H5N1 Avian Influenza: Is America Prepared for a Pandemic?

Introduction and Problem Overview

"The effects of a bird flu pandemic would dwarf even the devastation caused by Hurricane Katrina." — Marty Evans, Chairwoman of the Red Cross, 2005

Innovations in telecommunications and transportation over the past century have made the world a much smaller place; what happens in other countries can have an enormous impact on the United States today. The events of September 11, 2001 made it absolutely clear that Americans are not immune from attack on the home front, and many observers have grown increasingly concerned about the potential threat represented by biological, chemical, and nuclear weapons as well. In this environment, any virulent pathogen represents a threat to the nation's health and well-being, and H5N1 — otherwise known as avian influenza — appears to represent just such a threat. A report from Fabian (2006) suggests that if such an epidemic were to affect the United States, virtually everyone in the country would experience the loss of at least one person in their lives.

The potential threat to U.S. citizens began with events in China and Southeast Asia, where migratory waterfowl picked up the H5N1 flu virus from lake waters visited during their migration journeys (Fabian, 2006). As a result of aggressive economic development in these regions, many of the natural wetlands these birds visit have been eliminated; consequently, the waterfowl have turned to farm areas for water and food. In these concentrated regions, wild birds ultimately come into contact with local poultry, and the close interactions between waterfowl and poultry have caused the virus to spread from migratory birds into poultry flocks, resulting in numerous outbreaks of bird flu in poultry populations (Fabian, 2006). To date, more than 135 humans are known to have contracted the disease, almost always from chicken blood or droppings (Fabian, 2006).

The extent of the problem continues to elude many observers who question the threat represented by the number of dead birds — approximately 150 million thus far — compared to the relatively small number of people (about 70) who have died from the virus (Fabian, 2006). In reality, the potential threat is very real and continues to grow. Should the H5N1 virus mutate and become communicable between humans, the potential for a worldwide outbreak would become even greater. This is not the first such pandemic threat in recent years; during the 20th century, there were three such outbreaks:

1. 1918–1919 — the Spanish flu
2. 1957–1958 — the Asian flu
3. 1968–1969 — the Hong Kong flu

The World Health Organization (WHO) defines a pandemic as the confluence of three events: (1) there must develop a novel virus that the world has never seen before, to which humanity has absolutely no immunity; (2) that virus must demonstrate an ability to sicken or kill people; and (3) the virus must become transmissible among humans. According to Fabian (2006), "The first two of these conditions have now been met. It is therefore little wonder that the public health community is alarmed" (p. 47).

Complex problems require complex solutions, and the knowledge needed to address the potential health threat represented by the H5N1 virus must be drawn from multiple viewpoints across various disciplines in order to fully understand the scope of this issue (Repko, 2005). The disciplines used for analysis of the country's current readiness for an H5N1 epidemic in this study are biology, psychology, and economics.

From a biological perspective, the focus is on how the pathogen operates at the molecular level to determine its potential for mutation and the biological impact of a potential pandemic. From a psychological perspective, a primordial dread characterizes most people's views about potential biological threats because of the unknowns involved; most Americans have become accustomed to thinking that prior inoculations have made them virtually immune to any such biological agent, and the psychological impact of an avian flu epidemic could reasonably be expected to be pronounced and long-lasting. From an economic perspective, perhaps the best way to mobilize scarce resources in advance of a potential threat is to emphasize how much money is at stake; in the case of a potential H5N1 outbreak, the economic consequences would be enormous, and it simply makes good business sense to plan ahead for a worst-case scenario.

To address these issues, a critical review of the relevant peer-reviewed literature was deemed the best approach. The purpose of this paper is to create awareness among the general American population and to inform people of the potential threat represented by H5N1 without resorting to alarmist rhetoric or unfounded claims.

Background and History of Avian Influenza

It is clear from the events following Hurricane Katrina that the nation's ability to adequately respond to widespread threats to public welfare remains a work in progress. In spite of billions of dollars spent on homeland security initiatives following September 11, 2001, there are glaring gaps in readiness. These issues may come back to haunt the United States if some observers are correct about the potential threat represented by the H5N1 virus.

The general history of the problem began in 2003, when an epidemic of a viral respiratory disease called bird flu (avian influenza) first began to devastate poultry farms in many Asian countries. By the end of 2004, the virus had infected poultry in Cambodia, China, Indonesia, Japan, Kazakhstan, Laos, Malaysia, Mongolia, North Korea, Romania, Russia, South Korea, Thailand, Turkey, Ukraine, and Vietnam (Ford, 2006). Millions of birds have been destroyed by the disease or slaughtered by authorities attempting to restrict the spread of the virus (Ford, 2006).

