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EPIDEMIOLOGY OF RESPIRATORY TRACT INFECTIONS

EPIDEMIOLOGY OF RESPIRATORY TRACT INFECTIONS. R espiratory tract is usually divided into three segments. The Upper Respiratory tract: This includes the nose, paranasal sinuses, and throat. The Respiratory Airways: This includes the trachea, bronchi, and bronchioles.

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EPIDEMIOLOGY OF RESPIRATORY TRACT INFECTIONS

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  1. EPIDEMIOLOGY OF RESPIRATORY TRACT INFECTIONS

  2. Respiratory tract is usually divided into three segments • The Upper Respiratory tract: This includes the nose, paranasal sinuses, and throat. • The Respiratory Airways: This includes the trachea, bronchi, and bronchioles. • The Lungs: This includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and the alveoli.

  3. The following defense mechanisms in the alveoli protect the parenchymal cells from invasion by microorganisms • Alveolar macrophages (the most important) • Complement components • Alveolar lining fluid containing surfactant, phospholipids, neutral lipids, IgG, IgE, IgA, secretory IgA, certain complement components, Factor B, and other unidentified agents that maybe important in activation of alveolar macrophages • B cells, T cells, and null cells that can elicit a localized immune response to infection • Lymphoid tissue associated with the lungs

  4. Mechanisms used to avoid phagocytosis • Capsule production. (S. pneumoniae, H. influenza, B. anthracis, N. meningitidis, K. pneumoniae) • Toxin production. These toxins could include cytotoxins, leukocidins, and exotoxins. (examples; S. aureus produces leukocidins and cytotoxins. P. aeruginosa produces exotoxin A which destroys cells much like the diphtheria toxin does.) • Being too large to phagocytize. Parasites and fungi are often too large for the phagocyte to engulf. • Replication inside cells. Viruses and Chlamydia sp. are obligate intracellular parasites that replicate inside the cells of the lung avoiding the phagocyte. • Mimicry. Some parasites produce surface proteins which are very similar to host proteins or acquire host proteins and appear to the phagocyte as self. Some bacteria produce proteins that cause host proteins to bind to their surfaces (ex. protein A/Staphylcoccus aureus)

  5. Mechanisms used to survive in the phagocyte • Inhibition of lysosome fusion with the phagosome. (Toxoplasma gondii, Aspergillus sp., Chlamydia psittaci) • Escape from the phagosome. (Mycobacterium leprae, Trypanosoma cruzi, Influenza virus escapes the phagolysosome) • Resistance to killing and digestion in the phagolysosome. (Mycobacterium tuberculosis, Nocardia sp., Yersinia pestis) • Growth in the phagocytic cell. (M. tuberculosis, Legionella pneumophila, Cytomegalovirus) • Entry into the phagocyte other than by phagocytosis. Some organisms avoid destruction by getting into the phagocyte's cytoplasm. No phagosome-lysosome fusion occurs and the organisms can survive in the phagocyte. (Toxoplasma gondii, some enveloped viruses)

  6. Nonbacterial Agents that Cause Upper Respiratory Tract Infections of Man

  7. Flu and other respiratory tract infections

  8. Main nosologic forms • Influenza; • Parainfluenza; • RSV infections; • rhinovirus infections; • adenovirus infections.

  9. (Flu, influenza) - Acute viral illness with the direct mechanism of transmission of agent, distribution epidemic and pandemic; it is characterized by the infection of respiratory tracts, expressed intoxication, fever and moderate catarrhal phenomena.

  10. Key facts • Influenza is an acute viral infection that spreads easily from person to person. • Influenza circulates worldwide and can affect anybody in any age group. • Influenza causes annual epidemics that peak during winter in temperate regions. • Influenza is a serious public health problem that causes severe illnesses and deaths for higher risk populations. • An epidemic can take an economic toll through lost workforce productivity, and strain health services. • Vaccination is the most effective way to prevent infection.

  11. Flu agents–RNA-containing virions, size varying from 80 to 120 nm

  12. Different viral antigens of influenza A: 1918 A.D– H1N1; 1957A.D– H2N2; 1968A.D– H3N2; 1977A.D– H3N2 andH1N1.

  13. INFLUENZA VIRUS FORMULA: А/Singapore/1/57/H2N2 А/Honkong/1/68/H3N2 А/Victoria/35/72/H3N2 A/Texas/36/91/H1N1

  14. SOURCES OF INFECTION: • Healthy person in the latent period; • Patient during whole period • Disease lasting -7 days • Recovery– it is proved that in individuals a virus can be conserved up to 14-15 days • Birds.

