Definition: “Influenza, an infectious illness caused by an influenza virus, is also known as Flu”. Flu is highly infectious (of a disease), transmitted from one person or organism to another, commonly regarded as a “contagious disease” through direct contact, and is generally spread by an infected person’s coughs and sneezes. While painful, the flu is rarely life-threatening. It happens globally and affects millions of people in all countries every year. By touching an infected human, for example, shaking hands, you may also catch influenza. Adults are infected 1-2 days before they show symptoms and up to 7 days after they become sick. This implies that before the individual comes to know that he or she is sick, the person may spread the influenza virus.
Types of Influenza
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It has three sub-types:
- Influenza A (Potentially serious disease, rapidly changing epidemics and pandemics).
- Influenza B (Less serious disease, more uniform epidemics, generally).
- Influenza C (Usually mild or asymptomatic, with limited effects on public health).
1. Influenza A and Influenza B: Influenza A and B viruses in the world are responsible for disease epidemics. Older people over 65 years of age and children below 18 months of age have the highest mortality rate.
2. Influenza C: The influenza virus type C is responsible for mild respiratory diseases and is not responsible for outbreaks.
- Agent: Type A Type B, Type C Influenza.
- Host Characteristics: Age, Prior Exposure, Immune response.
- Intervention: Isolate, Treat, Immunize, Nutrition.
- Environment: Climate, Population (Overcrowding).
- Caused due to the presence of influenza viruses. These viruses are classified within the family orthomyxoviridae.
- Animals and birds such as; swine, dogs, cats, horses, wild birds, etc. are a reservoir of infection.
- The secretions present in the respiratory tract of influenza are infectious especially nasopharyngeal secretions.
- It occurs in all ages and among both sexes.
- It affects individuals over 65 years of age, children under 18 months of age, patients with diabetes, heart disease, kidney or respiratory disorders. Attack rates are lower among adults.
- High Care Fatality Ratio (CFR) during an epidemic in high-risk cases.
- Season: The seasonal occurrence is striking; in the northern hemisphere, epidemics typically occur in the winter months. In India, however, summer epidemics have sometimes occurred.
- Overcrowding: Overcrowding increases infection transmission. In closed population groups, the attack rates are high.
Mode of Transmission
1. Direct contact transmission: It requires close physical contact between the source of the disease and the transmission from person to person to a susceptible host. The intermediate object is not involved.
2. Indirect contact transmission: Indirect transmission of touch implies that the agent is transmitted by implies of a non-living entity.
3. Droplet Transmission: In mucus droplets that move a short distance (less than 1 meter), microbes are distributed.
4. Airborne Transmission: Airborne transmission refers to pathogens carried over a distance greater than 1 meter by water droplets or dust.
Symptoms of Influenza
- High fever
- Runny or Stuffy Nose
- Sore throat
- Muscle pain
- In diagnosing It, a variety of tests can help. Its diagnostic tests available include; viral culture, serology, rapid antigen scanning, polymerase chain reaction (RT-PCR) reverse transcription, immunofluorescence assays, and rapid molecular assays.
- Virus is detected by the indirect fluorescent antibody technique and by serological examination.
Specific diagnostic test:
- Nasopharyngeal swab.
- Nasal wash, aspirate swab.
- Broncho Alveolar Lavage [BAL].
- Oropharyngeal swab.
- Combined nasopharyngeal or nasal swab with an oropharyngeal swab.
Prevention and Control of Influenza
- Respiratory Hygiene: When coughing and sneezing, cover the nose/mouth with a handkerchief/tissue paper, use and dispose of tissues to absorb respiratory secretions.
- Hand Hygiene: After interaction with respiratory secretions and infected products, hand washing with non-antimicrobial soap and water, alcohol-based hand rub, or antiseptic handwashing.
- Avoid overcrowded places.
- Use of Antiviral Drugs: Amantadine, Rimantidine, Zanamvir, Osletamivir, etc.
- Vaccines: Killed vaccine, live attenuated vaccines, and other vaccines like Recombinant vaccine.
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