Why it is becoming a serious issue now?

      It is becoming a concerning issue because of just three months after India declared itself to be free of the avian influenza outbreak, the highly pathogenic avian influenza subtypes, H5N1 and H5N8, have been reported from a dozen epicentres in four States — Rajasthan, Madhya Pradesh, Himachal Pradesh and Kerala. Also, thousands of poultry birds have died in Haryana, while Jharkhand and Gujarat, too, have sounded an alarm; the cause in these three States is still unknown. Lakhs of birds have died, including poultry, ducks, crows and migratory birds, in the country in the past 10 days. The central government, along with the Department of Animal Husbandry and Dairying, has increased vigilance for potential hot spots after confirmed cases. In Kerala, 23,857 birds died in Kottayam and Alappuzha districts. Over 1,700 ducks died at a farm in Kottayam. In Rajasthan over 600 birds have died in the last one week. The government asked for vigil and monitoring of the bird flocks where there have been confirmed cases in 16 of the 33 districts.

     Influenza is a very serious illness for anyone at high risk. Certain diseases that place people at high risk include chronic lung diseases such as asthma, COPD, bronchiectasis, or cystic fibrosis, heart disease, chronic kidney disease, diabetes or other chronic metabolic disorder, morbid obesity, severe anaemia (including sickle cell anaemia), diseases (HIV, AIDS) or treatments (steroids, chemotherapy) that suppress immunity, liver disorders and children and adolescents who are receiving long-term aspirin therapy.

When the influenza virus enters the host cell?

           The influenza virus enters the host cell by having its hemagglutinin bind to the sialic acid found on glycoproteins or glycolipid receptors of the host. The cell then endocytoses the virus. In the acidic environment of the endosomes, the virus changes shape and fuses its envelope with the endosomal membrane. This is followed by a signal to release the virus nucleocapsid into the host cytoplasm. From there, the nucleocapsid travels to the host nucleus.

           In the host nucleus, the virus does primary transcription to produce necessary proteins for replication. The primary transcription involves what is known as "cap snatching." What this means is that the viral endonuclease (PB2) cuts the 5' methylguanosine cap as well as ten to thirteen nucleotides from the RNA. This is then used as the primer for the transcription of the protein PB1, a viral transcriptase. In influenza A and B, ten proteins result from the translation of the eight segments of the genome, including hemagglutinin, neuraminidase, PB1, PB2, nucleoprotein, another RNA polymerase complex, two matrix proteins, and two NS proteins.

          Once the initial proteins are made, then eight complementary positive-sense RNA strands are made from the eight negative-sense RNA segments (at least in influenza A and B. . . influenza C has seven segments). These lack the 5' capped primer, as well as the 3' poly (A) tail found in the mRNA. From this cRNA, a negative-sense RNA is produced. Various proteins then help this negative sense RNA exit the nucleus and into the cytoplasm of the host.

          In the meanwhile, in the cytoplasm, the hemagglutinin and neuraminidase have undergone glycosylation, polymerization, and acylation. The hemagglutinin, neuraminidase, and the matrix protein two (M2) all travel together to the plasma membrane. There the proteins meet with the other matrix protein (M1) and begin the bidding process. At least eight RNA segments come to the site (the mechanism is not completely known), and the virus buds. The neuraminidase finally destroys the sialic acid receptors on the membrane, thus allowing the virus to leave the cell.

Where the first case of avian influenza noticed in human?

       Bird flu outbreaks have been affecting poultry around the globe for decades, and culling of infected birds has been a common measure to contain the spread. But it was in 1997 when humans are first known to have contracted bird flu following an outbreak in a live bird market of Hong Kong. It was the H5N1 strain of the virus, and 6 out of 18 infected humans died of the disease. Since it has been detected in poultry and wild birds in more than 50 countries in Africa, Asia, Europe, and the Middle East. Six countries are considered to be endemic for Asian HPAI H5N1 virus in poultry (Bangladesh, China, Egypt, India, Indonesia, and Vietnam). Since its widespread re-emergence in 2003, rare, sporadic human infections with this virus have been reported in Asia, and later in Africa, Europe, and the Middle East. Human infections with Asian H5N1 viruses have been associated with severe disease and death. Most human infections with avian influenza viruses, including HPAI Asian H5N1 viruses, have occurred after prolonged and close contact with infected birds. Rare human-to-human spread with this virus has occurred, but it has not been sustained and no community spread of this virus has ever been identified.