The deadly disease known as bird flu or avian influenza is caused by the H5N1 strain of type A influenza virus. The H5N1 strain was first isolated from terns in South Africa in 1961 and is now regarded as common in waterfowl such as wild ducks; unfortunately, these wild fowl subsequently infect domesticated birds such as chickens, and the disease is virulent among this population (Ford, 2006). According to Ford, "The H5N1 virus was first found to have the capability of infecting humans in 1997, when an outbreak of bird flu in Hong Kong poultry caused severe illness in 18 persons, 6 of whom died" (2006, p. 17).

The notion of an influenza strain being transmitted from birds to humans is disturbing to many people; however, this is an age-old problem for mankind. Genetic research suggests that, in fact, all flu strains have originated from birds (Fabian, 2006). By the end of 2005, the epidemic of avian influenza had resulted in human cases of the disease in Cambodia, China, Indonesia, Thailand, Turkey, and Vietnam. Vietnam was the worst hit, with 93 cases, of which 42 died. Citing statistics from the World Health Organization, Ford reports that the total number of cases by the end of 2005 was more than 140, with approximately half resulting in death (2006).

Although sustained communicability of the H5N1 virus from person to person had not been observed, health officials remain cognizant that H5N1 has the potential to mutate rapidly, or even combine genetically with a human influenza virus to yield a virulent new strain that could easily spread throughout the global human population (Ford, 2006). In the event of such an epidemic, public health departments would be pressed to maintain their services even when employees are ill, normal supply chains are disrupted, and the nation's infrastructure is inoperative; furthermore, the traditional roles of environmental health professionals can be expected to change dramatically during a period of pandemic influenza (Fabian, 2006).

As the U.S. Secretary of Health and Human Services has noted, states and local jurisdictions will be in the vanguard of a battle that has 5,000 fronts: "A lot is going to be expected of us. Fortunately, a great deal of the preparation activities laid out below have already become part of our awareness and skill set as a result of some of the terrorism and emergency response planning that public health has recently experienced" (Fabian, 2006, p. 47).

In sharp contrast to the secretary's assertions concerning the country's level of preparedness, many experts warn that more needs to be done before it is too late. Many public health officials could become involved in administering medications and caring for the sick given anticipated shortages of healthcare workers and the potential need for warehouse hospitals; communities also need to consider ways to sustain and care for the healthcare workforce (Fabian, 2006). Employees of local health departments could easily become involved in providing assistance on this front. Additionally, some communities have many households in which children are cared for by a single parent or elderly relatives; monitoring of these households would be necessary to ensure children are still cared for should a provider become ill or die.

Therefore, the following issues remain unresolved: (1) techniques for securing food, water, and supplies to quarantined populations need to be figured out and implemented; (2) public education campaigns need to be developed to educate the public on everything from cough etiquette to alcohol hand wipes to limiting hand-to-face contact; (3) environmental health professionals will need to become involved in pandemic flu planning; and (4) there will be a critical need for reliable communications so that public health authorities can keep the public informed and help maintain community order and confidence in the government (Fabian, 2006).

It is also critical that public utilities — particularly power and water utilities — receive the assistance they require to maintain safe workplaces and to have redundant systems in place (Fabian, 2006). According to Fabian, "It is not too early to be looking at how outdated quarantine laws and protocols can be revised. Health departments will likely be involved in determining when to close schools and when public gatherings, social events, or both will need to be cancelled" (2006, p. 47).

The Secretary of Health and Human Services was direct about the urgency: "We're looking at a minimum of three to five years before we get to where we need to be. The President's plan calls for the ability to produce 600 million doses of a vaccine by 2013 — seven long years from now." He added, "If this thing ever breaks loose, I am convinced that we will need every preparation, every resource, and every body that we have to manage it in a way that minimizes its impact. It would be an irresponsible and unforgivable dereliction of our professional duty to delay our preparations until a pandemic is actually under way" (quoted in Fabian, 2006, p. 47).

Research to date indicates that two popular antiviral drugs — amantadine (Symmetrel) and rimantadine (Flumadine) — are not effective against H5N1; however, researchers have identified two others, oseltamivir (Tamiflu) and zanamivir (Relenza), that might be effective, though more research is required (Ford, 2006). The National Institute of Allergy and Infectious Diseases sponsored the production and clinical testing of an investigational vaccine based on the H5N1 virus, and in August 2005 announced that preliminary testing had been successful (Ford, 2006). Nevertheless, even after becoming available, the vaccine would still require significant time to produce, and a vaccine made for the H5N1 subtype might not provide immunity to a mutated strain (Ford, 2006).

