repellant. Curb
activities outside at dawn, dusk and during the evening when
mosquitoes tend to feed. Further,
they recommend continuing individual and community efforts to control
or prevent mosquito breeding.
Clinically, it is important to distinguish and quickly
diagnose these conditions as each may cause permanent brain damage or
even death. Swift
identification and treatment may be lifesaving. |
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