Influenza, commonly known as “the flu“, is an infectious disease affecting birds and mammal caused by RNA Virus.
The most common symptoms are fever, chills, sore throat, generalized muscle pain, headache, coughing and malaise (weakness, fatigue, tiredness). This is often diagnosed as “Common cold, Flu like illness or URTI and often treated by doctors with antibiotics.
Influenza is a more severe disease caused by a different type of virus. Influenza may produce nausea and vomiting in children. The symptoms are more common in the unrelated gastro-enteritis – inaccurately referred to as “stomach flu”
Flu can occasionally lead to pneumonia, either direct viral pneumonia or secondary bacterial pneumonia, even for persons who are usually very healthy.
Children and even adults get better with our without treatment but may relapses with a high fever because of secondary bacterial infection causing pneumonia. These patients usually present with dyspnea (trouble breathing) or known as Breathlessness.
Typically, influenza is transmitted through air (droplet infections when sneezing or coughing) or by direct contact with bird droppings, nasal secretions or through contact with contaminated surfaces.
Airborne aerosols have been thought to cause most infections, although which means of transmission is most important is not absolutely clear. Influenza viruses can be inactivated by sunlight but effect of disinfectants and detergents iis now controversial. Virus can be removed from hands using soap, frequent hand washing reduces the risk of infection
Seasonal epidemics (local spread of known organisumss) are common and so spread all over the world. Three to five million yearly cases of severe illness and about 250,000 to 500,000 yearly deaths, rising to millions in some pandemic. In 20th century three pandemics (new strains spreading worldwide) occurred, each caused by the appearance of new strains of the virus in humans, and killed tens of millions of people.
Often, new influenza strains appear when an existing flu virus spreads to humans from another animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concern of a new influenza pandemic after it emerged in Asia in the 1990s, but this has not spread easily between people.
In April 2009 normal flu strain evolved that combined genes from human, pig, and bird flu. This was called “Swine flu” (H5N1) emerged in Mexico, the United States, and several other nations.
The World Health Organization officially declared the outbreak to be a pandemic on 11 June 2009. The WHO’s declaration of a pandemic. The death rate was rapid but lower than normal flu epidemic.
The most common human vaccine is the trivalent (TIV) that contains purified and inactivated antigens from three viral strains. Typically, this vaccine includes material from two Influenza A, B and it has very low reactivity. Vaccine manufactured for one year may be ineffective in the following year, since the influenza virus evolves rapidly, and new strains quickly replace the older ones. Antivirus drugs used are not as effective as they claim to be and is only said to help reduce viral shedding and reduce hospital admission and spread. The publications about effectiveness of these drugs was criticized and said to be sponsored by drug companies
Signs and symptoms
Fever (68–86%), Cough (84–98%), Nasal congestion (68–91%). All three findings are less common in people over 60 years of age.
Symptoms of influenza, with fever and cough the most common symptoms.mApproximately 33% of people with influenza are asymptomatic.
Onset of symptoms can be sudden, one to two days after infection. The first common symptoms are chills, fever with body temperatures ranging from 38–39 °C (approximately 100–103 °F). Patients are so ill, and are confined to bed for several days, with aches and pains throughout their body. Pain said to be worse in their backs and legs. Symptoms of influenza may include:
Fever, Chills and rigours (feeling hot and cold), Cough, Body aches, Fatigue, Head ache, Watery eyes, Redish face, eyes, nose and troat.
Children may suffer from tummy (abdominal) pain, diarrhea and vomiting (Often wrongly labeled as “Tummy flu”)
It can be difficult to distinguish between the common cold (caused by numerous virus) and and influenza in the early stages of these infections. Flu often start with high fever with a sudden onset and extreme fatigue.
Diarrhea is not normally a symptom of influenza in adults, although it has been seen in some human cases of the Swine Flu, or Bird Flu.
Since said to be effective in treating influenza if given early. The symptoms listed above, the combinations of fever with cough, sore throat and/or nasal congestion can improve diagnostic accuracy.
Influenza can occasionally go on to relapse of symptoms resulting in secondary bacterial pneumonia. The obvious symptom is trouble breathing. In addition, if a child (or presumably an adult) seems to be getting better and then relapses with a high fever, that is a danger sign since this relapse can be bacterial pneumonia.