  15. Infectious agent: H5N1, H7N7, H9N2 Epidemiology: • zoonotic • source of infection – poultry • mechanism of transmission – droplet?, fecal-oral? contact? • receptivity: mostly children Clinic: Flu-like symptoms: fever, sensitivity to cold, headache, pain in muscles and throat symptoms of eyes infection pneumonia

  16. History: in 1997 in to Hong Kong, virus H5N1 (18 people became ill, 6 died); in 1999 in to Hong Kong, virus H9N2 (became ill 2 children); in 2003 in to Hong Kong, virus H5N1 and H9N2 (became ill 3 persons, a 1 man died); in 2003 in Netherlands the virus H7N7 (89 people became ill, a 1 person died); in 2004 – flash of bird flu H5N1 among people in China, Thailand, Vietnam (35 persons died). Features of virus of bird flu 2004: The virus became more virulent, that testifies to his mutation The virus overcame an inter-specific barrier from birds to the man, however while there are no proofs of that an exciter is passed straight from a man to the man (all sick people had the direct contact with the infected birds) The virus will strike children mainly the source of exciter and ways of distribution of virus are not certain, that does a situation with distribution of virus not by practically controlled one measures on prevention to distribution – complete elimination all total number of birds of livestock

  17. Classification of flu (J10) Serologictypes of virus: A (H1N1), (H2N2), (H3N2), B, C. Clinical forms: typical, atypical (afebrile, acatarrhal, hyper-acute). Degree of severity: mild, moderate, severe, very severe. Complication: pneumonia, otitis, sinusitis, tonsillitis, encephalitis, meningoencephalitis, pyelonephritis, pyelocystitis, cholangitis and others.

  18. Clinical differences of flu and other ARI

  19. Differential diagnosis: • tonsillitis; • ornitosis; • measles; • enterovirous illness; • typhoid; • viral hepatitis; • pneumonia; • inflammation of additional cavities of nose.

  20. Treatment • amantadine • rimantadine • Zanamivir (Relenza) • oseltamivir (Tamiflu) • ribavirin

  21. WHO recommends annual vaccination for (in order of priority) • nursing-home residents (the elderly or disabled) • elderly individuals • people with chronic medical conditions • other groups such as pregnant women, health care workers, those with essential functions in society, as well as children from ages six months to two years.

  22. Influenza vaccines are available in two forms: • an intramuscular preparation containing formalin-inactivated virus and purified surface antigen • an intranasal spray containing live attenuated viruses

  23. Vaccines: • The “Vaxigrip” firms of Paster Mark • “Fluorix” firms SmithClyayn Bichem • “Influvac” firms Solvey Farma • Influenza vaccine “Influvac”: components A/Sydney/455/97/H3N3, A/Beijing/263/95/H1N1 and B/Beijing/184/93. • It is intended for adults children. Enter intramuscular or deeply hypodermic. A protective effect is achieved in 10 days after introduction. Proceeds during 1 year.

  24. This preliminary negative stained transmission electron micrograph depicts some of the ultrastructural morphology of the A/CA/4/09 swine flu virus. Courtesy of CDC/ C. S. Goldsmith and A. Balish.

  25. Phase 6 criteria: In addition to the criteria defined in Phase 5, the same virus has caused sustained community-level outbreaks in at least one other country in another WHO region. Courtesy of the WHO.

  26. Adenovirus

  27. Conjunctivitis duringadenoviral infections:

  28. Pharyngo-conjunctivit is fever

  29. Treatment: • Bed regimen • milk-vegetable vitamin diet • inhalations with addition in the aerosol of lemon acid 1:1000 or juice of lemon, boric acid 1:100 • reflex-therapy and laser-therapy • antiviral preparations: remantadin, leucocytic interferon, amixin, cycloferon, amizon

  30. Indication for antibiotic therapy • Very severe flu (hyper toxic form with the phenomena of encephalitis, beginning from pneumonia) • flu in children the first 2 years of life, pregnant, very weakened, persons senile and old age • bacterial complications • accompanying chronic diseases

  31. Seasonal measures Increasing the resistance of persons, reflexotherapy, UV-rays Inductors of interferon secretion adaptogens (extract eleoterococa, tincture arali, gin-sing) Urgent measures Antiviral drugs Immunostimulators ointment of oxoline Leukocytic interferon Anti-influenza immunoglobulin Prophylaxis of flu and other ARI:

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