Although genetic mutations in bacteria and viruses
can lead to epidemics, some epidemics are caused
by bacteria and viruses that have undergone no
significant genetic change. In analyzing the latter,
(5) scientists have discovered the importance of social
and ecological factors to epidemics. Poliomyelitis,
for example, emerged as an epidemic in the United
States in the twentieth century; by then , modern
sanitation was able to delay exposure to polio until
(10) adolescenceor adulthood, at which time polio
infection produced paralysis. Previously, infection
had occurred during infancy, when it typically
provided lifelong immunity without paralysis. Thus,
the hygiene that helped prevent typhoid epidemics
(15) indirectly fostered a paralytic polio epidemic.
Another example is Lyme disease, which is caused
by bacteria that are transmitted by deer ticks. It
occurred only sporadically during the late
nineteenth century but has recently become
(20) prevalent in parts of the United States, largely due
to an increase in the deerpopulation that occurred
simultaneously with the growth of the suburbs and
increased outdoor recreationa l activities in the
deer's habitat. Similarly, an outbreak of dengue
(25) hemorrhagic fever became an epidemic inAsia in
the 1950s because of ecological changes that
caused Aedes aegypti, the mosquito that transmits
the dengue virus, to proliferate. The stage is now
set in the United States for a dengue epidemic
(30) because of the inadvertent introduction and wide
dissemination of another mosquito, Aedes albopictus.
The passage suggests that a lack of modern sanitation would make which of the following most
likely to occur?
(A) An outbreak of Lyme disease
(8) An outbreak of dengue hemorrhagic fever
(C) An epidemic of typhoid
(D) An epidemic of paralytic polio among infants
(E) An epidemic of paralytic polio among adolescents and adults
can lead to epidemics, some epidemics are caused
by bacteria and viruses that have undergone no
significant genetic change. In analyzing the latter,
(5) scientists have discovered the importance of social
and ecological factors to epidemics. Poliomyelitis,
for example, emerged as an epidemic in the United
States in the twentieth century; by then , modern
sanitation was able to delay exposure to polio until
(10) adolescenceor adulthood, at which time polio
infection produced paralysis. Previously, infection
had occurred during infancy, when it typically
provided lifelong immunity without paralysis. Thus,
the hygiene that helped prevent typhoid epidemics
(15) indirectly fostered a paralytic polio epidemic.
Another example is Lyme disease, which is caused
by bacteria that are transmitted by deer ticks. It
occurred only sporadically during the late
nineteenth century but has recently become
(20) prevalent in parts of the United States, largely due
to an increase in the deerpopulation that occurred
simultaneously with the growth of the suburbs and
increased outdoor recreationa l activities in the
deer's habitat. Similarly, an outbreak of dengue
(25) hemorrhagic fever became an epidemic inAsia in
the 1950s because of ecological changes that
caused Aedes aegypti, the mosquito that transmits
the dengue virus, to proliferate. The stage is now
set in the United States for a dengue epidemic
(30) because of the inadvertent introduction and wide
dissemination of another mosquito, Aedes albopictus.
The passage suggests that a lack of modern sanitation would make which of the following most
likely to occur?
(A) An outbreak of Lyme disease
(8) An outbreak of dengue hemorrhagic fever
(C) An epidemic of typhoid
(D) An epidemic of paralytic polio among infants
(E) An epidemic of paralytic polio among adolescents and adults
Fiza Gupta
