About the diseases

Here is a look at several diseases that are known to jump from animals to humans:

Ebola, a viral disease with a 50% fatality rate, was first discovered in 1976 when outbreaks struck in South Sudan and the Democratic Republic of Congo. The virus is transmitted through close contact with the blood, secretions, bodily fluids or organs of an infected human or animal. Symptoms begin with fever, fatigue, muscle pain and headache but can progress to vomiting, diarrhea, impaired kidney and liver function, sometimes even bleeding from gums or blood in the stool. The Ebola outbreak that began in 2014 hit hardest in Guinea, Liberia and Sierra Leone. All told, 28,600 people were sickened; 11,000 died. A patient returning to the U.S. from Liberia was diagnosed with the disease and died. Two health care workers who cared for the man subsequently developed Ebola, but recovered.

Middle East Respiratory Syndrome coronavirus is a viral respiratory disease first identified in Saudi Arabia in 2012. The transmission method is believed to be direct or indirect contact with infected dromedary camels. The disease does not pass easily from one human to another unless there is close contact. Some who are infected show no symptoms; others begin with fever, cough and shortness of breath. So far, there have been more than 2,100 laboratory-confirmed cases of the disease, including at least 733 deaths, according to the World Health Organization.

Severe Acute Respiratory Syndrome is a respiratory illness found in people and in civets, a small, nocturnal cat-like mammal. The disease is mainly passed through contact with infected saliva or droplets released by coughing. Symptoms begin with fever, body ache, headache, dry cough and difficulty breathing. Most patients develop pneumonia. SARS has been found in 26 countries, including China, Hong Kong, Singapore, Taipei, Vietnam, Canada and the U.S. The U.S. recorded eight laboratory-confirmed cases during a 2002-2003 outbreak.