據(jù)網(wǎng)友提供信息，2015年職稱英語考試衛(wèi)生B閱讀理解其中一篇來自于教材外。以下是試題原文。各位考友可以參考原文，比對答案。

1 You are likely aware that several countries in West Africa are battling an Ebola outbreak.Ebola is a dangerous and often lethal viral infection.Scientists believe that humans contracted the virus by eating the meat of rare animals.It is now believed that bats are the primary carries of the virus.

2 To date,there are only three major countries in West Africa experiencing a major outbreak:Sierra Leone,Liberia and Guinea.However,other countries such as Nigeria have reported confirmed cases of Ebola within their borders.

3 Unless you recently visited one of the three affected West countries you risk of contracting the virus is virtually zero.Unlike other recent airborne virus outbreaks like SARS,the Ebola virus can only be spread through direct contact with an infected person.Specifically,Ebola is spread through contact with body fluids.Though,the virus is transmittable,only an infected person exhibiting symptoms is communicable.

4 The signs and symptoms of Ebola are non-specific and patients typically exhibit them after a week of contracting the virus.Symptoms may appear as early as two days or as late as three weeks after initial infection.Symptoms include disgust,weakness and stomach pain.More uncommon symptoms include chest pain,bleeding and sore throat.

5 Ebola is devastating because of its ability to attack and replicate in every organ of the body.This causes an overstimulation of the body's inflammatory response,causing the flu-like symptoms.The virus also causes bleeding and impairs the body's normal clotting mechanism (凝血機制),making bleeding even more severe.Loss of blood volume and decreased organ perfusion (器官灌注)ultimately lead to organ failure and death.

6 The current outbreak is the deadliest viral outbreak in over 35 years.While diseases such as the malaria (瘧疾) are far more communicable,Ebola is one of the world's most fatal viral infections.Ebola's fatality rate exceeds that of SARS.