81. The passage suggests that a lack of modern sanitation would make ____ most likely to occur.

1. an epidemic of paralytic polio among adolescents and adults
2. an outbreak of dengue hemorrhagic fever
3. an epidemic of typhoid
4. an epidemic of paralytic polio among infants

82. According to the passage, the outbreak of dengue hemorrhagic fever in the 1950s occurred for the reason that ____.

1. the mosquito Aedesaegypti was newly introduced into Asia
2. the mosquito Aedesaegypti became more numerous
3. the mosquito Aedesalbopictus became infected with the dengue virus
4. more people began to visit and inhabit areas in which mosquitoes live and breed

83. It can be inferred from the passage that Lyme disease has become prevalent in parts of the United States because of ____.

1. the inadvertent introduction of Lyme disease bacteria to the United States
2. the inability of modern sanitation methods to eradicate Lyme disease bacteria
3. a genetic mutation in Lyme disease bacteria that makes them more virulent
4. an increase in the number of humans who encounter deer ticks

84. Which of the following can most reasonably be concluded about the mosquito Aedesalbopictus based upon the passage?

1. It is native to the United States.
2. It can proliferate only in Asia.
3. It transmits the dengue virus.
4. It caused an epidemic of dengue hemorrhagic fever in the 1950s.

85. Which of the following, if true, would most strengthen the author's assertion about the cause of the Lyme disease outbreak in the United States?

1. The deer population was smaller in the late 19th century than in the mid-20th century.
2. Interest in outdoor recreation began to grow in the late 19th century.
3. In recent years the suburbs have stopped growing.
4. Scientists have not yet developed a vaccine that can prevent Lyme disease.

(Reference keys.)