Download epidemiology of respiratory tract infections

EPIDEMIOLOGY OF
RESPIRATORY TRACT
INFECTIONS
Respiratory tract is usually divided
into three segments
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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.
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
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)
Mechanisms used to survive in the phagocyte
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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)
Nonbacterial Agents that Cause Upper Respiratory
Tract Infections of Man
Agents
Human Serotypes
Nucleic
Date of
Acid Types Discovery
Myxoviruses
Influenza
A, B, C
RNA
Parainfluenza
Respiratory
Syncytial Virus
Coronaviruses
1, 2, 3, 4
RNA
19331949
1953
1 (maybe 2)
RNA
1956
1
RNA
1965
RNA
1960s
RNA
1948
RNA
1948
RNA
1950s
DNA
1953
DNA
RNA
+ 1944
Picornaviruses
Rhinoviruses- most > 100 types
common cause.
24 (perhaps only A21 causes respiratory
Coxsackie virus A
illnesses)
6 (perhaps only B4, B5 cause respiratory
Coxsackie virus B
illnesses)
31 (perhaps only types 11, 20, 25 cause
Echoviruses
respiratory illnesses)
34 (types 1, 2, 3, 5, 7, 14, 21 are
Adenoviruses
responsible for respiratory illnesses)
Mycoplasma
1
pneumoniae
Flu and other
respiratory tract
infections
Main nosologic forms
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Influenza;
Parainfluenza;
RSV infections;
rhinovirus infections;
adenovirus infections.
(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.
Key facts
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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.
Flu agents–RNA-containing
virions, size varying from 80 to
120 nm
Different viral antigens of influenza A:
1918 A.D– H1N1;
1957A.D– H2N2;
1968A.D– H3N2;
1977A.D– H3N2 and H1N1.
INFLUENZA VIRUS FORMULA:
А/Singapore/1/57/H2N2
А/Honkong/1/68/H3N2
А/Victoria/35/72/H3N2
A/Texas/36/91/H1N1
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.
Infectious agent: H5N1, H7N7, H9N2
Epidemiology:
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zoonotic
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source of infection – poultry
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mechanism of transmission – droplet?, fecal-oral?
contact?
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receptivity: mostly children
Clinic:
Flu-like symptoms:
fever, sensitivity to cold, headache, pain in muscles
and throat
symptoms of eyes infection
pneumonia
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
Classification of flu (J10)
Serologic types 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.
Clinical differences of flu and other ARI
Disease
Beginning
Body
Temperature
Intoxicatio
n
Damage of respiratory
pathways
Other damages
Often
Rare
Trachitis
Bronchitis
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Rhinopharyngitis,
trachitis
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Kerato-conjuctivitis,
lymphoadenopathy,
hepato-splenomegaly.
Influenza (flu)
Acute
Febrile (3-5
days)
Developed
Para-influenza
Progressive,
rarely acute
Sub-febrile (till 2
weeks)
Immeasura
ble
Laryngitis
Progressive,
acute
Febrile (may
present > 5
days, minimum
5 days)
Mild
Pharyngitis,
rhinitis
Pneumonia
Mild
Bronchiolitis
Rhinopharyngitis,
laryngitis,
bronchitis,
pneumonia
Absent
Rhinitis,
serous
secretions
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Adenoviral
infection
Respiratory
synctal viral
infection
Rhinoviral
infection
Acute and
progressive
Sub-febrile,
rarely high (1-2
weeks)
Acute
Normal or subfebrile (1-3 days)
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Differential diagnosis:
tonsillitis;
ornitosis;
measles;
enterovirous illness;
typhoid;
viral hepatitis;
pneumonia;
inflammation of additional cavities of nose.
Treatment
amantadine
 rimantadine
 Zanamivir (Relenza)
 oseltamivir (Tamiflu)
 ribavirin
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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.
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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
Vaccines
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:
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.
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.
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.
Adenovirus
Conjunctivitis during adenoviral
infections:
Pharyngo-conjunctivit is fever
Treatment:
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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
Indication for antibiotic
therapy
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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
Prophylaxis of flu and other ARI:
Seasonal
measures
Increasing the resistance
of persons,
reflexotherapy, UV-rays
 Inductors of interferon
secretion
 adaptogens (extract
eleoterococa, tincture
arali, gin-sing)
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Urgent measures
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Antiviral drugs
Immunostimulators
ointment of oxoline
Leukocytic interferon
Anti-influenza
immunoglobulin