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The Avian Influenza virus causes uncontrollable cell replication of respiratory cells which takes over a majority of the cells machinery causing cell death.
Neuraminidase inhibitors stop the virus infecting other cells. A vaccine is available however due to low transmission rates it is currently no given to the general public.
Antiviral stockpiling is crucial to combat the epidemic a long with selective vaccination programmes.
Biosecurity farming practices will ensure the slowing down of the epidemic from the source.
Certain issues arise in dealing with the epidemic: Low raw material reserve for current antivirals, non strain specific vaccine with low protection rate and a large strain on public services in stopping a pandemic.
Epidemic and pandemic scares have been plaguing humanity since the start of time, however the study of epidemiology has only recently become well developed and in these modern times it is possible to combat an epidemic successfully and save the lives of many. The influenza pandemic of 1918-1919 killed more people than the First World War, the figure lies between 20 and 40 million people. It has been cited as the most devastating epidemic in recorded world history . The Avian Influenza virus has the potential to claim numerous lives in the right conditions. This report indentifies how to deal with a possible epidemic and the issues faced in doing so.
In conducting my research for this report I have used a large variety of resources. The information I was seeking was the disease framework of the Avian Influenza virus and information on how previous epidemics have been dealt with.
Initially my search began by using popular search engines such as Google, this was fruitful and I obtained a few medical articles however it was becoming very time intensive to sift through websites finding appropriate material. At this point I decided to use journal databases so that I would not have to waste time identifying material which was both reliable and relative. Pubmed was one of the main resources I used, search terms such as 'Avian Influenza' and 'Avian Influenza epidemic' returned positive results. Other journals I found came from the BMJ database and the Wiley Online Library which I was able to access through my Athens account.
What is Avian Influenza?
A virus is made up of a package of genetic material bounded by a protein and lipid shell. There are three types of Human influenza - A, B and C. Type A is the most virulent and pathogenic (highest mutation rate). The type A influenza virus consists of 10 proteins and eight strands of ribonucleic acid, which carry the code for making the proteins. The lipid shell of the virus contains proteins that are able to bind to receptors located in the respiratory tract and lungs of the victim. Virus replication takes over so much of the cell's machinery that the cell dies these dead cells in the airways result in a runny nose, scratchy throat and a very large number of dead cells in the lungs may result in death.
How do medicines and vaccines combat Avian Influenza?
Two antiviral medications oseltamivir and zanamivir treat influenza caused by the H5N1 virus. Neuraminidase (N) inhibitors such as oseltamivir block the release of the newly formed virions from the infected cells. This stops the newly formed virus spreading to other cells. Due to high rates of mutation and multiple strains of influenza some strains have appeared to be resistant to Oseltamivir. The clinical efficacy is currently unknown against H5N1.
A vaccine has been developed to protect humans against the avian influenza virus however due to the low transmission rate of avian influenza it is has not been used by the general public. The vaccine contains an antigen with an adjuvant (a chemical that stimulates the immune system) in order to prepare the immune system for the virus by storing antibodies to destroy the virus in a future infection.
Spread of the virus:
Most cases of avian influenza infection in humans have resulted from contact with infected poultry or surfaces contaminated with secretion/excretions from infected birds. The spread of avian influenza viruses from one ill person to another has been reported very rarely, and has been limited.
An epidemic is the rapid spread of a contagious illness of which the number of new cases will rise exponentially. The total number of cases will double every few days and in the case of a pandemic this spreads across the entire globe affecting all continents rather than one area.
History of Avian influenza epidemic:
Outbreaks of avian influenza occurred among poultry in eight countries in Asia during late 2003. Over 100 million birds in the affected countries either died from the disease or were killed in order to try to control the outbreaks. In March 2004, the outbreak was under control. June 2004, new outbreaks of influenza H5N1 among poultry and wild birds were reported in Asia. Since that time, the virus has spread geographically. Human cases of influenza A (H5N1) infection have been reported mainly in Asia and Africa. There have been 282 cases of confirmed mortality and 467 cases of morbidity caused by the virus. Vii
Preparation for epidemic:
The backbone of the plan to combat an epidemic will rely on the stockpiling of antiviral drugs which will be necessary in order to reduce the strain on pharmaceutical companies to mass produce drugs during the emerging epidemic. 'Depending upon the virulence of the emerging virus, a lack of pre-existing immunity can lead to overwhelming morbidity and deaths ranging in the millions.' This means that vaccines should be issued to government officials and healthcare workers in order to maintain bureaucracy and health services. Funding of the development of new antiviral drugs and a strain specific vaccine will be crucial in order to target the correct form of Influenza as the seasonal Influenza has shown new resistance against Amantadine and Oseltamivir due to mutation. The epidemic will have several phases such as, no human-human transmission and low human-human transmission and the strategy to combat each phase will have to be different. Surgical masks should be issued to all members of public and especially those who deal with large numbers of people and thus have a large chance of coming into contact with people who have contracted the virus. vi
All health care professionals are at risk of being in contact with patients with the H5N1 virus, thus should be vaccinated and take precautions such as wearing surgical masks and gloves along with practicing strict hygiene such as washing their hands thoroughly after patient contact.
