Virus typing Four subtypes of Ebola virus have been identified, namely Ebola-Zaire (EBO-Zaire), Ebola-Sudan (EBO-Sudan), Ebola-Leston (EBO-R), and Ebola-Côte d’Ivoire (EBO-CI).EBO-Z and EBO-S are highly pathogenic and lethal to humans and nonhuman primates; EBO- R is not pathogenic to humans and has a lethal effect on nonhuman primates; EBO-CI is clearly pathogenic to humans but generally not lethal and is highly lethal to chimpanzees. 1. Zaire Ebola virus Zaire Ebola virus has a lethality rate of up to 90%, with mortality rates in endemic areas of 88% in 1976, 100% in 1977, 59% in 1994, 81% in 1995, 73% in 1996, 80% from 2001 to 2002, and 90% in 2003, with an average of 83% in 2007. The first outbreak was recorded on August 26, 1976, in the northern town of Zaire, with the first case of Mabalo Lokela, a 44-year-old teacher, who was diagnosed with a high fever as a suspected malaria infection and treated with quinine injections, The patient began to bleed from the mouth, nose, rectum and other places and passed away on September 18, after only about 2 weeks of illness. Soon after, more patients presented to the doctor with similar symptoms, including fever, headache, muscle pain, joint pain, fatigue, nausea, and dizziness. These often develop into bloody diarrhea, severe vomiting and multiple hemorrhages. The initial infection may be caused by the repeated use of used but unsterilized syringes, and the subsequent infection is mainly due to the infestation of the virus when caring for patients without proper safety measures or the cleaning process of traditional burial prep work. 2, Sudanese Ebola virus Sudanese Ebola virus was first discovered in 1976 in a Sudanese cotton factory worker. Researchers noted that the worker should have been exposed to the carrier host in or near the factory, but after testing animals and insects near the factory nothing was found, and the carrier host is still unknown. The second case was a nightclub manager living in Sudan, who was treated by the local hospital by all means to no avail, and was finally pronounced dead. The medical staff did not take proper precautions when treating him, resulting in a major outbreak of the virus spreading throughout the hospital. The most recent outbreak occurred in May 2004, when 20 cases were reported in Yambio County, Sudan, and five people died. The average mortality rate of Ebola in Sudan was 53% in 1976, 68% in 1979, and 53% between 2000 and 2001, with an average mortality rate of 53.76%. 3. Reston Ebola virus was first detected in November 1989 in a group of crab-eating monkeys imported from the Philippines to Reston, Virginia, USA. This virus is highly lethal to monkeys, but not to humans. In February 1990, there was another outbreak of Reston Ebola in Reston, Texas and the Philippines, and in 1992 and 1996, more cases were found in Tuscany, Italy and Texas. All infected monkeys showed only symptoms similar to those of simian hemorrhagic fever. In both outbreaks, no humans were infected. 4. Ebola virus in Côte d’Ivoire The species Ebola virus in Côte d’Ivoire was first identified in the Taï National Park in Côte d’Ivoire. On November 1, 1994, the bodies of two chimpanzees were found in the forest. The examiners found brown and liquefied blood in the heart (blood in a corpse should normally clot completely after a dozen hours of death), no visible signs of internal organs, and lungs filled with blood. Tissue taken from chimpanzees showed that the virus was very similar to Sudanese Ebola and the 1976 outbreak of Zairean Ebola. After 1994, more dead chimpanzees were found and scientists tested for the virus using many methods. The source of the infection is thought to be a colobus monkey that was preyed upon by chimpanzees and carried the virus. One of the scientists performing the post-mortem examination became infected with the virus. She developed dengue-like symptoms and was sent to Switzerland for treatment a week later. She was discharged from the hospital two weeks later and fully recovered by the sixth week after contracting the virus.