Patho Exam 2

Influenza Pathophysiology

  • Virus that causes influenza:

    • Belongs to the Orthomyxoviridae family.

    • Characterized by a segmented, single-stranded RNA genome.

  • Influenza A:

    • Capable of infecting multiple species including avian and mammalian.

    • Divided based on two surface glycoproteins:

    • Hemagglutinin (HA):

      • Functions as an attachment protein allowing viral entry into epithelial cells of the respiratory tract.

    • Neuraminidase (NA):

      • Involved in viral replication from the infected cell.

  • Antigenic Shift:

    • Major genetic rearrangement of either HA or NA proteins.

    • Can lead to significant outbreaks like epidemics or pandemics.

  • Antigenic Drift:

    • Minor genetic mutations accumulating rapidly.

    • Allows the virus to evade partially immune populations relying on pre-existing antibodies.

  • Influenza B & C:

    • These influenza viruses undergo antigenic changes less frequently than Influenza A.

  • Contagiousness:

    • Influenza is more contagious than bacterial infections.

    • Transmission occurs via inhalation of droplet nuclei, with young children being the most likely to be infected.

  • Incubation Period:

    • Ranges from 1 to 3 days, with 2 days being the average.

    • Patients are contagious starting from day 1 through approximately 8-9 days after symptom onset.

    • Viral shedding: occurs for 6 to 7 days.

  • Types of Influenza Infections:

    • Uncomplicated upper respiratory infection (rhinotracheitis):

    • Results in symptoms such as nasal discharge and sore throat.

    • Viral Pneumonia:

    • Can develop, especially in vulnerable populations such as older adults.

    • Secondary Bacterial Infection:

    • A bacterial infection can follow viral infection, notably pneumonia.

  • Initial Infection Effects:

    • Virus targets and kills mucous-secreting and ciliated epithelial cells in the upper airway.

    • Leads to gaps between basal cells allowing fluid escape, causing rhinorrhea (runny nose).

    • If infection spreads to lower respiratory tract, severe shedding of bronchial and alveolar cells occurs, compromising respiratory function.

  • Secondary Bacterial Pathogens:

    • Common pathogens causing secondary pneumonia include:

    • Streptococcus pneumoniae

    • Staphylococcus aureus

    • Haemophilus influenzae

    • Moraxella catarrhalis

    • These infections typically exhibit less tachypnea and discomfort compared to primary viral pneumonia.

  • Influenza-Related Deaths:

    • Result from pneumonia, exacerbations of existing conditions, and complications arising in chronic diseases.

  • Reye Syndrome:

    • A rare but significant complication, particularly in children taking aspirin, characterized by fatty liver and encephalitis.

Signs/Symptoms

  • Early Stages:

    • Abrupt onset of:

    • Fever and chills

    • Rigors and malaise

    • Headache

    • Muscle aches

    • Profuse, watery nasal discharge

    • Nonproductive cough

    • Sore throat

  • Rapid Onset:

    • One of the hallmarks of influenza is rapid onset of profound malaise, sometimes noted within 1-2 minutes of illness.

  • Duration of Symptoms:

    • Uncomplicated rhinotracheitis peaks between days 3 to 5, disappearing by days 7 to 10.

    • Influenza C symptoms resemble those of the common cold.

  • Viral Pneumonia Effects:

    • Most frequently affects older adults or individuals with pre-existing cardiopulmonary conditions.

    • Clinical course may lead to rapid progression, causing hypoxemia and death within a few days of onset.

Pneumococcal Pneumonia Pathophysiology

  • Pathogens:

    • Streptococcus pneumoniae is the most common cause of bacterial pneumonia.

    • Characteristics include: gram-positive diplococcus with a polysaccharide capsule which enhances virulence by preventing phagocytosis.

  • Immune Response:

    • Absence of antibodies leads to reliance on the reticuloendothelial system for clearance, involving macrophages, particularly those in the spleen, playing a critical role.

  • Initial Pathogenesis:

    • Pathogenic process begins with colonization of respiratory mucosa, whereby healthy individuals can be carriers without showing symptoms, aiding in transmission.

  • Stages of Pneumonia Pathology:

    • The pathological process can be divided into four stages:

    1. Edema: Alveoli fill with fluid containing pathogens.

    2. Red Hepatization: Massive leukocyte and erythrocyte infiltration leads to congestion, resembling liver tissue.

    3. Gray Hepatization: Marked by macrophage action on cellular debris, resulting in respiratory compromise.

    4. Resolution: Restoration of normal lung function as alveolar exudates are cleared.

  • Complications:

    • Secondary complications may include sinusitis, otitis media, and potentially severe outcomes like bacterial pneumonia following viral pneumonia.

    • Symptoms include a recurrence of fever, shaking chills, and pleuritic chest pain.

Treatment/Medications

  • Initial Management:

    • Rest and hydration are essential.

    • Monitor fever and manage symptoms with analgesics and cough medications.

  • Medications within 24-48 hours:

    • Baloxavir (Xofluza)

    • Zanamivir (Relenza)

    • Peramivir (Rapivab)

    • Oseltamivir (Tamiflu)

  • Vaccination Recommendations:

    • Vaccination against influenza is recommended for all individuals over 6 months of age, excluding those allergic to eggs or with acute febrile illness.

Additional Info

  • Avian Influenza:

    • Infectious strains include H5, H7, and H9 affecting birds and occasionally humans.

  • Swine Flu:

    • Notable for the H1N1 strain of Influenza A which emerged as a global concern.

Renal Disorders

Protein-Energy Malnutrition Pathophysiology

  • Conditions:

    • Common among infants and children, particularly those in low-income countries due to inadequate protein and calorie intake.

    • Divided into:

    1. Marasmus: Protein and calorie deficiency.

    2. Kwashiorkor: Severe protein deficiency.

  • Symptoms of Marasmus:

    • Diminished muscle mass, subcutaneous fat loss, and stunted growth.

    • Leads to dehydration, infection susceptibility, and growth failure.

  • Symptoms of Kwashiorkor:

    • Characterized by edema, discolored hair, and desquamating skin.

    • Presents with anemia and malabsorption of macronutrients.

  • Nutrition During Illness:

    • Malnutrition commonly secondary to hypermetabolic states from trauma or illness, leading to kwashiorkor-like symptoms due to increased protein requirements.

  • Diagnosis and Treatments:

    • Requires a multimodal approach focusing on hydration, gradual calorie increase, and addressing infections while avoiding additional complications.