The general populous will have to be educated via the media on the correct practices in order to minimise chances of contracting the virus this will be the key to successfully dealing with the epidemic. Information has to be available from a range of avenues; information hotlines and websites should be set up to inform the public and keep them updated on the latest news and advancements of the epidemic.
Instructions on how to handle raw poultry and eggs will be crucial to combat virus transmission:
Wash hands with soap and warm water after contact with raw poultry and eggs.
Thoroughly wash cutting boards and utensils with soap and hot water.
Cook poultry to a temperature of at least 73 degrees C.
Cook eggs until firm.
Biosecurity practices should be employed by poultry farmers:
Farmers disinfect their clothing and shoes as well as their farm equipment.
They should separate domestic birds and wild birds.
Infected birds should be quarantined and culled.
How to stop an epidemic becoming a pandemic:
The change of an epidemic into a pandemic relies on the spread of the influenza virus from one geographical area to the next. In order to stop or at least minimise this it will be necessary to have strict travelling restrictions and precautions. Travel warnings which involve informing the public to not travel to epidemic affected countries and what the consequences of not obeying such instructions would be. These warnings have a good chance of reducing the numbers of individuals who will contract the virus and then return to their home country.
Travel restrictions may help to decrease the spread of the epidemic, however this will be very difficult to implement. The number of both departing and arriving persons could be capped. 'Modelling evidence indicates that restrictions need to be almost complete to significantly delay the arrival of influenza.'
Travel restrictions still permit the return of citizens, or it can be used to specifically focus on capping or denying the entry of travellers from countries where human-to-human transmission of influenza has been established. Arriving persons should be screened in order to identify those individuals which may be infected, this procedure should be carried out for all those returning or arriving from areas where there is an epidemic present. In order to successfully carry out entry screening it will be necessary to have facilities for medical examinations and quarantine available at all major airports and travel hubs. Viii
Issues faced in dealing with the epidemic:
Antiviral drugs have the ability to provide both prevention (chemoprophylaxis) and treatment of the Influenza if administered within 48 hours of the onset of symptoms. Antivirals are a useful combination with vaccines in order to relieve the strain on the health service and lower the economic burden of an influenza epidemic. Neuraminidase inhibitors are however costly due to the lack of raw material. They do however have very few adverse effects, low evidence of drug resistance, and therapeutic value in decreasing lower respiratory tract complications, making them an ideal solution. Research proves that treatment with neuraminidase inhibitors reduces virus shedding; impact on transmission needs further investigated.
Vaccines can be stored before the epidemic reaches the UK, however these vaccines will not be well matched to the specific strain causing the epidemic. Research shows that mismatched vaccines may provide up to 30% defence against the virus and lower transmission rates by up to 50%.
A vaccine designed to target the exact strain of the virus provides around 70% protection and can reduce transmission by 80%. This data shows that if the entire population was vaccinated against the virus even with a mismatched vaccine the already low transmission rates would be lowered significantly decreasing the likelihood of the onset of a pandemic.
In the current economic crisis the UK is an unfavourable location for pharmaceutical company investment and many firms look to set up production capacities in countries where labour is cheap and raw material are available.
The Avian Influenza virus can potentially be a very large threat to all nations. My report identifies the need for a comprehensive plan in the event of an epidemic and how to stop it becoming a pandemic. There are several issues which have to be addressed in dealing with the threat; all services ranging from the national health services and border control have to contribute. There are two main principles to alleviating an outbreak, the infected populous has to be isolated and treated effectively and the healthy individuals must be educated in practices to avoid becoming infected.