Aswin Ppt.pptx

Influenza Virus &

Its Prevention and Control ASWINI KUMAR DAS BSc IN Biotechnology TRIDENT ACADEMY OF CREATIVE TECHNOLOGY ROLL NO-1602010190510022 SESSION:-2016-2019

INTRODUCTION:• Influenza, commonly called "the flu," is an illness caused by RNA viruses of the family Orthomyxoviridae the influenza viruses that infect the respiratory tract of many animals, birds, and humans. • In some countries, seasonal influenza affects annually up to 40% of the population and 500 million people die from it worldwide every year.

• Flu symptoms may begin suddenly and might be severe include fever, dry cough, sore throat, headache, extreme tiredness, and body aches.

WHAT IS ORTHOMYXOVIRIDAE? • The Orthomyxoviridae are a family of RNA viruses that includes five genera:Influenzavirus A, Influenzavirus B, Influenzavirus C, Isavirus and Thogotovirus. A sixth has recently been described. The first three genera contain viruses that cause influenza in vertebrates, including birds (see also avian influenza), humans, and other mammals. Isaviruses infectsalmon; thogotoviruses infect vertebrates and invertebrates, such as mosquitoes and sea lice.

Three types of influenza viruses had been in circulation in humans:

 Influenza A  Influenza B  Influenza C • There are 15 different H subtypes and 9 different N subtypes allowing for 135 potential different viral strains. Only 3 haemagglutinins (H1, H2, H3) and 2 neuraminidases (N1, N2) are found in influenza A viruses ordinarily infecting humans.Influenza type A viruses undergo two kinds of changes: 1-Antigenic drift, 2-Antigenic shift. •

Influenza B is also highly contagious and can have dangerous effects on your health in more severe cases. However, this form can only be spread from human to human. Type B influenza can cause seasonal outbreaks and can be transferred throughout the year.

• Influenza type C is relatively stable compared with types A and B. It infects humans, is less common, causes a very mild respiratory illness or no symptoms and is not reported to cause epidemics

EPIDEMIOLOGY:• Influenza is a highly infectious viral disease which can occur as a pandemic, epidemic, outbreak and in form of sporadic cases. A majority of human infections are caused by either type A or B influenza viruses. • Type A has been associated with widespread epidemics and pandemics, while type B has been infrequently implicated in regional epidemics. Influenza type C infections cause only a mild respiratory illness • Yearly influenza epidemics can affect all populations,Annual attack rate is estimated at 5–10% in adults and 20–30% in children.In temperate climates seasonal epidemics of the virus occur mainly during the winter time. • The long-term epidemiologic success of influenza viruses is primarily due to antigenic variation that takes place in the two surface glycoproteins of the virus, the HA and NA.Variation in influenza A and B viruses is caused by the accumulation of point mutations in the HA and NA genes.

MODE OF TRANSMISSION :• Influenza virus may be transmitted among humans in three ways: (1) by direct contact with infected individuals, (2) by contact with contaminated objects like(fomites,such as toys,doorknobs, (3) by inhalation of virus-laden aerosols. • Nasal secretions that contain virus particles are responsible for transmission by direct contact or via contaminated objects. An infected individual most often touches the nose or conjunctiva, thus placing virus on the hand. Any ensuing contact (for example, shaking hands) can transfer the virus to another person, who will then infect themselves by simply touching their eyes or nose. • The virus transmission also happens upon touching other objects with contaminated hands. Researchers have shown that up to 60% of objects from homes and day care facilities were shown to harbor influenza viral RNA.

Cause and Risk Factors for Influenza:• In most cases, people infected with the flu recover without medical treatment within 2 weeks. • Patients who have :heart, lung (e.g., asthma), or kidney problems; diabetes; cancer; HIV/AIDS; or other chronic conditions • Have a higher risk for developing complications (e.g., pneumonia) from the flu. Young children under 2 years of age and people over the age of 65 also are at increased risk. • Other people who are at increased risk for developing flu complications include the following:  Children who are on long-term aspirin therapy  Patients who have medical conditions that can compromise breathing (e.g., spinal cord injury, seizure disorders, nerve or muscle disease, brain injury). • Patients who live in a long-term care facility (e.g., nursing home) or who were hospitalized during the previous year • Women who are pregnant during flu season. • Also other factors can contribute to the spread of AI viruses including globalization and international trade (legally and illegally), marketing practices (live bird markets), farming practices and the presence of the viruses in wild birds.

CLINICAL SIGNS OF THE INFLUENZA: Fever (usually 100 F-103 F in adults and often even higher in children)  Cough,  Sore throat,  Runny or stuffy nose,  Headache,  Muscle aches,  Extreme fatigue • Nausea, vomiting, diarrhea, and ear infection (otitis media) also may occur with the flu. These symptoms are more common in children.

DIAGNOSIS:Virus isolation: Nasal swabs, throat swabs,nasopharyngeal aspirates and sputum are the specimens usually submitted to the laboratory.Nasopharyngeal secretions are the best specimens for obtaining large quantities of virus–infected cells. Serology testing: Some of serological methods such as agar gel immunodiffusion tests can be used to detect antibodies to these antigens. • Paired Sera A sero diagnosis of influenza A or B can be made by the examination of two serum specimens from a patient. • Hemagglutination inhibition tests have also been employed in routine diagnostic serology

 Rapid antigen testing:- Commercial rapid influenza diagnostic tests are

available that can detect influenza viruses within 15 minutes. Different tests can detect 1) only influenza A viruses; 2) both influenza A and B viruses, but not distinguish between the two types; or 3) both influenza A and B and distinguish between the two.  Biopsy or autopsy tissue section: Polymerase chain reaction (PCR):- molecular tests detect viral genetic material in respiratory samples like a nasal or throat swab and are the most sensitive for influenza virus. These tests may be ordered to diagnose  influenza A infection, especially in those who are seriously ill (hospitalized), and to help track influenza outbreaks. Some false negatives can occur with this method. Some molecular tests can distinguish between A and B virusand between different types of influenza A virus.  Immunofluorescence assays

 Rapid molecular assays

CONTROL AND PREVENTION: The illness and death caused by seasonal influenza can be prevented by getting an annual influenza vaccination (the ‘flu jab’). Seasonal vaccination is especially recommended for those people who are in an at-risk group.  If you develop flu symptoms you should follow basic hygiene practices to avoid spreading the disease to other people, including: • Get vaccinated every Fall/Winter. Annual flu vaccination is the best way to prevent flu in our community. • Clean hands often with soap and water or use alcohol-based hand rub. • Don’t share personal items like toothbrushes or drinks. • Cover your mouth and nose with a tissue (or shirt sleeve) when sneezing, coughing, or nose blowing. • Clean frequently touched items and surfaces with soap and water.  People who do not regularly come into contact with birds are not at high risk for contracting avian influenza. It is extremely important to have early detection and warning systems andprevention measures in place as part of an effective strategy for AI.

Treatment and Management: There are mainly two types of drugs are mainly use.

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1) Neuraminidase inhibitors (oseltamivir, peramivir, and zanamivir) 2) M2 inhibitors (amantidine, rimantidine)

 Generally for future avian influenza threats, the WHO suggests a 3 phase:• Phase 1: Pre-pandemic;Reduce opportunities for human infection and Strengthen the early warning system. • Phase 2: Emergence of a pandemic virus; Contain or delay spread at the source. • Phase3: Pandemic declared and spreading internationally, Reduce morbidity, mortality, and social disruption and Conduct research to guide response measures.