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Epidemiology of Avian Influenza and Prevention Strategies

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Three previous influenza pandemics, which claimed thousands of lives in the United States, have occurred within the last century. The Spanish flu in 1918 resulted in the deaths of an estimated half a million people. In 1957 the Asian Flu took the lives of 70,000 people. In 1968 the Hong Kong Flu killed 34,000 people (Howard, 2007). Such earlier events have made the world and political leaders, as well as the public, afraid of a pandemic threat.

Epidemiology of Avian Influenza and Prevention Strategies

Avian Flu: Natural History and Cause

A virus naturally carried by wild birds causes avian flu, more popularly known as “bird flu,” (Jan 2007). The Avian Flu virus is an influenza virus of type A. Influenza viruses of type A can be found in human beings, birds and other mammals. This is the only form of influenza virus in history that has caused pandemics (Beigel, 2008).Epidemics

Just four known strains of avian influenza viruses among them H5N1, H7N3, H7N7 and H9N2 have been found to affect humans. H5N1 is the most strongly pathogenic of the four. Because of two main factors, it is the greatest source of warning. The first explanation is that it has been used in the most serious incidents and even suicides. Another concern is the ability of the virus to mutate into a form that could be more transmissible to humans. The virus can improve its ability to infect humans in two major ways, first is through genetic reassortment, and the second is through a gradual mutation as part of their adaptation. Current data all implicate handling of dead or infected birds as the primary cause of infection with the avian flu virus. Other sources could be direct and direct contact with the excreta of infected birds. The avian virus does not as yet infect humans easily. (WHO, 2006)

When humans are infected, there is an exchange of material between the human virus strain and the avian virus strain. This may result in a new, virulent, highly communicable virus to which humans would have little or no immunity (Goldrick, 2004). Experts agree that the H5n1 strain may mutate into that form that can be easily transmitted between humans (Howard, 2007).

The avian flu virus cannot survive without a host. The virus spreads through migratory birds. These birds expel out the virus through their nasal secretions, saliva and excreta. When domestic birds such as chicken and ducks come in contact with the virus, they die since they have no natural immunity to it. The World Health Organization (WHO) reported that outbreaks of the Avian influenza type A (H5n1) occurred in domestic poultry in Early in 2004 the World Health Korea, Japan, Vietnam, Thailand, Cambodia, China, Indonesia, and Laos early in 2004. According to the report, millions of poultry either died or were destroyed. (Goldrick, 2004)

The influenza virus in humans adheres to and attacks epithelial cells of the upper respiratory tract. Replication of the virus in the affected cells leads to a series of events that cause coughing. Respiratory droplets are then expelled through talking, coughing and sneezing. The sizes of the droplets that are expelled determine the distance that it can travel. Droplets of smaller diameter remain in the air for a lengthier period and thus go farther (Beigel, 2008). Larger droplets transmit the virus to persons approximately within 3 feet. Transmission through contact with another person also occurs (Howard, 2007).

Symptoms of the avian flu virus are similar to that of the seasonal flu, which includes fever, cough, and malaise. The course of the illness lasts to approximately three days; the period of communicability lasts for more than five days (Howard, 2007). The spread of the virus could be aided by birds migrating from the place as well as human migration. Travellers who enter the country who may not yet show the symptoms may be the source of infection. Still another way is by travelling to other countries affected by the virus and closely coming in contact with infected birds.

Frequency and Distribution

The avian influenza was first implicated in the death of wild cats in 1994. The virus has then spread throughout Asia. There has also been a few isolated cases documented in France and Germany. As of September 2007, there have been 328 verified cases of avian influenza (Howard, 2007). According to data gathered from a study conducted by Onizuka and Hagihara influenza outbreaks commonly start in cities, and after a short period, it spreads to the rural areas. Avian influenza can affect anybody, male or female, but children with a depressed immune system, the elderly and the sick are at a greater risk. Vaccinations for these population groups that are at higher risk are highly recommended. (Goldrick, 2004) Poultry farmers and other individuals who have handle birds closely as part of their jobs have a high risk for acquiring the virus (Tzeng and Yin, 2007).

National/International Agency

In the event of a pandemic, the resources of the US healthcare system would be stretched beyond its limits. A shortage of medical supplies and healthcare personnel is anticipated (Howard, 2007). The development of preparedness strategies for dealing with a potential influenza pandemic is still a priority globally. Due to a shortage and lack of drugs that are effective against the virus, infection control measures must be persistently improved and implemented (Tzeng and Yin, 2007). The World Health Organization (WHO) is collaborating with international partners, one of which is CDC, on the international monitoring of the Avian flu virus and as well as progress on the vaccine (Jan 2007). In another attempt to delay the spread of the virus globally, countries affected by the avian flu have undertaken proactive measures by slaughtering poultry, vaccinations of poultry and carrying out quarantine programs. The United States Department of Health and Human Services (DHHS) has banned the importation of birds and bird products from countries who have reported cases of avian flu. Other additional prevention efforts are geared towards training state laboratories in identifying the virus and coordination between states in planning efforts (Jan 2007).