According to an epidemiologist at the Harvard School of Public Health, there has been a dearth of preparation for an H5N1 pandemic around the world, and if such a pandemic affected the United States, the country would be able to manufacture enough vaccine for only about 25 percent of its population and enough Tamiflu for less than one percent (Ford, 2006). In response, President George W. Bush outlined a $7.1 billion plan to provide funding for the early detection and containment of any pandemic flu outbreaks both in the United States and abroad in 2005, including improved methods for creating flu vaccines and the stockpiling of antiviral drugs (Ford, 2006).

Biological Perspective on H5N1

There appears to be a more pronounced sense of urgency throughout Southeast Asia compared to the United States; in some Asian countries, taxis have installed signs warning passengers who feel ill to go straight to a hospital (Ford, 2006). The influenza pandemics of 1957 and 1968 killed millions of people each, and the great influenza pandemic of 1918 was responsible for the deaths of tens of millions; clearly, another influenza pandemic is a possibility, and preparing for the threat is a serious and difficult problem (Ford, 2006).

There are profound biological issues involved in planning for a potential pandemic of avian influenza that will adversely affect the ability of public health officials to respond. In his essay "The Growing Challenge of Avian Influenza," Imperato (2005) reports that avian influenza viruses typically infect a specific range of bird species. Subtypes of influenza A, the various strains of these avian viruses can be classified as either highly pathogenic or as of low pathogenicity, based on their genetic features and the severity of illness they cause in birds. According to Imperato:

"There are currently 27 potential forms of the three subtypes of avian influenza viruses differentiated by variations in the neuraminidase surface antigen. Thus, H5, H7, and H9 avian influenza viruses, so named for their hemagglutinin surface antigen, can each be matched with nine possible neuraminidase surface antigens, N1, N2, N3, etc. Thus, there could be H5N1 through H5N9, H7N1 through H7N9, and H9N1 through H9N9 strains" (2005, p. 327).

H9 viruses seem to be of low pathogenicity, while H5 and H7 viruses have been found to be highly pathogenic for birds; however, low pathogenic forms of these viruses appear to cause most outbreaks among poultry, producing only mild or imperceptible illness and low mortality rates (Imperato, 2005). Nevertheless, both the H5 and H7 strains have the potential to develop high levels of pathogenicity, in which case mortality rates in poultry flocks can reach 100 percent. The natural history of avian influenza viruses is characterized by spread through infected nasal, respiratory, and fecal material, and a reservoir state in healthy birds. Outbreaks of avian influenza in poultry flocks have regularly occurred in many areas of the world, including the United States (Imperato, 2005).

There have been at least 16 outbreaks of H5 and H7 avian influenza since 1997 documented among poultry by the U.S. Department of Agriculture; furthermore, low pathogenic subtypes of avian influenza viruses have been found to be endemic in wild waterfowl and migratory birds (Imperato, 2005). Although the numerous subtypes of avian influenza are of low pathogenicity, some are known to cause high mortality rates among birds, other animals, and humans. The one of particular concern in recent years is the aforementioned H5N1, which has increasingly been the source of epizootics among animal species and some cases in humans (Imperato, 2005).

Although the majority of human cases of avian influenza appear to have been acquired from birds, one instance of possible human-to-human transmission may have taken place in Thailand in September 2004 (Imperato, 2005). The first officially recorded case of the transmission of H5N1 from chickens to humans took place in Hong Kong in 1997; during that outbreak, eighteen people were hospitalized and six died (Imperato, 2005). Since that time, other human cases have been reported from infection with different strains of the virus, including H9N2, H7N2, H7N3, H7N7, and H5N1; the majority of these cases were linked with poultry outbreaks, though there are a few cases in which the sources of infection could not be determined (Imperato, 2005).

Although there is still no solid evidence that the H5N1 virus has reassorted its genetic segments with a human influenza A virus, the potential for this mutation has caused the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) to launch a number of preventive initiatives and to promulgate guidelines and recommendations for both public health practitioners and individuals (Imperato, 2005).

Conclusion

The research showed that there is a very real potential for an avian influenza pandemic in the future, and there remains an insufficient amount of effective vaccine to address the current incarnation of the H5N1 virus, not to mention any more virulent mutations that might emerge in the years to come. In this uncertain but potentially threatening environment, it is useful to develop a broad-based assessment of the realities involved in order to provide meaningful and timely responses.