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Epidemiologist: In Brazil, schistosomias

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Epidemiologist: In Brazil, schistosomias

by fiza gupta » Thu Mar 30, 2017 5:44 am
Epidemiologist: In Brazil, schistosomiasis and malaria are the two most common infectious diseases. Over the past five years, schistosomiasis has been primarily responsible for the overall increase in infectious disease cases. Therefore it is likely that there were more cases of schistosomiasis than malaria five years ago.

Which of the following most strengthens the argument above?

A)Over the past five years, the percentage of infectious disease cases caused by schistosomiasis has remained unchanged, but the percentage of cases caused by malaria has increased substantially.

B)Trends in infectious disease data tend to persist for decades, unless there is a major breakthrough in treatment regimens.

C)Five years ago, many more people died from schistosomiasis than died from malaria.

D)Over the past five years, the percentage of infectious disease cases caused by malaria was not significantly greater than the percentage of cases caused by schistosomiasis.

E)Over the past five years, the percentage of infectious disease cases caused by diseases other than malaria and schistosomiasis did not increase substantially.

OA:A
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by DavidG@VeritasPrep » Thu Mar 30, 2017 7:08 am
fiza gupta wrote:Epidemiologist: In Brazil, schistosomiasis and malaria are the two most common infectious diseases. Over the past five years, schistosomiasis has been primarily responsible for the overall increase in infectious disease cases. Therefore it is likely that there were more cases of schistosomiasis than malaria five years ago.

Which of the following most strengthens the argument above?

A)Over the past five years, the percentage of infectious disease cases caused by schistosomiasis has remained unchanged, but the percentage of cases caused by malaria has increased substantially.

B)Trends in infectious disease data tend to persist for decades, unless there is a major breakthrough in treatment regimens.

C)Five years ago, many more people died from schistosomiasis than died from malaria.

D)Over the past five years, the percentage of infectious disease cases caused by malaria was not significantly greater than the percentage of cases caused by schistosomiasis.

E)Over the past five years, the percentage of infectious disease cases caused by diseases other than malaria and schistosomiasis did not increase substantially.

OA:A
Conclusion: There were more cases of schistosomiasis than malaria five years ago.

Premise: Over the past five years, schistosomiasis has been primarily responsible for the overall increase in infectious disease cases.

Let's use some easy numbers to try to get a handle on the logic. Let's say that 5 years ago, there were 10 cases of illness. Today there are 20 cases of illness. (For simplicity's sake, let's say that these are distinct cases. In other words, of those 20 cases, none are people who have simply remained sick. They're new cases.

If schistosomiasis is the main driver, let's posit that 16 of those 20 new cases are instances of schistosomiasis, and 4 are malaria. So of the 20 new cases, 80% are schistosomiasis and 20% are malaria. We want to show that of those 10 original cases from five years ago, more are schistosomiasis.

A) If the percentage of infection disease cases caused by schistosomiasis has remained unchanged, then the percentage of schistosomiasis was 80% all along. And if the percentage of cases that are malaria has gone up, it means the percent was once lower than the current 20%. So let's say that five years ago, it was 10%. If that's true, there had to be more schistosomiasis cases than malaria cases five years ago. A is our answer.
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by DavidG@VeritasPrep » Thu Mar 30, 2017 7:09 am
(You can boil this down very quickly if you catch the logic without numbers. If a majority of the new cases are schistosomiasis, and the percentage of schistosomiasis cases is unchanged while malaria comprises a smaller percentage of the total number of cases, it's pretty clear that schistosomiasis was more common than malaria five years ago as well.)
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