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<B><center><font size=+1 color=blue>Bird flu threat looms</font>
<A href="http://www.engineeringnews.co.za/eng/news/breaking/?show=74182">Media's Engineering news</A>
September 19 2005
Health officials unanimously agree that a recently-evolved avian flu virus, Influenza A (H5N1), has one small genetic adjustment to make before it becomes transmissible between humans.</B></center>
In the event of this change, the virus may lead to the largest pandemic the world has seen.
While there is little we can do to prevent this, perhaps we should be asking ourselves how well South Africa and South African industry are prepared for the ramifications of a pandemic of these proportions. Avian influenza is a common highly-contagious and naturally-occurring virus among bird populations.
Of the existing subtypes, the H5N1 virus is currently the greatest cause for concern.
Although it has been in existence for some time, it has recently caused extensive epidemics in domestic bird populations and, as a result, humans are being more readily exposed to the virus.
H5N1 first infected humans through direct contact with infected birds in Hong Kong in 1997. Since then, it has resulted in a significant number of infections and deaths throughout South East Asia.
The high mortality rate can be attributed to the human population's lack of immunity to the virus. Never having been exposed to the virus before, humans are highly susceptible to infection and readily succumb to it.
Common flu viruses develop subtle variations every year. While the adaptations may cause deaths among the elderly, the infirm and very young children, human populations tend to develop some level of immunity to the virus as a result of exposure to similar viruses.
The danger lies in a completely novel virus, such as H5N1, to which no one has developed any level of immunity, resulting in high infection, mortality and morbidity rates.
Although the virus is virulent, it has not yet become transmissible between humans. Deaths to date have been the result of transmission between birds and humans and, although cases of human-to-human transmission have been suspected, these have been inconclusive.
H5N1 is a highly-adaptable virus which has recently become less virulent for birds. This implies that the virus can spread more easily with birds during migration.
Experts agree that an outbreak would pose the most serious current threat to the global community. They estimate that the H5N1 virus could cause a pandemic similar to the Spanish influenza pandemic of 1918, during which 25-million to 100-million people died worldwide.
This figure includes documented cases in the First World as well as probable Third World undocumented cases.
Influenza pandemics occur roughly every 70 years and are the result of a change in the outer coating of the influenza virus - the antigenic surface - against which white blood cells react. Each year sees an outbreak of influenza and, at the same time, a 'drift' in the antigenic layer.
Drift implies a marginal change in the virus to which we have some resistance, but which still causes infection.
Every 70 years or so witnesses a 'shift' in the antigenic layer - a complete alteration - so that our bodies have absolutely no previous experience of exposure to the virus and have no defence against it.
This may occur when a virus that normally infects other species, such as birds, pigs or horses, learns to infect humans.
Health officials propose that H5N1 may grow into a pandemic by a process of gradual mutation or it may change through a 'mixing vessel', which is a species susceptible to bird and human viruses, such as pigs.
While initial strategies involved trying to prevent the virus from getting a hold in the poultry stock in Asia by means of mass culling, it has been agreed that the virus is endemic. Mass culling is, therefore, economically untenable as well as futile.
Experts suggest that slowing down the spread of the virus to delay its repercussions may be the only solution, as it will buy time for the manufacture of an appropriate vaccine.
The possibility of a worldwide pandemic has prompted the World Health Organisation to publish new international health regulations, suggesting methods to deal with outbreaks.
Director of intensive care at Johannesburg Hospital Professor Guy Richards urges South African preparedness in the face of this global threat.
He says that the only way to inhibit the spread of the virus is by means of vaccination, a method that is not currently available to us, as one would have to be manufactured for a strain capable of human-to-human transmission.
Even the availability of an effective vaccine would not protect South Africa from H5N1,since international vaccine manufacturers, who are based in the US and Europe, would be likely to provide antivirals and vaccines to their own populations before providing countries like South Africa, which are “low on the feeding chain”, says Richards.
While South Africa does not manufacture vaccines, a feasibility study is currently under way to determine the viability of such an endeavour.
Richards says, however, that, as the study is yet to be completed, the necessary construction of a facility capable of development and manufacture of a vaccine would take too long to be of use if the virus were to cause a pandemic in the near future. The more people who are vaccinated, the greater the likelihood of preventing the virus from spreading, though little could be done for those already infected. The antiviral drug - Oseltamivir - which is still somewhat effective against the virus, is being stockpiled by world powers like the UK, the US and Japan. Manufacturers have advised stockpiling, saying that, in the midst of a pandemic, companies would be unable to supply sufficient drugs.