  • State Efforts

North Carolina is among the states with the highest number of influenza-associated deaths in children. The deaths were due to complications of ordinary flu. If avian flu were to affect this state, deaths not only in children would reach higher proportions. (Goldrick, 2007) As part of their efforts in preparedness, various counties in North Carolina are offering the public up to date information on basic preparedness strategies.

  • Local Agency

Local efforts constitute city and state public health departments working closely with national agencies to ensure an effective response to a possible pandemic outbreak. Continuous monitoring, communication strategies between agencies and the people, as well as pandemic preparedness response plans, should be in place. (Jan 2007) For example, Burke County in North Carolina offers information about the Avian flu virus in their website and as part of their preparedness plan.

Several communities throughout the nation have also taken steps for avian flu preparedness. For instance, the first of many seminars about readiness of bird influenza was conducted in Orange County, Florida, on April 5, 2006. Workshops soon followed it in other communities throughout the country. These seminars serve as how community leaders are educated regarding the need for an action plan that could be carried out in case of a pandemic to avoid tremendous casualties that would result otherwise (Howard, 2007).

  • Tertiary Prevention

Healthcare professionals play a significant role in the prevention, delay and management of an outbreak. They must have a detailed plan in coping with and managing a pandemic threat (Howard, 2007). Health care workers must attend to influenza patients using droplet precautions. Infected persons, who are not in private rooms, must be placed in a room with persons of the same diagnosis. Visitors and health care providers must religiously practice infection control procedures such as hand washing at every patient contact and wearing masks, gloves and gowns when appropriate. When the patient needs to go out of the room or needs to be transported, he must wear a surgical mask to reduce dispersal of the virus through droplets (Beigel, 2008).

  • Secondary Prevention

Home health care nurses have an even greater burden than nurses working in hospitals. They must be prepared for the avian flu by considering any special needs of their clients and by being alert for early symptoms in their client. There is a necessity to coordinate with local health care agency when avian flu cases are apparent. The home health nurse also needs to deal with mental health and physical health brought about by avian influenza by providing clients with adequate support and referral to other agencies when necessary. Home health nurses are at an opportune place to provide information to families, which would help greatly in preventing the spread and managing avian flu, and they must take advantage of that (Jan 2007).

  • Primary Prevention

There are specific measures that can prevent transmission, including washing hands frequently, avoiding being in crowds or groups, decreasing contact with others, always maintaining a distance of at least three feet between people when possible, refraining from shaking hands and the advising people who manifest the symptoms to stay at home (Redlener, 2006).

Another preparedness strategy that must not be overlooked is the use of vaccines. Experts concur that the development of an effective vaccine that can be made available to the public should take precedence as a preparedness strategy. The use of techniques other than the conventional egg-based development of vaccines which is time-consuming is also being studied. Researchers in vaccine production are further challenged to find a way to reduce the dose required for the vaccine. As all of these are being done, the evolution of the avian virus is also closely followed to detect more dangerous and easily transmitted virus strains. There is a need to develop the vaccines in a shorter amount of time than is traditionally being done (Hampton, 2007).

As vaccine research is going on, other areas for outbreak prevention are also being explored. Onozuka and Hagihara, (2008), conducted a study on the significance of using a permutation model and space-time permutation scan statistics in determining influenza outbreaks during its onset and ascertaining the pattern of spread of the flu. The results of the study imply that geography is a factor in the range of influenza. Scan statistic may be useful in identifying valid outbreaks that may not be detected by traditional monitoring methods. This may, in turn, lead to better preparedness of the areas that may be affected by the outbreak as they will be forewarned earlier.

There are existing entities in the community that can also be of great help in the management of a pandemic. The Veteran’s Affairs is a prime example of an unrecognized partner that could be utilized by local and national health care agencies in case of an epidemic. An exercise conducted by Lurie et al. (2008), found that existing communication and coordination between Veteran’s Affairs and the local and regional emergency planners are inadequate. The agencies involved could work with each other, share resources and reduce each other’s burden if lines of communication and collaboration are more efficiently used.

Influenza viruses have been affecting humans for centuries. This fact, though, does not mean that we have become better equipped to deal with an outbreak. The Avian influenza A threat is real. The virus continues to mutate. At this time, humans are only at risk from infected birds and not from human-to-human contact. The best strategy is to plan by being aware of what the threat is all about. (January 2007).

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