Ebola virus, what to do in the event of an Ebola outbreak?

on 17.6.09 with 0 comments

          1. Recognition

The very first step is to recognise possible clinical cases. Steps should be taken to identify and type the virus (send a blood sample safely to a well-equipped laboratory). In a laboratory which is protected and equipped to work with dangerous pathogens (so-called biosafety level 4), an attempt will be made to detect viral antigen, antibodies and viral RNA (reverse transcriptase PCR) and carry out an analysis of the genome in order to establish which Ebola subtype is involved.

          1. Central organisation

If it is established that it really is Ebola, the government will be notified. Central control, registration and coordination is essential for combating an epidemic. Groups specifically responsible for a certain part of the campaign will be set up: clinical care, surveillance in the community, logistics, collecting the dead and safe burials, investigating rumours, informing the population, epidemiological study, research, reception centre, etc. These days it is also useful to appoint someone who can handle the press correctly. Every day information will be exchanged between the various teams and the latest developments will be reported to the WHO in Geneva.

          1. Isolating patients

The patients' movements should be limited. They should be isolated (no direct physical contact with patients, blood, excreta etc.). New patients must be directed to an emergency unit. Here, based on the history (contact with Ebola patients, fever, haemorrhagic symptoms) and a physical examination (melena, red eyes, haemorrhages), new patients must be divided into Ebola patients, non-Ebola patients and cases where there is doubt. Ebola cases must be kept in isolation. Cases where there is doubt should be kept elsewhere for observation (also in isolation). Often contact with Ebola will not be reported due to superstition, fear of stigmatization or if there was sexual contact with a person who subsequently developed Ebola infection. The absence of a rapid antigen detection test on-site can be a practical problem for the clinicians working in the field.

          1. Barrier nursing

Personal protection (masks, goggles, aprons, boots, disinfection supplies) for medical staff and for people who care for the sick person (often family) is necessary. Demonstration of how to use the protective equipment and proper explanation are imperative. Equipment should be disinfected rigorously with, for example, bleach (hypochlorite solution). Objects, which cannot be sterilised, must be burnt under supervision. People who are suspected of being infected with the Ebola virus should be cared for by people who understand and use personal protection. Basic needs (drink, food, pain-relief, hygiene, etc.) have to be met. In emerging situations, when the medical staff is overwhelmed, only one member of the family should be allowed into the patient's room, and then only after thorough instructions and regular supervision.

          1. Ebola Treatment

Since there are no known active antivirals against Ebola virus, treatment will be symptomatic. In all epidemics so far, treatment was done in very basic circumstances and treatment in an intensive care unit was not possible. During epidemics, good nursing care might lower the mortality. Good hydration and nutrition is essential. High calory liquid food is easier to swallow that solid food, due to severe pain in the throat. Complications and other infections will be treated, e.g. metoclopramide (Primperan) or domperidon (Motilium) against vomiting, loperamide against diarrhoea, ranitidine against gastric bleeding. Paracetamol, ampicillin and quinine or another antimalarial will be given if bacterial surinfection and/or malaria are suspected. Chlorpromazine and even haloperidol might be considered in case of agitated confusion. Vomitus, sputum, faeces and urine will be collected in a plastic bucket and mixed with strong bleach before disposal. Aspirin is to be avoided. Rehydratation is important.

          1. Surveillance

People who have recently had contact with Ebola patients but do not display symptoms have to be placed under supervision (surveillance) or in quarantine for 3 weeks. If this does not take place in a hospital, but at home, daily (radio) contact is desirable.

          1. Convalescent patients

People who have survived Ebola have to remain in quarantine for a further 3 weeks after recovery. It is not known how long the virus continues to be excreted. Sexual transmission is possible up to 7 weeks after clinical recovery. Convalescent serum can be stored if necessary, but its use is controversial. Animal studies have been unable to prove any benefit of hyperimmune serum.

          1. Information

A general large-scale information campaign with adequate and practical information for the population should be started. If this results in many questions and tips, a permanent centre can be set up where information about possible new cases can be examined. In view of the extreme virulence, the incomplete knowledge about these pathogens and memories of the impact of the earlier plague and yellow fever epidemics, these pathogens can capture the imagination of the general public. Superstition and belief in witchcraft can lead to misunderstandings and violence.

          1. Nosocomial transmission

Centres with a poor medical infrastructure and with a high risk of nosocomial transmission, have to be closed down temporarily. This applies both to large hospitals and small one-person clinics with only a few needles and syringes. Strict guidelines have to be issued to centres which continue functioning, particularly as regards disinfection, the use of needles and syringes, vaccinations and surgical procedures. In many places non-qualified private individuals have only a few (non-sterile) needles and syringes, which they use for all kinds of injections.

          1. Burials

The deceased should not be washed and the bodies have to be isolated and buried as quickly as possible and reasonable. This sometimes causes problems with the family and acquaintances of the deceased because of the disruption of traditional rituals. The government has a role to play here in law enforcement. It is also useful to have an idea of the average mortality in an area prior to the Ebola outbreak.

          1. Social impact

Caring for orphans in the community should be organised if this does not take place through the traditional system of the extended family. The latter sometimes does not work because of fear, prejudice and practical problems.