Richards says that South Africa has yet to register the drug with the Medicines Control Council, meaning that it cannot be imported legally into the country.
In South Africa, between 10-million and 12-million people are affected by common flu viruses every year. Richards estimates that at least this number would be infected with H5N1, although it is likely that it would affect more people, taking into account human susceptibility.
Considering the high mortality rate associated with H5N1, he suggests that the worst-case scenario for South Africa would involve the loss of between 6-million and 8-million people.
A pandemic of this magnitude has not been experienced before and we are, therefore, unprepared for the effects it may have, says Richards.
He adds: “Existing plans presuppose the existence of a healthy ground force who will be able to participate in the control process.” Richards' concern is that this significant loss of life would include the country's ground forces, such as the armed forces, the police service and, in particular, health-care workers. He suggests that, should the virus mutate and become transmissible between humans, South Africa may have to close its borders in order to protect its population against infection.
“Our hope is that the virus delays its ability to spread from human to human long enough for the world to make enough vaccine,” says Richards.
“We must remember, however, that, if it starts before the vaccine is produced in adequate amounts, South Africa will be one of the last countries to receive the vaccine.”
Richards warns that the virus is likely to affect all countries, particularly those like South Africa, which has a large international-communication system.
He cautions against panic, but stresses that we must take the situation seriously and make plans for such an eventuality in advance.
We should plan a coordinated national response in the event of a pandemic as well as source vaccine and currently-available therapies such as Oseltamivir, he adds.
South African National Institute for Communicable Diseases (NICD) director Professor Barry Schoub suggests that the conditions facilitating the transmission of the virus from birds to humans may include population dynamics as well as ecological issues.
Human-population increase has led to closer contact between humans and animals, greater quantities of domestic and commercial poultry farming, as well as more contact with wildlife. Due to agricultural expansion, farmers are coming into greater contact with aquatic birds, which are a reservoir for the development of flu viruses.
As a result, domestic birds and humans are coming into closer contact with less-known varieties of flu. It is in instances such as these that other animals, such as pigs and horses, can become a mixing vessel for the virus to become transmissible between humans.
The virus would become an international threat once it mutates to enable human-to-human transmission, which would encourage a rapid spread.
Although a vaccine is available for poultry, no human vaccine for H5N1 has yet been developed. Schoub says that developing a vaccine would not be difficult, but the problem lies in the time it would take to manufacture and distribute such a vaccine.
He adds that Oseltamivir is still relatively effective as a treatment drug, even though H5N1 has built up a small degree of resistance to it. The resistance, however, is not a significant cause for concern as yet.
H5N1 has displayed an alarmingly high mortality rate, though it has since dropped to less than 30%.
Schoub explains that the reason behind these figures is that only the most serious cases, those who have required intensive-care treatment and many of whom subsequently died, were identified.
Many other infected cases were probably not recorded.
However, the lower mortality and morbidity rate are not a reason for apathy, especially if one is to consider the influenza pandemic of 1918, which had a mortality rate of 2,5%.
Schoub emphasises the importance of preparedness in the face of a virus that could pose serious health risks. While vaccines are the best form of preparedness, they are not 100% effective and could not entirely eliminate the virus. Nevertheless, they would certainly confine its spread.
Netcare Travel Clinics medical director Dr Andrew Jamieson says that South Africa's ongoing health concerns, such as HIV/Aids and malnutrition, make the formulation of a plan to deal with H5N1 more problematic.
These significant health issues detract from the attention that should be given to the pandemic threat and, in the event of a pandemic occurring, will exacerbate the problem.
Jamieson explains that previous pandemics, such as the 1918 Spanish influenza, resulted in significant fatalities even among young adults, suggesting that, regardless of youth, strength and the immunity associated with these factors, the virus is likely to affect everyone.
It is thought that the virus will probably occur in two waves - an initial infection that spreads around the world, with a second wave during the following winter months.
Jamieson says that there is little we can do to prevent the pandemic in South Africa.
While we may be able to stockpile the antiviral agent Oseltamivir, this would be a stopgap that might be able to reach between 2% and 5% of the population. It may be used in an attempt to protect healthcare workers.
