October 2006

Pandemic Avian (Bird) Influenza

By Terrance Malkinson

In May, the Bush Administration released the 233-page U.S. National Strategy for Pandemic Influenza Implementation Plan [www.whitehouse.gov/homeland/nspi_implementation.pdf]. As described by President Bush, the plan "ensures that our efforts and resources will be brought to bear in a coordinated manner against this threat. The plan describes more than 300 critical actions, many of which have already been initiated, to address the threat of pandemic influenza."

Although the outbreak or timing of a pandemic is in no way certain, it is important that an effective plan be created and that citizens are familiar with it, so that the nation will be prepared and united in action in the event that this pandemic or other epidemic should emerge.

What is a Pandemic?

A global flu pandemic occurs when a new influenza virus emerges for which the world's population has little or no immunity. A severe influenza pandemic could lead to high levels of illness, death, social disruption and economic loss. Large numbers of people in many places around the globe would become seriously ill at the same time. In the event of a pandemic, public health measures may be imposed to help contain or limit the spread of infection.

The 20th century has seen three influenza pandemics. The 1918 influenza pandemic caused about 500,000 U.S. deaths and up to 40 million worldwide. The 1957 influenza pandemic caused about 70,000 U.S. deaths and 1-2 million worldwide. The 1968 influenza pandemic caused about 34,000 U.S. deaths and 700,000 worldwide.

It is difficult to predict when the next influenza pandemic will occur, or how severe it will be. The current concern is avian (bird) Influenza of the H5N1 subtype. Many uncertainties are associated with this particular strain. After all, avian influenza is a disease of birds not humans. Many scientists believe that it will be difficult for avian flu virus to mutate into a form that is transmissible to and among humans.

To keep things in perspective, it is important to note that other diseases and conditions are responsible for large numbers of human deaths every year. For example, 800,000 people will die this year from measles, and 600,000 children will die from rotavirus. An estimated 2 million babies die globally within their first 24 hours annually. Stroke kills nearly 157,000 people a year. As of 27 April 2006, only 205 confirmed cases of avian flu in humans have been reported, and 113 deaths since 2003. Regardless, it is prudent to become informed.

Death rates are determined by the number of people who become infected, the virulence of the virus, the characteristics and vulnerability of affected populations, and the availability and effectiveness of preventive measures. Education is important for preparing for a pandemic, helping us to make informed individual and societal decisions. Medical scientists and public health officials throughout the world have been working diligently to strengthen systems to detect outbreaks of influenza that might cause a pandemic.

Should a pandemic occur, it will have a considerable global impact. Planning and preparation information and checklists are being prepared for various sectors of society, including information for businesses, individuals and caregivers. Links to information on how to develop a plan is included at the end of this article.

How Does Seasonal Flu Differ From Pandemic Flu?

Pandemic influenza is different from seasonal flu, which for most people is an unpleasant illness, but typically runs a self-limiting, non-life-endangering course.

Seasonal Flu

Outbreaks follow predictable seasonal patterns; often in winter. Immunity is often built up from previous exposure. Healthy adults are usually not at risk for serious complications. The very young, the elderly and those with underlying health conditions are at increased risk for complications. Health systems can usually meet needs. Vaccines developed based on known flu strains and are available, as are supplies of antivirals. Symptoms include fever, cough, runny nose, muscle pain. Generally causes a modest, manageable impact on society.

Pandemic Flu

Occurs rarely. No previous exposure; population possesses little or no immunity. Healthy people may be at increased risk for serious complications. Health care systems may be overwhelmed. Vaccine would not be available in the early stages of a pandemic. Effective antivirals may be in limited supply. Number of deaths could be quite high. Symptoms are more severe and complications frequent. May cause a major impact on society with the potential for a severe impact on domestic and world economies.

The Virus

New influenza viruses emerge as a result of a process called antigenic shift, which causes a sudden and major change in the virus. Proteins on the virus' surface combine in new ways as a result of mutation or exchange of genetic material with other influenza viruses. These changes result in a new influenza virus subtype, resulting in an influenza pandemic.

Avian (bird) flu is caused by influenza A viruses that occur naturally among birds. There are different subtypes of these viruses because of changes in certain proteins on the surface of the influenza A virus and the way the proteins combine. Each combination represents a different subtype. All known subtypes of influenza A viruses can be found in birds. The avian flu currently of concern is H5N1. The issue is that H5N1 will evolve into a virus capable of human-to-human transmission. Scientists cannot predict for certain whether an avian influenza (H5N1) virus will cause a pandemic.

The H5N1 avian virus is raising concerns about a potential human pandemic because:

• It is highly virulent

• It can be spread by migratory birds

• It can be transmitted from birds to mammals and perhaps to humans

• It continues to evolve

• Wild birds have been infected, becoming carriers showing no symptoms

Human influenza virus refers to those subtypes of avian influenza that spread widely among humans. Influenza A viruses are constantly changing, and strains might adapt over time to infect and spread among humans. These viruses do not usually infect humans. H5N1 is one of the few avian influenza viruses to have crossed the species barrier to infect some humans. It is the most deadly of those that have crossed the barrier.

