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Ebola virus damage overview

In 1976, in southern Sudan and the Democratic Republic of the Congo (formerly Zaire) serious contagious haemorrhagic fever broke out almost simultaneously in the North, CFR 53% and 88%. Who expert from patients specimens in the separation to a new of filamentous virus, form Shang and Marburg virus similar, but immune features different, then to found to democratic Congo of Egyptian Bo pulled River named, called Egyptian Bo pulled virus [1,2], by raised of disease called Egyptian Bo pulled hemorrhagic fever (EBHF), has global has infection onset near 2000 cases, death more than 1000 more cases, fatality rate up 53%~88%. This article an overview to Ebola virus and its harm.

1 the Ebola virus [3~6]

1.1 structure of the Ebola virus (EBV) is a filovirus, filaments in a long, single-stranded negative-strand RNA viruses, there were 18,959 base, and a molecular weight of 4.17×106. Outside the capsule, the virus particle about 80nm in diameter, size 100nmx (300~1500) NM, virus infected ability long (665~805) about NM, a branch-shaped, u-shaped, 6-shaped or circular, branching is common. Herpesviridae, the surface (8~10) nm long spike. Pure ribose virus particle consists of a spiral core-shell composite structure with linear chain 4 virion structural proteins and RNA molecules.

1.2 parting has already identified the virus divided into 4 subtypes of the Ebola virus, Ebola-Zaire (EBO-Zaire), Ebola-Sudan (EBO-Sudan), Ebola-Reston type (EBO-R) and Ebola-Ivory Coast (EBO-CI). Different subtypes have different characteristics, EBO-Z and EBO-S for human and non-human primates in virulence and mortality rate is very high; EBO-R not pathogenic to humans, has lethal effects on non-human primates; EBO-CI are significantly pathogenic to humans, but are generally not lethal, chimpanzee death rate is very high.

Physicochemical properties and resistance to EBV 1.3 stable at room temperature, heat moderate resistance, 56 cannot be completely inactivated, 60 30min to destroy the infectious; ultraviolet light 2min can make it completely inactivated. Sensitive to chemicals, ethyl ether, sodium deoxycholate, β-propiolactone, formalin, sodium hypochlorite disinfectant can be completely inactivated viral; cobalt-60 radiation, gamma rays can also make it inactivated. EBV in blood samples or disease in the body that can survive for several weeks; 4 ℃ for 5 weeks its infectivity remains unchanged, titer of 8 weeks reduced by half. -70 ℃ long-term preservation.

1.4 sensitive animals and cells

1.4.1 sensitive animals susceptible to various non-human primates generally, non-gastrointestinal tract or nasal route through the intestinal tract, can cause infection, 2-5 days after infection with high fever, 6-9-day mortality. 1-4 days of onset until death, blood containing the virus.

Guinea pigs, hamsters, mice are less sensitive, Intraperitoneal, intravenous, subcutaneous or intranasal inoculation of channels can cause infection. Adult mice and Chick embryos is not sensitive.

1.4.2 sensitive green monkey kidney cells (Vero), primary Hamster kidney cells (BHK), are available in human embryo lung fibroblasts culture EBV. 7h after virus-infected cells, cultured virus can be detected in RNA,18h, peaked at 48h can see cell lesions. 7-8 days after cell rounding, shrunken, stained virus inclusion bodies within cells.

2 epidemiological characteristics of Ebola haemorrhagic fever

2.1 distribution [3,6] Ebola hemorrhagic fever so far shows endemic, restricted to the rainforests of Central Africa and Eastern and Southern African Savannas, but has been extended from the beginning of the Sudan, the Democratic Republic of the Congo to the Republic of Congo, Central African Republic, Libya, Gabon, Nigeria, Kenya, Ivory Coast, Cameroon, Zimbabwe, Uganda, Ethiopia, and South Africa. Occasional case reports outside of Africa, are imported or infection of laboratory accidents, found no Ebola haemorrhagic fever epidemics.

2.1.1 endemic [6~10] incidence more than 30 cases of epidemic in Africa at least eight times.

First: 1976 6 November. Southern Sudan, the total incidence of 284 cases and 151 deaths, mortality is 53%. 1976 9 October in the Democratic Republic of Congo (formerly Zaire) Zaire region, 318 cases were detected, 280 cases of mortality, mortality 88%. 85 cases of infection of their shared syringes, secondary health care and patients ‘ relatives.