Jamieson adds that the vaccine currently being stockpiled by the UK may give some protection, but will not necessarily protect against the virus in its pandemic form.
In order to cause a pandemic, the virus will have to alter its genetic make-up slightly, and the current vaccine is only functional against the known strain of the virus.
Jamieson estimates that, in the worst-case scenario, the virus could kill between 100-million and 250-million people worldwide while, in the best-possible instance, it would cause approximately 7-million deaths.
“We are looking at a major threat to world order and stability,” says Jamieson.
H5N1 would affect most companies and, combined with South Africa's high HIV incidence in the military forces, the police service and among teachers, the results could be apocalyptic. Water and electricity services would also be under serious threat.
As part of the Netcare group, the travel clinic is involved in intelligence on infectious diseases.
Jamieson says the organisation examines how infectious diseases affect companies and is particularly involved in megaprojects and infrastructural-development projects.
Any labour-intensive industry, such as construction or mining, would be affected by an outbreak and, hence, awareness for the sake of risk management is essential.
H5N1 is considered to present a substantial risk in terms of company risk management.
“The risk of outbreak should be on the radar screen of risk-management practitioners throughout the country,” says Jamieson.
He explains that, as a healthcare organisation, risk management within the company includes maintenance of essential services within the organisation, education services for staff and hygiene education.
“There are a number of non-medical practices that could help to prevent the spreading of the virus,” says Jamieson.
The organisation is also examining the value of stockpiling antiviral agents for its own purposes as well as the most rapid possible means to obtain vaccines.
It is also examining how a pandemic will affect systems within the company, such as provident funds and medical aid.
Jamieson emphasises the importance of infrastructural issues, such as the generator capacity for hospitals where influenza cases would be nursed, what would happen if hospitals were swamped and how nursing staff would be managed in the event of a pandemic.
He says the South African government has an initial action plan, although, with the current health problems, the validity of stock-piling expensive drugs in preparation for a pandemic pales in the face of immediate health needs. Netcare is also engaged in an initiative with government and a local vaccine company to begin vaccine manufacture. Jamieson points out that, unless we have our own manufacturing facility, we will not be able to obtain vaccines timeously.
He adds that manufacturing vaccines is expensive, but that a flu-vaccine market does exist in South Africa. Ideally, we should manufacture vaccines annually, as there is a need to produce vaccines for the three flu strains that infect people during the interpandemic flu phase. Vaccine manufacture is risky and can involve batch failures.
As a result, it will require government backing or subsidy.
Nevertheless, this virus is worth the money, even as a simple national defence strategy, says Jamieson.
South Africa will look at maintaining essential services as part of its national disaster plan.
Jamieson advises that South Africa should be looking at implementing an organised plan that is as comprehensive and affordable as possible at government level.
He adds that there is reason to believe that we are moving towards this through the Department of Health and the NICD.
Within the private sector, companies should be aware of H5N1, and risk managers involved in large projects should take measures to mitigate that risk as much as possible.
Jamieson emphasises the importance of routine interpandemic flu vaccination. Although this would have no effect against a pandemic, it would assist the country to develop an infrastructure that enables more-efficient distribution of influenza vaccines, thereby building capacityto immunise the population once a suitable vaccine has been developed.
By limiting the number of people infected with common flu viruses, combinations of the avian H5N1 virus with common human viruses can be prevented, avoiding the creation of a superbug that is readily transmissible between humans. This is of greater importance in Asia, however, where direct infection from birds is more likely to happen. Vaccine producers claim that within 9 to 12 months of having the correct vaccine, about 5-billion doses could be produced, barring batch failures. It would then become an issue of distribution, says Jamieson, and it is likely that the developing world would suffer the most due to logistical costs.
He says the future of the virus is unstable and may fulfil a number of predictions. H5N1 could develop greater virulence in birds and eventually burn itself out among the bird population. Alternatively, it could develop into a mild flu, although this is unlikely, as influenza A is generally not a mild virus. It could combine with one of the common flu viruses, becoming less virulent and more transmissible, or it could continue as it is for years to come.
Considering viruses' growing ability to survive for longer periods outside the body, and the suggestions of transmission between humans, Jamieson doubts this, saying that all the pointers indicate the virus gathering momentum and developing into a pandemic.