The spread of H5N1 virus from person to person has been limited and has not continued beyond one person. In Asia, Europe and Africa, more than half of those infected with the H5N1 virus have died. Most cases have occurred in previously healthy children and young adults. Because all influenza viruses have the ability to change, scientists are concerned that H5N1 virus may in the future change to a form capable of spreading quickly among people.

Vaccination and Treatment for H5N1 Virus in Humans

There is no available vaccine available to protect humans against the H5N1 virus that has been contracted in Asia, Europe and Africa. The U.S. Department of Health and Human Services (HHS) is addressing the problem in a number of ways. These include the development of pre-pandemic vaccines based on current lethal strains of H5N1.

Influenza vaccines are designed to protect against a specific virus, so a pandemic vaccine cannot be produced until a new pandemic influenza virus emerges and is identified. It would take at least six months to develop, test and produce a vaccine. The influenza vaccine production process is complex, and is complicated by the fact that influenza virus strains continually evolve. Research is underway to make vaccines more quickly.

In the event of an outbreak, the government will need to work closely with manufacturers and distributors. Fairness in vaccine distribution and use during a pandemic is important. Protecting people at high risk, and maintaining essential day-to-day services will be important considerations.

Antivirals are drugs that may be given to help prevent viral infections or to treat people who have been infected by a virus. Antivirals may help prevent infection in people at risk and lessen the impact of symptoms in those infected with influenza. It is unlikely that they would substantially modify the course or effectively contain the spread of an influenza pandemic. The H5N1 virus that has caused human illness and death in Asia is resistant to amantadine and rimantadine, two antiviral medications commonly used for influenza.

What would be the Impact of a Pandemic?

In the event of an avian influenza pandemic, a large percentage of the global population would require some form of medical care. Health care facilities could be overwhelmed, creating a shortage of hospital staff, beds and other supplies. Capacity at non-traditional sites, such as schools, would need to be increased to cope with demand. The need for vaccine would likely outstrip supply, and the supply of antiviral drugs would also likely be inadequate early in a pandemic. Difficult decisions would need to be made regarding who gets priority on antiviral drugs and vaccines.

Travel bans, school and business closures, and cancellations of events could have major impact on communities and citizens. Many people could become sick at the same time and would be unable to go to work. Many would stay at home to care for sick family members. Schools and businesses might close to try to prevent spread of the disease. Large group gatherings might be cancelled. Public transportation might be scarce.

What Is The Government Doing Now To Prepare For A Pandemic Flu Outbreak?

Many agencies globally are making plans to prepare for, respond to, and contain an outbreak of pandemic flu. These activities include:

• Supporting local health agencies' efforts to prepare for and respond to a pandemic flu outbreak.

• Working with the World Health Organization and other organizations to help detect and contain outbreaks.

• Building a stockpile of antiviral drugs to help treat and control the spread of disease.

• Supporting the manufacture and testing of possible vaccines, including finding more reliable and quicker ways to make large quantities of vaccines.

• Working with other agencies to prepare and to encourage communities, businesses, and organizations to plan for a pandemic influenza outbreak.

Why Is This Information Important To You?

It is important for everyone to be knowledgeable about the risks associated with an influenza pandemic and to prepare adequately for an event that would have significant social and economic costs. The following excerpt is taken from a  December 2005 letter sent to U.S. business leaders[ http://www.pandemicflu.gov/plan/panbusletter.html]:

In order to ensure maximum preparedness, your business should develop specific plans for the ways that you would protect your employees and maintain operations during a pandemic. Companies that provide critical infrastructure services, such as power and telecommunications, also have a special responsibility to plan for continued operation in a crisis and should plan accordingly. As with any catastrophe, having a contingency plan is essential.

— Michael Chertoff, Secretary of Homeland Security; Michael O. Leavitt, Secretary of Health and Human Services; Carlos M. Gutierrez, Secretary of Commerce.

The HHS and the Centers for Disease Control and Prevention have developed a checklist that identifies important, specific activities large businesses can do now to prepare [http://www.pandemicflu.gov/plan/businesschecklist.html] categorized as:

• Planning for the impact of a pandemic on your business

• Planning for the impact of a pandemic on your employees and customers

• Establishing policies to be implemented during a pandemic

• Allocating resources to protect your employees and customers during a pandemic

• Communicate to and educate your employees

• Coordinating with external organizations and help your community

A Web site managed by the HHS [www.pandemicFlu.gov] provides a one-stop point of access to current and historical information on avian and pandemic flu information. Another is the World Health Organization [http://www.who.int/en/]. The Occupational Health Disaster Expert Network Pandemic Influenza Information Site for Workplace and Workforce Planning provides information on worker and public health issues [http://ohden.sph.unc.edu:9002/pandemic/]. Many local government and health agencies also have information available for you on bird flu.

Terrance Malkinson is a proposal manager/documentation specialist; an elected Senator of the University of Calgary; a Governor of the Engineering Management Society; international correspondent for IEEE-USA Today's Engineer Online; editor-in-chief of IEEE-USA Today's Engineer Digest; editor of IEEE Engineering Management; and associate editor of IEEE Canadian Review. The author is grateful to the Haskayne School of Business Library at the University of Calgary. He can be reached at malkinst@telus.net. Comments may be submitted to todaysengineer@ieee.org.