Реферат: Ebola Hemoragic Fever Essay Research Paper Viral
Ebola Hemoragic Fever Essay, Research Paper
Viral hemorrhagic fevers are a group of diseases caused by viruses from four families of viruses: filoviruses, arenaviruses, flaviviruses, and bunyaviruses. The usual hosts for most of these viruses are rodents or arthropods (such as ticks and mosquitoes). In some cases, such as Ebola virus, the natural host for the virus is unknown. All forms of viral hemorrhagic fever begin with fever and muscle aches. Depending on the particular virus, the disease can progress until the patient becomes very ill with respiratory problems, severe bleeding, kidney problems, and shock. The severity of viral hemorrhagic fever can range from a mild illness to death.
The Ebola virus is a member of a family of RNA viruses known as filoviruses. Ebola virus was discovered in 1976 and was named for a river in Zaire, Africa, where it was first found.
Until recently, only three outbreaks of Ebola hemorrhagic fever among people had been reported. The first two outbreaks were in 1976: one in Zaire and one in western Sudan. These were large outbreaks, causing more than 550 cases and 340 deaths. The third outbreak, in 1979 in Sudan, was smaller, with 34 cases and 22 fatalities. During each of these outbreaks, a majority of cases occurred in hospital settings under the challenging conditions of the developing world. These conditions, including a lack of medical supplies and the frequent reusing of needles and syringes, played a major role in the spread of disease. The outbreaks were quickly controlled when appropriate medical supplies and equipment were made available and quarantine procedures were used.
The source of the Ebola virus in nature remains unknown. In an attempt to identify the source, investigators tested thousands of specimens from animals captured near the outbreak areas, but their efforts were unsuccessful. Monkeys, like humans, appear to be susceptible to infection. The one thing knowne by scientists which may bring us closer to discovering its carrier is that Ebola falls into the category of filoviruses. Filoviruses are typically carried by rodents and arthropods (ticks, mosquitos).
Symptoms of Ebola hemorrhagic fever begin 4 to 16 days after infection. Persons develop fever, chills, headaches, muscle aches, and loss of appetite. As the disease progresses, vomiting, diarrhea, abdominal pain, sore throat, and chest pain can occur. The blood fails to clot and patients may bleed from injection sites as well as into the gastrointestinal tract, skin, and internal organs.
Ebola virus is spread through close personal contact with a person who is very ill with the disease. In previous outbreaks, person-to-person spread frequently occurred among hospital care workers or family members who were caring for an ill person infected with Ebola virus. Transmission of the virus has also occurred as a result of hypodermic needles being reused in the treatment of patients. Reusing needles is a common practice in developing countries, such as Zaire and Sudan, where the health care system is underfinanced. Medical facilities in the United States do not reuse needles.
Ebola virus can also be spread from person to person through sexual contact. Close personal contact with persons who are infected but show no signs of active disease is very unlikely to result in infection. Patients who have recovered from an illness caused by Ebola virus do not pose a serious risk for spreading the infection. However, the virus may be present in the genital secretions of such persons for a brief period after their recovery, and therefore it is possible they can spread the virus through sexual contact.
A diagnosis is made by detection of Ebola antigens, antibody, or genetic material, or by culture of the virus from these sources. Diagnostic tests are usually performed on clinical specimens that have been treated to inactivate (kill) the virus. Research on Ebola virus must be done in a special high-containment laboratory to protect scientists working with infected tissues.
Previous outbreaks of Ebola hemorrhagic fever have been limited. These outbreaks were successfully controlled through the isolation of sick persons in a place requiring the wearing of mask, gown, and gloves; careful sterilization of needles and syringes; and proper disposal of waste and corpses.
Hospital personnel isolate ill persons through a method called “barrier technique.” Barrier technique includes the following actions: 1) doctors and nurses wear gowns, mask, gloves, and goggles when caring for patients; 2) the patient’s visitors are restricted; 3) disposable materials are removed from the room and burned after use; 4) all reusable materials are sterilized before reuse; and 5) since the virus is easily destroyed by disinfectants, all hard surfaces are cleaned with a sanitizing solution.
In 1995 there was an outbreak of ebola in Kikwit. Eight patients were given a blood transfusion using the blood of ebola survivors. Although seven out of the Eight patients survived the results were not taken seriously on account that the patients’ symptoms predisposed them to recovery.
Studys conducted in the central African Republic presented Plasma samples from 5 different zones of Africa. 21.3% of the plasma samples collected showed anti-bodies to the ebola virus as being present. Place of residence has allot to do with exposure to filoviruses such as ebola, as is shown in these studys. 37.5% of hunter gatherers living in the forests of Africa tested positive for anti bodies. Where as only 13.2 of farmers, who live in a slightly less rural environment tested positive.
What this shows us is that people in less sophisticated parts of the world are more susceptible to these sort of viruses. This is do to poor sanitation such as lack of indoor plumbing. Once these viruses have began to spread they are not easily contained in these third world conditions.