Second: the nzara area in Sudan in 1979, the incidence of 33 cases, 22 cases of death, mortality is 67%.

Third: Ming Kebo, Makokou in Gabon in June 1994 and gold mining in the rainforest region, the incidence of 49 cases and 31 deaths and CFR 63%.

Fourth: April 1995 occurred in the Democratic Republic of Congo Kikwit and surrounding areas, the incidence of 315 cases, 245 cases of death, mortality 77%. Secondary case for treatment and care staff, 25% per cent of all cases.

Fifth: the year from February 1996 to January in northern Gabon, incidence 60 cases and 45 deaths and CFR 75%. 66/97 prevalence to contact 1 chimpanzee 21 villagers died in the jungle, secondary cases attend the burial traditions of the dead.

Sixth: August 2000-January ~2001 years in the northern Ugandan districts of Gulu, Masindi and Mbarara. Total incidence of 425 cases, 224 cases of death, mortality 53%.

Seventh: October 2001 ~ March in the Republic of Congo and Gabon, a total of 123 cases of onset, 97 cases of mortality, mortality is 79%.

Eighth: December 2002 during the end of April, the Congo a total of 143 cases of infection, mortality in 128 cases, CFR 89%. Prevalent reason of hunting-related activities, contact infection with chimps and other mammals.

Most recently for 2005 4 June, in the Congo (Brazzaville) in 12 cases, 9 cases were found dead. Confirmed by autopsy after sampling [7].

2.1.2 other case report [6] (1) the endemic areas of infection, incidence of remote. To date, United Kingdom, and Switzerland reported imported cases, both travel in the popular area, involved in the diagnosis and treatment of patients or researchers in the survey. Not popular. (2) laboratory. Ebola lab reports clearly so far infected at least 2 times a 1976 United Kingdom Institute of Microbiology Porton Down (RME), a transferring staff the laboratory of Ebola infection in Guinea pig liver homogenates infected pierced the thumb clockwise head. Another in May 2004, Russia Victor laboratory, a scientist accidentally infected syringe needles pricked fingers, infections died.

2.2 natural host [the natural reservoir of 3]EBV, though not yet finalized, but so far, there have been multiple lines of evidence show that wild non-human primates such as monkeys and apes and other animals in EBV infection. Exhibit 1: 1976, 1996 and 2002 epidemic, deaths resulting from human exposure to the wild Gorilla; 2 evidence: the Philippines exports monkeys repeatedly to detect EBV, but found no disease; evidence 3: in August 2003, Congo (Brazzaville) Ministry of health survey showed that chimpanzees in the wild boar can be found in the body to the EBV.

2.3 infectious and spreading human cases of Ebola infection is primarily a patient. Human-human contact plays an important role. Route of transmission is airborne and is in direct contact with the patient. Contact with blood, secretions and excretions, and contaminated items can also be transmitted through contact. Patient care and one-fourth per cent of the total number of cases of infection. Re-using effective disinfection of syringes triggered in 1976 EBHF outbreak in the Democratic Republic of Congo, but fashion does not play a significant role in recent years.

2.4 incubation period human infection with EBV to onset of incubation period is 7-16 days.

2.5 susceptible and susceptible to high-risk populations generally, regardless of their age and gender. High-risk populations include Ebola hemorrhagic fever patients, persons in close contact with the infected animals such as medical personnel, inspection personnel, personnel in the Ebola epidemic, and so on.

2.6 pathogenic EBV can infect many mammals such as humans, monkeys and Guinea pigs, wild boars, highly contagious. With humans, chimps fatal high. Pathogenicity of different type of EBV is different, with Zaire-the strongest, followed by Sudan, is the major disease-causing disease in humans. Reston-only on primates in Africa cause disease, and does not have the disease in humans were reported. Virulence is weak, that may exist in nature do not cause disease of Ebola virus, because in some parts of Africa the normal antibody-positive rate of 30%, and no episode.