          1. Logistics

Logistics play a very important role and include, among other things, equipment and materials, administrative support, accommodation, money and wages, communication, transport, fuel, safety and stock management. Good management is essential and has to be entrusted to reliable people. The NGO Médecins Sans Frontières has a lot of experience in handling the logistics of such operations.

          1. Personnel

Experts in various areas cannot, in most cases, make themselves available quickly for a long time and a rotation system should be organized. It is best if staff do not change too frequently in order to achieve a minimal continuity locally. Realistic guidelines for cases in which medical personnel are infected accidentally have to be drawn up.

          1. Epidemiology

Epidemiological research should attempt to identify transmission routes and secondary cases. One of the first questions which has to be answered is whether the course of the epidemic suggests aerogenic transmission or not. Risk factors for infection should be identified. An attempt will also be made to trace the first case in order to understand how the chain of infection started. However, this person may well have died. Several people, such as customers, work colleagues, neighbours, family and friends may be able to provide useful information. A reminder of the terminology: the index case is the patient in whom the disease first indicated the existence of an outbreak. The index patient always remains the same person irrespective of whether earlier cases are discovered later. The very first case is called the primary case, not the index case. Later secondary, tertiary, etc. cases can follow.

          1. Reservoir

Because an animal reservoir is assumed, extensive attempts have been and are being made to identify this. An “ecological” team should be exclusively involved in this and will study different animals in the vicinity. An investigation should also be carried out into whether the virus is “exported” from the isolation units in the hospital to the environment. In addition to the fieldwork itself, there then follows the tedious analysis of the various potential hosts (both for the presence of the virus and their taxonomic identification). If new, more powerful and sensitive test methods are developed, samples from earlier field expeditions can, if necessary, be reexamined. A detailed description of the ecological/botanical environment in which the primary case emerged could be useful. As cases occurred in the Tai National Park in Côte d’Ivoire, where an ethological study of chimpanzees had been going on for years, this became a starting point for research. To date the analysis of the numerous arthropods and vertebrates has not produced a single positive viral isolate, but antibodies against Ebola virus have been found in fructivorous bats. It was discovered that the Ebola glycoproteins which make up the "shell" of the virus are chemically and structurally very similar to those found in several bird retroviruses. This suggests that birds might be implicated in the transmission of illness. At this moment, this is still hypothetical.

          1. Laboratory

Rapid sample analysis (blood samples of patients, skin biopsies, etc.) and rapid transmission of the results is recommended. Logistical problems can hinder this. Investment in research and cooperation will pay dividends.

          1. Looking for isolated cases

The maximum known incubation period is 21 days. After the end of the epidemic (no more cases for a minimum of 6 weeks), surveillance can be carried out locally. It is extremely likely that isolated cases and limited outbreaks will occur regularly. In order to obtain a better understanding of this disease, long-term surveillance is necessary. This can be done by analysing skin biopsies (immunohistochemistry) from deceased people who had suggestive symptoms before death. These biopsies could be performed and collected by locally trained doctors. The technique has the great advantages of being simple and having high sensitivity. No cold chain is necessary and transportation can take place safely. The sample is kept in a bottle of formalin. This kills the virus. The bottle is then immersed in a bleach solution in order to disinfect the exterior. The same technique is under evaluation for future monitoring of other haemorrhagic diseases with fever (e.g. yellow fever).

          1. Future prevention

We do not know how all epidemics started, but several followed the consumption of infected apes. The risk of nosocomial transmission is clear. A safe medical infrastructure has to be built for the future. This is easier said than done. Naturally this does not only apply to Ebola, but to the whole spectrum of medicine. The cases of Ebola fever in South Africa and Switzerland show that the virus can emerge anywhere in the world, owing to modern rapid means of transportation.

          1. Vaccine

At the end of 2000, the first favourable results of an experimental vaccine were reported in which cynomolgus monkeys (Macaca fascicularis) were protected against a fatal dose of Ebola virus, the Mayinga strain. An immunisation technique was used which was based on viral DNA injection followed by multiple boosters with a modified adenoviral vector. However, the vaccination regime took several months to produce immunity. In August 2003, Gary Nabel of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland announced the results of a new trial. Cynomolgus monkeys were protected 28 days after a single injection of a modified adenovirus in which parts of the Ebola genome coding for nucleoprotein and glycoprotein were inserted. How long the protection lasts is not known at present and it is also not known if there is protection against other Ebola subtypes. If similar promising results with a one-shot vaccine would be obtained in humans, fast ring vaccination would become possible in case of a new outbreak. Adenoviruses are common human pathogens (e.g. common cold) and many people have anti-adenoviral antibodies in their blood. If this will interfere with this vaccination technique is not yet known. The use of alternative adenoviral serotypes might be useful if this would prove to be the case. Another vaccine is based on a modified animal pathogen, the vesicular stomatitis virus. When VSV's glycoprotein-gene was replaced by that of Ebola, the resulting virus protected animals against lethal Ebola challenge. However, VSV can occasionally provoke disease in humans, so there is some uncertainty about the safety of such an approach.

Category: Medical Subject Notes , Medicine Notes



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