Some insights about bird flu and Tamiflu (oseltamivir)

H5N1 virus is taken by the Central Institute of VSDT

Why is it called bird flu? As a bird flu virus; These viruses are naturally found in birds. Wild birds worldwide carry the virus in the gastrointestinal tract but often do not get sick from the virus. However, the flu is very widespread in birds and can make birds like chickens, ducks . sick and die.

The avian / bird flu virus does not normally infect humans, but many cases of bird flu infection have occurred since 1997.

How is bird / poultry flu virus different from human influenza virus? The avian / bird A virus also has many subtypes; These are also different because there are several proteins on the surface of influenza A virus (hemagglutinin HA protein and neuramidase NA).

Influenza A virus has up to 16 HA subcategories and 9 NA subtypes; there may also be other combinations of HA and NA proteins, each of which creates another. All subtypes of influenza A virus can be found in birds.

However, when talking about the 'bird flu' virus, it refers to the sub-forms of influenza A, which mainly fold in birds. These bodies usually do not infect humans but are still contagious. When talking about 'human influenza viruses', it is about common side effects in humans.

It is only known that three subtypes of human influenza A virus (H1N1, H1N2 and H3N2), it is possible that some genes of human influenza A virus originated from birds. Influenza A virus often changes and can adapt over time to infect and spread in people.

Symptoms of bird flu in humans? There may be typical flu-like symptoms (fever, cough, sore throat and muscle aches) or eye pain, pneumonia, severe respiratory disease (such as acute respiratory failure) and many life-threatening complications other. The symptoms of bird flu in humans depend on which virus causes the disease.

How is bird flu spread? The infected saliva, nasal passages and droppings contain viruses. Birds and poultry are infected with viruses when exposed to the above wastes or on contaminated surfaces. It is believed that most cases of avian influenza virus infection in humans are caused by contact with infected birds or contaminated ground. The spread of avian influenza virus from sick people to healthy people is still rare and has not been found to spread far beyond one person.

The risk of pandemic avian influenza in humans? H5N1 virus usually does not infect humans. However, in 1977 there was the first case of bird-to-human transmission in a bird flu outbreak in Hong Kong. The virus caused severe respiratory distress in 18 people, 6 of whom died. Since that day, there have been no more cases of H5N1 in humans.

Human cases of H5N1 have recently occurred in Khmer, Thailand and Vietnam, coinciding with large outbreaks of bird flu. The World Health Organization has also reported cases of human infections in Indonesia. Most of these cases occur in people who have been exposed to poultry or contaminated areas, but it is thought that there have been several cases of H5N1 infection from human to human. So far, the transmission of H5N1 from humans to humans is still rare and has not exceeded 1 person but influenza viruses are likely to change. Scientists fear that the H5N1 virus could one day infect humans and spread easily from person to person. Because these viruses do not regularly infect humans, they do not generate much immunity to protect them. When the H5N1 virus becomes easily contagious and spreads easily from person to person, the pandemic will break out, so experts are closely monitoring the evolution of bird flu in Asia.

How to treat bird flu in humans? The H5N1 virus currently developing in Asia has caused illness and death in people who are resistant to amantadine and rimantadine, two antiviral drugs commonly used to treat influenza. Two other antiviral drugs, oseltamir and zanamavir, may work to treat the flu caused by H5N1, but more research is needed on the effectiveness of these drugs.

Tamiflu is a brand name of oseltamir, packaged in a 75mg blue / yellow capsule in a hard gelatin shell or a white, fruity emulsion, which is a well-known anti-bird flu drug. Antiviral drugs, preventing the effects of viruses in the body; to treat flu-caused illness in newly symptomatic patients; also used to prevent influenza virus infection; Also used for other purposes.

If you have kidney disease, liver, chronic diseases or other serious diseases, you should not take the medicine or if you have to use it, you must adjust the dose, special monitoring. Tamiflu according to FDA classification is in Table C which means that it is not clear if the drug is harmful to the fetus, so if you are pregnant, do not use the medicine without telling the physician. It is also unclear whether Tamiflu is secreted in milk and is harmful to nursing infants, so do not take the drug if breastfeeding. The safety and efficacy of Tamiflu have not been determined for people under 18 years of age in the treatment of influenza viruses and children under 13 years of age to prevent influenza virus infection.

The possible side effects of tamiflu are allergic manifestations (difficulty breathing, tightening of the throat, edema of the lips, tongue or face or rash). Less serious side effects, you can continue to use and tell your doctor if you have the following signs and symptoms: nausea, vomiting or diarrhea; stomachache; headache; dizzy; tiredness or any abnormalities especially uncomfortable Insomnia or cough or other respiratory symptoms.

The worry that Tamiflu is not strong enough to oppose a pandemic H5N1 is still in place. Tamiflu-resistant viruses can still be sensitive to other antiviral drugs such as Relenza (zanavir). So it is necessary to reserve both Tamflu and Relenza to prevent a pandemic from occurring. Viruses can mutate so you should not use too much Tamiflu; Some treated people have created mutated virus strains. Viruses that mutate are less likely to be infectious than wild viruses, so these viruses are not easily spread. While the mutated virus strain is sensitive to Relenza, there is no guarantee that Relenza will be effective against bird flu.

Is there a vaccine to protect people against H5N1? There are currently no vaccines that can protect people against the H5N1 virus. However, the efforts to create this vaccine are just beginning. Vaccine trials were conducted in April 2005 and are continuing.

DAO XUAN DUNG