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Plate 85. Viral Diseases of the Respiratory System. Respiratory System. The respiratory system is responsible for oxygenating the blood and removing waste carbon dioxide from the blood. Respiratory System. Alveoli are the final branches of the “respiratory tree”
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Plate 85 Viral Diseases of the Respiratory System
Respiratory System • The respiratory system is responsible for oxygenating the blood and removing waste carbon dioxide from the blood
Respiratory System • Alveoli are the final branches of the “respiratory tree” • Allow gases to exchange between the lungs and the blood • Tissue between alveoli and capillaries is very thin – allowing for easy gas exchange
Viral Diseases of the Respiratory System • Most viral diseases do not directly kill the host organism • Rather, the viruses destroy cells within the respiratory system, making them susceptible to bacterial infection • Staphylococci • Streptococci
Influenza • Human influenza viruses (helical, RNA viruses) • Type A • Causes seasonal epidemics • Found in ducks, chickens, pigs, whales, horses, and seals • Categorized into subtypes based upon surface proteins • Hemagglutinin (H) • 16 variations • Neuraminidase (N) • 9 variations • Current strains include H1N1 and H3N2 • Type B • Causes seasonal epidemics • Only found in humans • Type C • Causes mild respiratory illness
Novel H1N1 – “Swine Flu” • Caused by “antigenic shift” – a major change in the virus with a new combination of hemagglutinin and neuraminidase proteins • So different from other influenza viruses that most people don’t have immunity to it • Pigs can be infected with human and avian influenza viruses, and they can mix • It’s thought that “Swine Flu” has genes mostly from a human virus, but surface proteins from an avian virus
Influenza Symptoms • Fever • Cough • Sore throat • Runny or stuffy nose • Muscle or body aches • Headaches • Fatigue
Influenza Complications • Bacterial pneumonia • Ear infections • Sinus infections
Influenza Vaccinations • CDC recommends “universal” flu vaccinations • Especially the following groups: • Pregnant women • Children younger than 5 • People 50+ years old
Influenza Transmission • Spread through respiratory droplets • Also possible to get by touching a surface that has the virus on it, then touching your eyes, mouth, or nose • May be able to infect others 1 day before symptoms appear and 5-7 days after becoming sick
Severe Acute Respiratory Syndrome (SARS) • Caused by a coronavirus (SARS-associated coronavirus) • Coronaviruses have been linked pneumonia • The virus may survive in the environment for several days
SARS Symptoms • High fever (>100.4° F) • Headache • Discomfort • Body aches • Diarrhea • Pneumonia
SARS Transmission • Spread through respiratory droplets • Spread through touching a contaminated object, then touching your mouth, nose, or eyes • “Close contact” – living with someone with SARS, having direct contact with body fluids from a patient • Incubation period is between 2-7 days, but the disease is only contagious while symptoms are present
Global SARS Outbreak (2003) • Between November 2002 – July 2003 • 8,098 people became infected worldwide • 774 died • 8 people in U.S. were confirmed to have SARS, 0 deaths
Common Cold • More than 200 viruses cause the “common cold” • Rhinoviruses and adenoviruses are the most common
Common Cold - Symptoms • Sneezing • Stuffy or runny nose • Sore throat • Coughing • Mild headache • Mild body aches
Common Cold – Runny Nose • Nose makes clean mucus when infected to wash the virus from the sinuses • Immune cells begin to fight the virus, changing the mucus to a white or yellow color • As bacteria in nose grow back, they may change the mucus to a greenish color