动物似乎是人类传染性疾病的主要来源体，通常60%人类的病原体来源于动物，而在新出现的疾病中，这一比例约在75%。

Animals seem to be the main source of new infectious disease in man: in general around 60% of human pathogens are transmissible from animals; among new diseases, the rate is about 75%.

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其中一些征兆和症状易于辨认，与病情相符，形成通常所称的综合征，说明存在一种或多种病原体。

Some of these signs and symptoms are easily recognizable and consistent, giving what is known as a syndrome that signals the presence of one or a number of pathogens.

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昆虫和病原体是森林生态系统的固有成分，通常其密度相对较低，所造成的损害较小，对树木生长及其活力的影响微乎其微。

Insects and pathogens are integral components of forest ecosystems and normally are present at a relatively low density, causing little damage, and having negligible impact on tree growth and vigour.

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Its molecules are pieces of molecules often derived from foreign pathogens which stimulate an immune response.

它通常是从激发免疫反应的,外源病原体中分离出的碎片

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