Biology Forums - Study Force

Patricia was called at work by a woman at the local daycare center. She told Patricia to come and pick up her son because he was not feeling well. Her son, 3 -year-old Marshall, had been feeling tired and achy when he woke up.
 
  While at daycare, his cheeks had become red and he was warm to touch. He did not want to play with his friends, and by the time Patricia arrived, he was crying. Later that afternoon, Marshall's condition worsened. He had fever, chills, a sore throat, runny nose, and a dry hacking cough. Suspecting Marshall had influenza, Patricia wrapped him up and took him to the community health care clinic.
 
  Why did Marshall's presentation lead Patricia to think he had influenza and not a cold? Why is it important to medically evaluate and diagnose a potential influenza infection?
 
  Describe the pathophysiology of the influenza virus. Outline the properties of influenza A antigens that allow them to exert their effects in the host.
 
  Marshall may be at risk at contracting secondary bacterial pneumonia. Why is this so? Explain why cyanosis may be a feature associated with pneumonia.

Influenza is characterized by a rapid onset of symptoms, particularly malaise. The common cold has a less aggressive onset with the initial appearance of nasal sinus irritation and excessive nasal secretions.
A proper investigation prevents the unwarranted use of antibiotics in a symptomatic patient. The reporting of influenza to public health authorities also contributes to the accurate monitoring of contagious illness within a population.

The influenza A virus damages the epithelial cells of the respiratory tract. They undergo necrosis and shed away to leave gaps between underlying basal cells. Extracellular fluid escapes through the basal membrane and contributes to fluid accumulation in the respiratory passages. Damaged ciliated cells are unable to move mucous within the airways, so mucous accumulation and congestion become an additional component to the infection.
Surface antigen HA facilitates the movement of the influenza A virus into the epithelial cells of the respiratory tract. The NA glycoprotein promotes viral replication and release from the host cell.

Viruses damage the protective mucous membranes in the nasopharynx. Because they also encourage mucous secretions, macrophage activity on pneumococci is inhibited while bacterial adhesion to the epithelium is enhanced. Pneumonia is a condition that causes inflammation of the alveoli. Cyanosis occurs as a result of the decrease in gas exchange through the inflamed alveolar membrane and subsequent decline in hemoglobin saturation.