Ebola virus is one of a group of viruses that cause a hemorrhagic fever syndrome. Symptoms of Ebola virus infection are similar to those produced by other hemorrhagic fever viruses and include fever, fatigue, malaise, reddened eyes, weakness, joint pain, muscle pain, headache, nausea, vomiting, and diarrhea. Patients experience a loss of appetite and often stomach pains. Some patients experience sore throat, rash, cough, hiccups, chest pain, breathing problems, and difficulty swallowing. Later, as the disease progresses and worsens in severity, symptoms can include bleeding at various sites within or outside of the body.