Influenza viruses can be categorized into three. These subtypes are named as A, B and C with A type viruses infecting humans, birds, horses, pigs and other animals. The natural hosts for these viruses are wild birds. A review of available substantiation on potential transmission of avian influenza indicates that A virus is a proofed cause of epidemic. Influenza B on the other hand are viruses found simply in humans. Studies indicate that compared to other types, influenza C viruses cause placid sickness in humans.
Influenza A viruses has various categories which are defined by the haemagglutinin (H) and neuraminidase (N) proteins existing on the virus surface. The H subcategories are epidemiologically vital, as they determine the capability of the virus to bind to and find their entry into the cells, where the virus then multiplies itself. The N subtypes on the other hand controls the discharge of new occurring virus from the cells. Research indicates that some subtypes have low capacity to cause ailment known as pathogenicity. Other subtypes have soaring pathogenicity. Human influenza A has various subtypes including H1N1, H1N2 and H3N2. These subtypes have brought a major epidemic in humans.
Avian influenza commonly known as bird flu is brought by avian influenza A viruses. It has its transmission usually taking place between birds. H5N1 a subtype of avian influenza A virus is very infectious amongst birds. In the few cases that the virus is transmitted from birds to humans, it can be a source of pneumonia, many organ failure and time and again death. According WHO, there had been over 200 cases of transmission to humans as at May 2006 accompanied by 115 deaths.
Research indicates that wild waterfowl are the usual carriers of all avian influenza A viruses. Most infected birds with the virus shows no symptoms, even when removing large amounts of infectious virus from their bodies. These highly infected birds act as carriers of the virus, and they transmit to other birds. The virus is typically passed from wild birds with low pathogenicity and then it mutates in domestic poultry.
The prevailing apprehension concerned with the HPAI H5N1 virus is that it may transform into a structure that is extremely communicable for humans and that transmits effortlessly from one person to another. Nobody will possess immunity for the epidemic because no one will have been open to it or come up with antibodies for it. For such an outbreak no prevention vaccine with assured effectiveness can be prepared in advance making it even more dangerous. Vaccines are being organized and kept in advance, hoping that they might match the epidemic strain of the virus. Research shows that a pandemic strain may exhibit distinctiveness of pathogenicity that might not be known without delay. Such alterations may possess effects for the effectiveness of control measures introduced during pre-pandemic development. Nevertheless, it is known that some proceedings, such as amplification of personal hygiene methods will cut down human-to-human conduction of the virus. This will assist in curbing or slowing the multiplication of the pandemic virus.
The type A (H1N1) virus known as the swine flu circulates and cause recurring influenza and in the past, very sporadically these viruses from swine have contaminated people. The virus is highly contagious just like the H5N1 virus. Originally, studies indicated that the virus had its origins from pigs but there is no substantiation that the present spread of virus is coming from the pigs. Avian flu and swine flu can be spread from one person to another. This happens when an infected person sneezes or coughs among non infected people. This is one striking characteristic between them. Research shows that there is strong likelihood that people may become contaminated by touching anything with flu viruses. Both influenza pandemics occurred when they emerged and got transmitted speedily across the globe mainly because there was no previous immunity against this virus in the past. This is a very common characteristic with the all influenza viruses.
H1N1 and H5N1 viruses were new virus when they emerged and little was known about them. Most people across the globe had no immunity to them. Based on evidence presented by history and scientific research, influenza pandemics can cause death of millions of people per outbreak. In both cases, there was no pandemic influenza vaccine at the beginning and there were no preparations for the virus. Characteristically, the percentage of deaths from past pandemics is estimated using statistical models and it is very high at the beginning. A more precise estimation of mortality from both pandemics was done using statistical models. The results showed that some groups of people appeared to be at higher danger of more complex or relentless infection these groups included the pregnant women, infants, and young children predominantly under age two years old.
This characteristic has not been proven for the H1N1 virus. However, lower respiratory tract (LRT) cells to which the virus attaches to are not known for humans. It has been shown that H5N1 virus attached principally to type II pneumocytes, alveolar macrophages cells in the human LRT. This pattern was very closely seen in cat and ferret tissues. The results explain, partly, the localization and rigorousness of H5N1 virus in humans.
Studies conducted on transmission of avian influenza and swine flu indicated that both are transmitted by breathing of transferable droplets and by direct contact, and probably by indirect contact onto the upper respiratory tract or mucus membranes. The comparative effectiveness of the different routes of transmission has not been defined for both H5N1 and H1N1. H5N1 infections verification is regular with bird to human and environment to human and narrow, non persistent human to human transmission. Studies conducted in 1997 showed that disclosure to live poultry in a short time ahead of disease beginning was linked with infection in humans. However, there was no significant danger linked to eating or dressing of poultry products.
Other significant studies showed that many patients have had a past associated with direct contact with poultry for avian flu and direct contact with pigs for the swine flu. In both cases, the patients were either involved with treating a diseased animal or bird, mass culling of poultry, plucking and dressing of contaminated birds. Other studies suggested that handling infected ducks and utilization of its blood was a very strong method of infection. The incubation period of avian influenza (H5N1) is longer than that of swine flu (H1N1). Due to the survival of avian influenza (H5N1) in the environment, studies indicate that several other means of transmission are hypothetically possible.
Compared to other influenzas affecting the humans, avian flu and swine flu are potentially very dangerous. This is because very little is known about their manifestation. Avian flu exceeds other influenzas affecting the humans in terms of infection. The new viruses have also caused a lot of death and infection that are not usually viewed in influenza infections. Many deaths due to the avian and swine influenza have affected the younger people together with those who are potentially healthy. Both infections are more infectious in pregnant women, children and people with persistent lung infections.
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