For every dollar invested in worm control and prevention, African countries see up to 42 dollars return in economic benefits.

每在蠕虫控制和预防上投入一美元，非洲国家就能获得高达 42 美元的经济回报。

Then if Sterling strengthened against the dollar, that's actually a negative because it diminishes the sterling value of that dollar return.

那么，如果英镑兑美元走强，这实际上是负面的， 因为它会降低美元回报的英镑价值。