Influenza Virus Jay Patel Cristian Santos Carol Vong

Background Information Family: Orthomyxoviridae Genus: Influenza Baltimore Calssification: Class 5 Single Stranded RNA viruses Influenza has 3 strains: A,B,C. Influenza virions structures can appear either spherical or tubular The envelope contains two glycoproteins, hemagglutinin (HA) and neuraminidase (NA) proteins while having an inner lining of matrix (M1) and membrane (M2) proteins.

What is that? Is it a Cold, a Flu, an Allergen?

The Unsuspecting Host In late December, a 22-year-old man suddenly experienced headache, myalgia (muscle pain), malaise (discomfort/ “being out of it”), dry cough, and fever. He basically felt lousy. After a couple of days, he had a sore throat, his cough had worsened, he started to feel nauseated, and he began vomiting. Several of his family members had experienced similar symptoms during the previous 2 weeks. The flu season usually peaks between January and February, about the time the patient is showing symptoms.

1) In addition to influenza, what other agents could cause similar symptoms? Differential Diagnoses: Influenza initially establishes a local upper respiratory tract infection. The symptoms of the influenza virus are fever, aches, pains, weakness, headache, dry cough, sore throat, and watery discharge from nose. There are many other agents that can cause similar symptoms. Rhinovirus & Coronavirus has symptoms that are eerily similar to influenza symptoms, often the case of mistaken diagnosis. Bacterial infections such as strep throat, bronchitis, and pneumonia can cause similar inflammation and pains. Gastroenteritis(stomach flu) can also exhibit similar symptoms.

2) How would the diagnosis of Influenza be confirmed? Laboratory diagnosis is usually the best method for confirmation of influenza virus infection. Rapid antigen assays can detect and distinguish influenza A and B. A real time polymerase chain reaction with generic influenza primers are utilized as part of the rapid antigen assay. An enzyme immunoassays or immunofluorescence to detect viral antigen in cells, secretions, or cell cultures. Immunofluorescent or inhibition of hemagglutination (envelope glycoprotein) with a specific antibody.

3) Oseltamivir (Tamiflu) is effective against influenza. What is its mechanism of action ? Will it be effective for this patient? For uninfected family members or contacts? Oseltamivir is a neuraminidase inhibitor which competitively inhibits the binding of viral neuraminidase to sialic acid, causing cells to clump as they exit the cell inactivating them. If the Tamiflu pill is given orally within 48 hours of infection it is effective. A NA inhibitor is effective against both influenza A and B and therefore effective for the patient, since influenza C is quite rare. Since the patient has been having symptoms for 48+ hours the drug is not effective. 1 Though a NSAID or Acetaminophen would be a better option to control the symptoms as opposed to the virus. Oseltamivir will be effective for uninfected family members because it can prevent the drug is intended to prevent the spread of the virus. 1 1:

Vector and Transmission Vector: Major Vector of transmission to humans are other humans But the initial infection is from contact with either an avian or swine source Transmission: Direct contact with infected individuals; Contact with contaminated objects (called fomites, such as toys, doorknobs); Inhalation of virus-laden aerosols

4) When was the patient contagious, and how was the virus transmitted. According to the Center for Disease Control, most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. 2 The flu is spread primarily by the following: The virus being aerosolized. Direct contact between individuals Being left on inanimate objects, aka Fomites i.e. Table, Chair, Pen, Cellphone, etc… 2:

5)What family members were at greatest risk for serious disease, and why? Elderly Immuno-compromised i.e. Pregnant women Family members are at risk for serious disease, especially the ones with underlying cardiac or respiratory problems such as smokers and those who suffer from asthma. 3 More than 90% of deaths occur in patients over 65 years of age. 3: Davis MM, Taubert K, Benin AL, et al. Influenza vaccination as secondary prevention for cardiovascular diseased. A science advisory from the American Heart Association/American College of Cardiology.Circulation2006; 114:

6) Why is influenza so difficult to control, even when there is a national vaccination program? Airborne virus spreads every time a person breathes, speaks, and coughs i.e. Aerosols, contaminated surfaces Best way to control infection is through immunization Natural Immunity and Vaccine It can easily spread in high populated places Virus’ ability to generate new strains through mutation and reassortment Produce new virions of influenza A Antigenic drift & antigenic shift Anamnestic antibody response

Questions? References info/spread.htm /S Davis MM, Taubert K, Benin AL, et al. Influenza vaccination as secondary prevention for cardiovascular diseased. A science advisory from the American Heart Association/American College of Cardiology.Circulation2006; 114: s1553