Plate 85
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Transcript of Plate 85
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
Peak Months of Influenza Activity
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
• http://www.flu.gov/video/psa/stay_healthy_america.html
Severe Acute Respiratory Syndrome (SARS)
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