الفهرس 
History and epidemiology of EBOLA Virus DiseaseOnly 14 pages are availabe for public view
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Abstract
Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever is a severe, often fatal illness in humans. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission. The average EVD case fatality rate is around 50%.
The Ebola virus causes an acute, serious illness which is often fatal if untreated. Ebola virus disease (EVD) first appeared in 1976 in two simultaneous outbreaks, one in what is now, Nzara, South Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name. The outbreak in West Africa, (first cases notified in March 2014), is the largest and most complex Ebola outbreak.
The virus family Filoviridae includes two genera: Marburg virus, and Ebola virus. There are five species that have been identified: Zaire, Bundibugyo, Sudan, Reston and Taï Forest. The virus causing the 2014 West African outbreak belongs to the Zaire species.
Transmission:
It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is introduced into the human population through close contact with the blood, secretions, organs or other body fluids of infected animals such as chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rain forest. Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other body fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.
Health-care workers have frequently been infected while treating patients with suspected or confirmed EVD. This has occurred through close contact with patients when infection control precautions are not strictly practiced. People remain infectious as long as their blood contains the virus.
Symptoms of Ebola virus disease:
The incubation period is 2 to 21 days. Humans are not infectious until they develop symptoms. First symptoms are the sudden onset of fever, fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal and external bleeding (e.g. oozing from the gums, blood in the stools). Laboratory findings include low white blood cell and platelet counts and elevated liver enzymes.
Diagnosis:
It can be difficult to distinguish EVD from other infectious diseases such as malaria, typhoid fever and meningitis. Confirmation made using the following investigations:
• antibody-capture enzyme-linked immunosorbent assay (ELISA)
• antigen-capture detection tests
• reverse transcriptase polymerase chain reaction (RT-PCR) assay
• electron microscopy
• Virus isolation by cell culture.
Samples from patients are an extreme biohazard risk; samples should be conducted under maximum biological containment conditions.
Treatment and vaccines
Supportive care, rehydration with oral or intravenous fluids and treatment of specific symptoms improves survival. There is as yet no proven treatment available for EVD. However, a range of potential treatments including blood products, immune therapies and drug therapies are currently being evaluated. No licensed vaccines are available yet, but two potential vaccines are undergoing human safety testing.
Prevention and control
Good outbreak control relies on applying a package of interventions such as case management, surveillance and contact tracing, a good laboratory service, safe burials and social mobilization. Raising awareness of risk factors for Ebola infection and protective measures that individuals can take is an effective way to reduce human transmission. Risk reduction messaging should focus on several factors:
1. Reducing the risk of wildlife-to-human transmission
2. Reducing the risk of human-to-human transmission
3. Outbreak containment measures
Controlling infection in health-care settings:
Health-care workers should always take standard precautions when caring for patients. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment and safe injection practices. But with suspected or confirmed Ebola virus they should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding. When in close contact of patients with EBV, health-care workers should wear face protection, a clean, non-sterile long-sleeved gown, and gloves (sterile gloves for some procedures).
Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Ebola infection should be handled by trained staff and processed in suitably equipped laboratories.