3 clinical manifestation and laboratory examination [3~5]

3.1 clinical manifestations of sudden onset, fever with severe headaches, eye conjunctiva hyperemia, sore throat with prominent odynophagia, muscle and joint pains, aches, and marked anorexia and extreme exhaustion. 2-3 days after onset, nausea, abdominal pain, diarrhea, stool mucous or bloody stool. Soon found bleeding, uneven, hemoptysis and epistaxis, hematemesis or/and injection site bleeding and hematoma. 5-7 days there may be characteristics of measles-like rash or rash, eyebrows and hands over more common recovery with desquamation. Some patients with neurological involvement, characterized by mood disorders, disturbance of consciousness and meningeal irritation, persisting until the recovery period. Hemorrhage is the main cause of death in EBHF, but the majority of patients died of liver and kidney failure and fatal complications. Sudan EBV infection with respiratory symptoms, long course, but the mortality rate is low.

3.2 duration of disease stage is generally divided into three stages.

3.2.1 early as non-specific symptoms, including fever, weakness, diarrhea, nausea, headache, muscle aches, back pain and maculopapular rash appears, two important features of bilateral conjunctival bleeding and swelling caused by the sounds they are sore.

3.2.2 after 2-3 days of late characterized by extensive bleeding both inside and outside the human body, finally appear in oral, nasal, anal bleeding and other symptoms, but died in 24h due to hemorrhagic shock in a coma.

3.2.3 the recovery period after the onset of 10-12 days, and persistent fever declined, his condition gradually improved into the recovery period will take about 5 weeks or longer.

3.3 indicators of pathogens and infected test [3,4,10,11]

3.3.1 sample detection and separation of pathogens: the acute phase (onset within 8 days) of whole blood, excretions and secretions, as well as an autopsy of the deceased tissue and organ specimens.

The detection antibody: within 8 days after the onset of acute phase sera, after 14 days of convalescence serum.

3.3.2 testing method to check for pathogens and antigens. virus isolation test (1) cells inoculated isolates, such as Vero, MA-104, BHK-21, and so on. Generally the acute stage in patients ‘ blood, urine, or autopsy tissue suspension direct inoculation of susceptible cells. Then using Polyclonal antiserum or virus-specific monoclonal antibody, by indirect immunofluorescence assay (IFA) or other specific immunological detection methods for identification. (2) vaccination of animals, viruses isolated Guinea pig and rat method is often used. The above material inoculated animals, after the onset of animal viruses and antigens in the blood, tissue and organ. causative morphology electron microscopic examination is one method for rapid diagnosis of EBV infection, used to directly examine the patient’s blood, urine, semen, sweat glands of the skin, as well as in the culture supernatant virus particles. nucleic acid detection by RT-PCR technique and specificity of nucleic acid probe hybridization. Currently, l, is based mainly on virus GP and NP gene encoding designed specific primers or nucleic acid probes, sensitivity and specificity of the serological Antigen detection method with higher than that in many EBHF used in the outbreak or epidemic. Combined with PCR product sequencing applications, you can diagnose and help to identify false-positive results due to cross contamination. immunological detection by indirect immunofluorescence assay (IFA), can be used to check serum, inoculation of cell and tissue samples from infected animals and patients.

Examined the application of antibody in the serum of convalescent patients and epidemiological investigation. Immunofluorescence Assay, positive serum antibodies of 1:16 to determine available IgM and (or) IgG.

In addition, solid indirect enzyme-linked immunosorbent assay test, as well as checks and testing can also be used to make antibodies.

4 Ebola haemorrhagic fever diagnosis and treatment [3~8]

4.1 identify the history of epidemiology 20 days ago, non-endemic areas of residence and travel history; there are no human or animal corpses, blood, secretions, excretions exposed as doctors, nurses, laboratory workers, and other professionals have no history of exposure to EBV.

4.2 differential diagnosis with Marburg Hemorrhagic fever, Lassa fever, Xinjiang (Crimean-Congo) differential diagnosis of hemorrhagic fever with, based on history, clinical features, epidemiology, and when necessary, virological, serologic tests to help diagnose.

4.3 criteria for diagnosis

4.3.1 suspected cases of patient history plus a further 2.7 3.1 epidemiology clinical manifestations, lack of virological or serological positive evidence.

4.3.2 confirmed cases suspected cases and virological or serological positive evidence.

4.4 drug treatment there is no specific treatment, interferon and the antiviral drugs against filamentous viruses work. At present still mainly symptomatic support. There are reports