Avian Influenza

Avian Influenza is a virus that infects wild birds (such as ducks, gulls, and shorebirds) and domestic poultry (such as chickens, turkeys, ducks, and geese). There are flu virus variants for birds just as there are for humans and, as with people, some forms of the flu are worse than others. Infected birds shed avian influenza virus through their saliva, mucous and feces.

Avian influenza viruses are either high or low pathogenic viruses (HPAI and LPAI, respectively) depending on the molecular characteristic of the virus and its ability to cause disease and mortality in chickens.

Poultry infected with LPAI viruses may show mild signs of the disease or none at all. Infections caused by HPAI can cause death. Both HPAI and LPAI can spread quickly through flocks.

Avian Influenza viruses do not normally infect humans. However, sporadic human infections with avian Influenza viruses have occurred. Human infections with avian influenza viruses can happen when virus gets into a person’s eyes, nose or mouth, or is inhaled. Illness in humans from avian influenza virus infections have ranged in severity from no symptoms or mild illness to severe disease that resulted in death.
Avian Influenza

Swine Influenza Virus H1N1

Viruses of the classical H1N1 lineage were the dominant cause of influenza among pigs in North America from their first isolation.

Classical H1N1 viruses have also been isolated from pigs in South America, Europe and Asia.

There is only limited evidence of maintenance of human H1N1 influenza viruses after natural introduction into swine populations but human H3N2 viruses have been recovered frequently from pigs in Asia and Europe.

Experimental infection studies have shown that pigs can be infected with a wide range of avian influenza virus (AIVs) and naturally acquired infections of pigs with AIVs have also been documented from multiple areas of the world.

In particular, an avian H1N1 virus introduction into pigs Europe in late 1970s spread throughout much of the European continent and United Kingdom and ultimately became a dominant cause of swine flu in these areas.

These avian-like H1N1 viruses have also undergone genetic/antigenic drift and have spread from pigs to domestic turkeys.

The occurrence of influenza virus infections in pigs poses two important public health issues: zoonotic infections of people with swine influenza viruses and the potential for pigs to serve as hosts for the creation of novel viruses of pandemic potential for the human population.

Infections with swine influenza viruses is generally limited to the respiratory tract, with virus replication demonstrated in epithelial cells of the nasal mucosa, tonsils, trachea, lungs and tracheobronchial lymph nodes.

Swine flu is an acute infections and virus clearance is extremely rapid. In most experimental studies, nasal virus shedding begins on day 1 postinoculation (P1) and ceases within 7 days.

Likewise, swine influenza virus could not be isolated from lungs or other respiratory tract tissues after day 7.

Infections with H1N1, H1N2 and H3N2 subtype viruses are clinically similar, and viruses of all subtypes have been associated with acute respiratory episodes in most European countries.

Disease onset is sudden, after an incubation period of 1 – 3 days. Disease signs typically appear in a large percentage of animals of all ages within a herd or epidemiological unit.
Swine Influenza Virus H1N1

H5N1 infection

Humans most commonly acquire H5N1 influenza infection following contact with infected poultry, either through direct contact, plucking and preparing diseased birds, handling fighting cocks, playing with infected poultry or consuming infected poultry.

Human infections with highly pathogenic avian influenza viruses of the H5N1 subtype were first reported in 1997 in Hong Kong, when 18 people were infected and six people died.

Since human to human transmission of H5N1 influenza is inefficient and humans are most commonly infected through direct contact with infected poultry, the most efficient form of control is to avoid or limit contact with sick poultry or suspected cases of H5N1.

Early clinical features of H5N1 infection include persistent fever, cough, and respiratory difficulty progressing over 3-5 days as well as lymphopenia on admission to the hospital.

Other initials symptoms include headache malaise, muscle aches, sore throat, gastrointestinal upset and eye inflammation. All these symptoms are non-specific and may also be associated with currently circulating human seasonal influenza virus subtype.
H5N1 infection

The word of Influenza

The word of Influenza
The word influenza is Italian for influence, as in the astral or occult influence of a visitation or outbreak that affects many people at the same time. First used in 1504, the word signified any disease epidemics.

In a severe flu outbreak of 1743 the word influenza was applied to the epidemic that began in Italy and spread throughout Europe.

Since then, the influenza, shortened to flu, means a serious infectious disease characterized by muscle and joint aching, prostration, and respiratory congestion with fever and headache.

It was not until 1931 that an influenza virus was identified in pigs, and finally in 1933 a human influenza virus was discovered by three researchers: Smith, Andrewes, and Laidlaw.

Both of these viruses were closely related to the Spanish flu virus of 1918. During the time of the 1918 flu pandemic, however, the suspected culprit was a bacterium named Hemophilus influenza. Viruses had not yet been discovered.

Although most people consider the flu simply and annoyance, and possibly a danger to seniors in poor health, influenza has been responsible for repeated, devastating worldwide pandemics capable of bringing entire nations to their knees.

It is hard to imagine today, but in 1918 the entire world was in the clutches of a deadly flu virus. The 1918 flu still remains the greatest plague the world has ever seen.
The word of Influenza