Biomedical Engineering Reference
In-Depth Information
22.1
Introduction
22.1.1
Hanta Virus
Hanta virus cardiopulmonary syndrome (HCPS) is a severe life-threatening illness that
was first recognized in the spring of 1993. More than 202 cases have been confirmed in 30
states, since the 1993 outbreak, 45% of the cases being fatal. Most of the incidences of the
infection have occurred in the western United States. HCPS is caused by several closely
related yet genetically distinct Hanta virus species, each of which is maintained in a sin-
gle rodent host [1]. In the United States, the causative agent for the vast majority of cases
is the Sin Nombre virus (SNV), which is transmitted to human beings from the deer mouse
(
Peromyscus maniculatus
), its primary rodent reservoir. Inhalation of aerosolized virus par-
ticles excreted in rodent urine, saliva, or feces is believed to be the major route of trans-
mission, although infection can also occur by means of direct inoculation of the virus into
wounds or by bite.
SNV (genus of the family Bunyaviridae) was identified during a 1993 outbreak of an
acute respiratory disease with high mortality in the Four Corners region of the south-
western United States (New Mexico, Utah, Colorado, and Arizona) [2]. HCPS occurs in
humans presumably after accidental/incidental inhalation of virus-contaminated excre-
tion from the natural host, the deer mouse (
P. maniculatus
). Although the deer mouse has
been determined to be the primary reservoir of the Hanta virus in many areas of North
America, serologic evidence of infection has also been found in other mammals. The
illness is characterized by flulike symptoms, fever, rapid-progressing pulmonary edema,
significant increase in hematocrit, and a decrease in platelets. The infection is spread by
aerosolized excreta and transmission to humans occurs under the conditions of close
contact with the rodent host [3]. While a few cases of HCPS have been reported in the
urban East, the predominant case distribution is in the rural West. Exposure and infection
most often occurs in rural areas remote from medical centers with sophisticated diagnos-
tic capabilities.
22.1.2
Avian Influenza
Avian influenza (AI) is an infectious disease of birds caused by type A strains of the
influenza virus. The disease, which was first identified in Italy more than 100 years ago,
occurs worldwide. From a biotechnology standpoint, the AI is an interesting topic due to
the mutating capabilities of the influenza virus. By gaining an intuitive understanding on
how the avian virus works, we can confront the virus head on and prevent the occurrence
of a pandemic. Vaccines may be produced, which in effect will kill the invading virus in
our body without any harmful effects to our own immune system [4].
It is necessary to determine the rate at which the avian virus is capable of mutating and
spreading. By deriving an appropriate model for the virus, it is possible to determine the
governing factors on how and why the virus spreads. From this data, it will then be pos-
sible to slow down the rate at which the virus spreads, which in turn prevents the virus
from getting out of control.
All birds are thought to be susceptible to infection with AI, although some species are
more resistant to infection than others. Infection causes a wide spectrum of symptoms in
birds, ranging from mild illness to a highly contagious and rapidly fatal disease resulting
in severe epidemics. The latter is known as “highly pathogenic AI”. This form is charac-
terized by sudden onset, severe illness, and rapid death, with a mortality that can
approach 100%. According to Centre for Health Protection (CHP) [4], 15 subtypes of
