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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  87
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.
What can be inferred from the passage?
选项 A、AIDS may be most prevalent in African countries.
B、The mosquito is a main means of malarial parasite transmission.
C、Interaction between diseases can cause a negative effect.
D、The mathematical model is only a hypothesis till now.
答案C
解析 推理判断题。文章只提到Kisumu是Kenya艾滋病和疟疾发病率最高的地区，由此断定[A]的内容过于武断。原文只是说蚊子会传播疟疾寄生虫，而没有说它是一种主要传播途径，故排除[B]。在文章最后一段列举的数据中可以看出，交互作用使发病率明显升高，所以[C]正确。[D]与文中所说事实不符。
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