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Influenza. Causative Agent Orthomyxovirus Influenza A virus Infulenza B virus SS RNA virus 8 linear segments Enveloped with spikes H spike N spikes. Signs and symptoms Sudden high fever, pharyngitis, congestion, dry cough, headache and myalgia Acute symptoms decline within a week
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Influenza • Causative Agent • Orthomyxovirus • Influenza A virus • Infulenza B virus • SS RNA virus • 8 linear segments • Enveloped with spikes • H spike • N spikes
Signs and symptoms • Sudden high fever, pharyngitis, congestion, dry cough, headache and myalgia • Acute symptoms decline within a week • Cough, fatigue and generalized weakness may persist
Acquired through respiratory droplets • Attaches via hemagglutinin spikes • Induces phagocytosis and replicates inside cell
Mature viruses bud from host cell • Infected cells die and slough off • Destroys muco-ciliary escalator • Host immunity quickly controls viral spread
New strains due to hemagglutinin and neuraminidase mutations • Antigenic drift and antigenic shift • Avian flu (H5N1) • Swine flu (H1N1)
Epidemiology • Outbreaks occur every year • About 200,000 cases with up to 40,000 deaths • Pandemics have higher than normal morbidity • 1918-19 infected ½ the world population with 40 million deaths
Critical Swine Flu prevention tip: Don't DO this!
Prevention • Vaccine • New vaccine required every year • Treatment • Antiviral medications • amantidine and rimantidine resistance common • Inhaled zanamivir mist or oral oseltamivir must be taken with in 48 hours • No aspirin for children!
Respiratory Syncytial Virus Infection • Most common childhood respiratory disease • Leading respiratory killer of infants • Pathogen • Respiratory syncytial virus (RSV) • Enveloped, -ssRNA Paramyxovirus
Signs and symptoms • Fever, runny nose, and coughing • Wheezing and difficulty breathing may occur • Dusky skin tone • Leading cause of bronchiolitis in children under one • Some children develop croup • May lead to pneumonia if alveoli become involved
Epidemiology • Transmission occurs via respiratory droplet • Highly contagious • Syncytia help viruses evade immune system • Great risk of secondary infection
Prevention • No vaccine • Aseptic technique • Isolation of infected individuals • Treatment • Typically only supportive care • Ribavirin in extreme cases • No Aspirin!
Pneumocystis Pneumonia (PCP) • Causative Agent • Pneumocystis jiroveci • Opportunistic fungus • Obligate parasite • Normal respiratory flora for many
Signs and Symptoms: • Difficulty breathing; mild anemia; hypoxia; and fever • Non-productive cough in some cases • In rare cases, extra pulmonary lesions develop in lymph nodes, spleen, liver and bone marrow
Acquired through respiratory droplets • In healthy individuals usually no symptoms • Life long immunity is conferred • Some may remain carriers for life • Fungus multiplies rapidly in immunocompromised patients and extensively colonizes lungs • Causes substantial damage
Epidemiology • Worldwide distribution • 75% of healthy children exposed by age five • Based on presence of antibodies • Disease limited to immunocompromised individuals • One of the diagnostic diseases of AIDS
Prevention • Virtually impossible due to ubiquitous nature • Treatment • oral or IV TMP-SMX (combination of trimethoprim and sulfamethoxazole)