      Since its widespread re-emergence in 2003, rare, sporadic human infections with this virus have been reported in Asia, and later in Africa, Europe, and the Middle East. Human infections with Asian H5N1 viruses have been associated with severe disease and death. Most human infections with avian influenza viruses, including HPAI Asian H5N1 viruses, have occurred after prolonged and close contact with infected birds. Rare human-to-human spread with this virus has occurred, but it has not been sustained and no community spread of this virus has ever been identified.

In January 2014, Canada reported the first human infection with HPAI Asian H5N1 virus in the Americas. This was an “imported” case occurring in a traveller who had recently returned from China.

Subsequently, several other strains of the virus such as H5N2 and H9N2 spread from animals to humans, thus becoming a global public health concern.

Who discovered the influenza vaccine?

In 1940, Thomas Francis, Jr., MD and Jonas Salk, MD serve as lead researchers at the University of Michigan to develop the first inactivated flu vaccine with support from the U.S. Army. Their vaccine uses fertilized chicken eggs in a method that is still used to produce most flu vaccines today. The Army is involved with this research because of their experience with troop loss from flu illness and deaths during WWI. This original vaccine only includes an inactivated influenza A virus.

• In 1940, First-generation mechanical ventilators become available. These machines support breathing in patients suffering from respiratory complications and influenza B viruses are discovered.
• In 1942, a bivalent (two-component) vaccine that offers protection against influenza A and influenza B viruses is produced after the discovery of influenza B viruses.
• In 1945, Inactivated influenza vaccine is licensed for use in civilians.
• In 1978, the first trivalent flu vaccine was introduced. This vaccine typically includes two influenzas A strains and one influenza B strain.
• In 2012, the first quadrivalent flu vaccine was licensed in the United States. Since then, a variant of the quadrivalent vaccine has become commonly recommended by WHO each year.

How can we know if someone suffering from influenza?

A person who is suffering from influenza, have few signs and symptoms

These types of viral zoonotic disease beginning from a mild upper respiratory problem, fever and cough to rapid progression to severe pneumonia, acute respiratory distress syndrome, shock and even death. Gastrointestinal symptoms such as nausea, vomiting and diarrhoea have been reported more frequently in A(H5N1) infection. Conjunctivitis has also been reported in influenza A(H7). Disease features such as the incubation period, severity of symptoms and clinical outcome varies by the virus causing the infection but mainly manifests with respiratory symptoms.

• Common initial symptoms are high fever (greater than or equal to 38°C) and cough followed by symptoms of lower respiratory tract involvement including dyspnoea or difficulty breathing.
• Upper respiratory tract symptoms such as sore throat or coryza are less common.
• Other symptoms such as diarrhoea, vomiting, abdominal pain, bleeding from the nose or gums, encephalitis, and chest pain have also been reported in the clinical course of some patients.
• Complications of infection include severe pneumonia, hypoxemic respiratory failure, multi-organ dysfunction, septic shock, and secondary bacterial and fungal infections.
• The case fatality rate for A(H5) and A(H7N9) subtype virus infections among humans are much higher than that of seasonal influenza infections.
• Symptoms of influenza can include: Sudden onset of high fever, Headache, muscle aches and joint pain, Cough (usually dry), Chills, Sore throat, Nasal congestion and runny nose, Fatigue and Stomach symptoms such as nausea, vomiting or diarrhoea may occur but are more common in children than adults.
• Flu symptoms in school-age children and adolescents are similar to those in adults. Children tend to have higher temperatures than adults, ranging from 103°F to 105°F. Flu in preschool children and infants is hard to pinpoint since its symptoms are so similar to infections caused by other viruses.