Ebola hemorrhagic fever is a severe, often-fatal disease in humans and nonhuman primates (monkeys, gorillas,and chimpanzees) that has appeared sporadically since its initial recognition in 1976. The disease is caused byinfection with Ebola virus, named after a river in the Democratic Republic of the Congo (formerly Zaire) in Africa,where it w as first rec ognized. T he virus is o ne of two members of a family of RNA viruses called the Filoviridae .There are four identified subtypes of Ebola virus. Three of the four have caused disease in humans: Ebola-Zaire,Ebola-Sudan, and Ebola-Ivory Coast. The fourth, Ebola-Reston, has caused disease in nonhuman primates, butnot in humans.
The exact origin, locations, and natural habitat (known as the "natural reservoir") of Ebola virus remain unknown.However , on th e bas is of available evidence and the nature of sim ilar viruses , researchers believe that the virus is zoonotic (animal-borne) and is normally maintained in an animal host that is native to the African continent. A similar host is probably associated with Eb ola-Reston which was isolated from infected cynoolgous monkeys that were imported to the United States and Italy from the Philippines. The virus is not known to be native to other continen ts, such as North America.
Confirmed cases of Ebola HF have been reported in the Democratic Republic of the Congo, Gabon, Sudan, the Ivory Coast, Uganda, and the Republic of the Congo. An individual with serologic evidence of infection but showing no apparent illness has been reported in Liberia, and a laboratory worker in England became ill as a result of an
accidental needle-stick. No case of the disease in humans has ever been reported in the United States. Ebola-Reston virus caused severe illness and death in monkeys imported to research facilities in the United States andItaly fro m th e Ph ilippine s; du ring th ese outb reak s, se vera l rese arch work ers b ecame infec ted w ith the virus , but d id
not become ill.Ebola hemo rrhagic fever typically appears in sporadic outbreak s, usually spread within a health-care setting (asituation k nown a s am plification). It is likely that s poradic , isolated ca ses oc cur as w ell, but go un recogn ized. Atable showing a chronological list of known cases and outbreaks is available below.
Infections with Ebola virus are acute. There is no carrier state . Because the natural reservoir of the virus is unknown, the manner in which the virus first appears in a human at the start of an outbreak has not been determ ined. Ho wever, re search ers hav e hypothe sized that the first patient becomes infected through contact with an infected anim al.
After the first case-patien tinan outbreak setting is infected , the virus can be trans mitted in se veralways . People can be exposed to Ebola virus from direct contact with the blood and/or secretions of an infected person. Thus, the virus is often spread through families and friends because they come in close contact with such secretions
when caring for infected persons. People can also be exposed to Ebola virus through contact with objects, such as needles, that have been contaminated with infected secretions.
No socomial transmission refers to the spread of a disease within a health-care setting, such as a clinic or hospital. It occurs frequently during Ebola HF outbreaks. It includes both types of transmission described above. In African health-care facilities, patients are often cared for without the use of a mask, gown, or gloves. Exposure to the virus has occurred whe n health care workers treated individuals with Ebola HF without wearing these types of protective
clothing. In addition, when needles or syringes are used, they may not be of the disposable type, or may not havebeen sterilized, but only rinsed before reinsertion into multi-use vials of medicine. If needles or syringes becomecontaminated with virus and are then reused, numerous people can become infected.
The exact origin, locations, and natural habitat (known as the "natural reservoir") of Ebola virus remain unknown.However , on th e bas is of available evidence and the nature of sim ilar viruses , researchers believe that the virus is zoonotic (animal-borne) and is normally maintained in an animal host that is native to the African continent. A similar host is probably associated with Eb ola-Reston which was isolated from infected cynoolgous monkeys that were imported to the United States and Italy from the Philippines. The virus is not known to be native to other continen ts, such as North America.
Confirmed cases of Ebola HF have been reported in the Democratic Republic of the Congo, Gabon, Sudan, the Ivory Coast, Uganda, and the Republic of the Congo. An individual with serologic evidence of infection but showing no apparent illness has been reported in Liberia, and a laboratory worker in England became ill as a result of an
accidental needle-stick. No case of the disease in humans has ever been reported in the United States. Ebola-Reston virus caused severe illness and death in monkeys imported to research facilities in the United States andItaly fro m th e Ph ilippine s; du ring th ese outb reak s, se vera l rese arch work ers b ecame infec ted w ith the virus , but d id
not become ill.Ebola hemo rrhagic fever typically appears in sporadic outbreak s, usually spread within a health-care setting (asituation k nown a s am plification). It is likely that s poradic , isolated ca ses oc cur as w ell, but go un recogn ized. Atable showing a chronological list of known cases and outbreaks is available below.
Infections with Ebola virus are acute. There is no carrier state . Because the natural reservoir of the virus is unknown, the manner in which the virus first appears in a human at the start of an outbreak has not been determ ined. Ho wever, re search ers hav e hypothe sized that the first patient becomes infected through contact with an infected anim al.
After the first case-patien tinan outbreak setting is infected , the virus can be trans mitted in se veralways . People can be exposed to Ebola virus from direct contact with the blood and/or secretions of an infected person. Thus, the virus is often spread through families and friends because they come in close contact with such secretions
when caring for infected persons. People can also be exposed to Ebola virus through contact with objects, such as needles, that have been contaminated with infected secretions.
No socomial transmission refers to the spread of a disease within a health-care setting, such as a clinic or hospital. It occurs frequently during Ebola HF outbreaks. It includes both types of transmission described above. In African health-care facilities, patients are often cared for without the use of a mask, gown, or gloves. Exposure to the virus has occurred whe n health care workers treated individuals with Ebola HF without wearing these types of protective
clothing. In addition, when needles or syringes are used, they may not be of the disposable type, or may not havebeen sterilized, but only rinsed before reinsertion into multi-use vials of medicine. If needles or syringes becomecontaminated with virus and are then reused, numerous people can become infected.
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