Lack of H5N1 Avian Influenza Transmission to Hospital Employees, Hanoi, 2004
Background:
Influenza type A virus is prevalent in birds, humans, etc.
One subtype of influenza, H5N1, has infected chickens in several different
continents and has spread to humans as well, with a very high mortality
rate.
This highly pathogenic avian
influenza has been present in sporadic outbreaks in poultry- often reported as
“fowl plagues.” The first fowl plague
was reported in Italy in 1878. Due to the human influenza pandemics that
happened in the mid twentieth century, more attention was paid to monitoring
the virus in avian species by the 1970’s. It was reported that wild waterfowl
harbor all of the influenza A virus sub types and these subtypes (H5 and H7) were primarily responsible for
the high mortality in poultry within the United States. Although the avian
influenza occurred all around the world by 1959, the outbreaks were
geographically confined in specific
regions within each country, revealing that the diseases were endemic to
specific regions. However, due to globalization, H5N1 influenza virus has
spread across the globe significantly. One additional factor that may have contributed to the avian influenza outbreak is the increase of poultry production and dissemination
by a factor of 436% since 1970. Because the demand for poultry has
risen significantly, there has been a subsequent increase in intensive poultry production which often leads to over crowded facilities
with poor health conditions for the animals and easier spread of disease due to
closer contact. Furthermore, higher demands for poultry has also led to genetic modifications for breeding
mechanisms (for greater production), leading to less genetic diversity and subsequent higher
susceptibility for disease and infection. The infection from avian to human
populations is deadly, but rare and often occurs when one comes into contact with diseased birds.
A photo of avian influenza in chicken stomach cells
Primary Source Synopsis and Analysis:
In this article, a cross
sectional survey was administered amongst employees in a hospital in
Vietnam who were exposed to H5N1
patients to see if human to human transmission of influenza type A occurred. Because
of the host barriers to infection (different cell receptors) avian to human
transmission of influenza is rare, as it requires either a genetic
mutation or genetic reassortment with a human influenza strain. However the
study of household and social contacts of Hong Kong H5N1 patients revealed that
human to human transmission of H5N1 viruses of purely avian origin is possible.
The main concern is that if this highly pathogenic influenza virus has the ability
to transmit from person to person it could cause a potential influenza
pandemic. However, research is showing that although human to human transmission
is possible, it is not sustainable, but over time with genetic alterations, the
potential for the H5N1 to act differently exists.
From December 27, 2003, to January 19, 2004 four children from the age of four to twelve were confirmed to have H5N1 infection and there was one case of probable infection, who were admitted to the National Pediatric Hospital in Hanoi, Vietnam. Employees who came in contact and had possible exposure to the patients with (or with potential infection) H5N1 were surveyed and tested for signs of potential infection. Of the 83 surveyed hospital employees none tested positive for antibodies to influenza A H5N1. There are a number of potential reasons why none of the employees tested positive for the disease. These include the “lack of infectivity of the patients at the time of admission, the effective use of personal protective equipment (PPE) and infection control, low sensitivity of the antibody detection method, lack of susceptibility of HCWs, or a lack of transmissibility of this particular H5N1 strain."
From December 27, 2003, to January 19, 2004 four children from the age of four to twelve were confirmed to have H5N1 infection and there was one case of probable infection, who were admitted to the National Pediatric Hospital in Hanoi, Vietnam. Employees who came in contact and had possible exposure to the patients with (or with potential infection) H5N1 were surveyed and tested for signs of potential infection. Of the 83 surveyed hospital employees none tested positive for antibodies to influenza A H5N1. There are a number of potential reasons why none of the employees tested positive for the disease. These include the “lack of infectivity of the patients at the time of admission, the effective use of personal protective equipment (PPE) and infection control, low sensitivity of the antibody detection method, lack of susceptibility of HCWs, or a lack of transmissibility of this particular H5N1 strain."
A Vietnamese nurse with a patient infected with H5N1 in the National Pediatric Hospital in Hanoi
http://english.vietnamnet.vn/fms/society/98281/another-a-h1n1-death-confirmed-in-vietnam.html
Although the
risk for the human to human transmission of the avian H5N1 virus is low, I believe that the
fatal cases of recent H5N1 cases reveal the vital importance of hospital staff taking
serious protective measures to ensure the spread of disease is limited and safety and
health of other patients and health care workers. Effective use of personal protective equipment can include proper usage of face masks, gloves, and body suits in potentially infectious scenarios or encounters. This represents a very vital preventative measure health care employees and physicians must prioritize when dealing with patients with all transmissible infections- but especially so in the case of the avian influenza, whose nature of transmission is not fully understood at this time.
The article ends with stating that the risk of human to human transmission of the H5N1 virus could increase in the future so every H5N1 case should be monitored and managed by health care workers and physicians to ensure that the spread is controlled as much as possible. A potential study that can be done is whether exposure to the avian influenza will impact the susceptibility of any of the 83 health care employees in the face of future influenza type A or B exposures in the future. This cross sectional survey can be done over a period of several years by monitoring the infection rates of health care workers who were exposed to the H5N1 versus health care employees who had no exposure to H5N1. Infection rates can then be compared to determine if there is any potential association exposure to H5N1 and ones susceptibility to future cases of influenza.
The article ends with stating that the risk of human to human transmission of the H5N1 virus could increase in the future so every H5N1 case should be monitored and managed by health care workers and physicians to ensure that the spread is controlled as much as possible. A potential study that can be done is whether exposure to the avian influenza will impact the susceptibility of any of the 83 health care employees in the face of future influenza type A or B exposures in the future. This cross sectional survey can be done over a period of several years by monitoring the infection rates of health care workers who were exposed to the H5N1 versus health care employees who had no exposure to H5N1. Infection rates can then be compared to determine if there is any potential association exposure to H5N1 and ones susceptibility to future cases of influenza.
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