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One of the most important organizations designed to combat fatal infectious diseases in poor countries goes by the unwieldy name

admin2013-07-02  66
问题     One of the most important organizations designed to combat fatal infectious diseases in poor countries goes by the unwieldy name of the Global Fund to Fight AIDS, Tuberculosis and Malaria. The link between the first two is well established. AIDS does not kill directly. Rather, the damage it does to the immune system opens an individual to other infections that would frequently be fought off by a healthy body. Of these, tuberculosis is one of the most important. Some 12% of deaths of people infected with HIV, the virus mat causes AIDS, are from tuberculosis, and, conversely, 16% of tuberculosis deaths are AIDS-related. The disease of malaria kills a lot of people — at least 1 million a year, although the exact figure is hard to come by — but there was little obvious medical connection between it and the other two.

    No longer. Over the past few years a number of studies have suggested mat those who are infected with HIV are more susceptible to malaria, and that the malaria parasite, in turn, raises the number of virus particles in those with HIV. Now, a study published in Science by Laith Abu-Raddad of the University of Washington, in Seattle, and his colleagues has tried to put some numbers on the problems.
    The study’s starting point is that the number of virus particles in the blood of someone infected with HIV increases about ten-fold during an attack of malaria. This seems to be due, paradoxically, to the immune system’s response to the malarial parasite. That response produces proteins called cytokines, which have the perverse effect of encouraging HIV to replicate.
    The increase in the number of virus particles is transient, and may do little harm to the individual’s own long-term prospects, but it does make him(or her)more likely to pass the infection on during sex. Conversely, the damage HIV does to the immune system means that the malarial parasite can more easily breed unchecked. That means people are more susceptible to infection in the first place, and that more parasites are available to be transmitted from person to person by the mosquitoes that spread them.     Dr. Abu-Raddad and his colleagues looked at past studies and came up with a set of numbers that can be plugged into a mathematical model they have developed of how, based on other papers, they think the diseases interact. They then applied the model to Kisumu, a part of Kenya that has a high prevalence of both diseases.
    The model suggests the peak of the HIV epidemic in Kisumu is 8% higher than what it would have been if there were no interaction between the diseases, while the peak level of malaria is 13% higher. Moreover, and in contrast to tuberculosis, where the peak lags seven years behind that of HIV, malaria peaked only one year after the peak of the HIV epidemic.
Malaria may increase the number of virus particles in the blood of individuals with HIV, because______.
选项 A、mosquitoes in the surroundings would transmit the virus from person to person
B、the damage to the immune system causes the blood susceptible to HIV virus
C、the response of immune system to malarial parasite may produce cytokines which may encourage HIV to replicate
D、malaria has a special trait to encourage HIV to breed quickly in the body
答案C
解析 事实细节题。有关疟疾会影响HIV数量增长的信息在文章的第三段。疟疾会使HIV数量成数十倍地增长，主要是因为免疫系统会对疟疾寄生虫产生反应，而这种反应生成的原浆蛋白质将会刺激HIV的繁殖。所以选项[C]正确。[A]只是使人类感染疟疾的原因之一，不是HIV病毒微粒数量增加的原因；[B]、[D]都不符合题干要求。
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