Transcript Document

Viruses causing respiratory
infections. Influenza viruses.
Paramyxoviruses. Measles and
mumps viruses.
Vinnitsa National Pirogov Memorial Medical University /
Department of microbiology
Classification of an
Orthomyxoviridae
Family Orthomyxoviridae includes
three pathogenic for human
species:
 Influenza virus A
 Influenza virus B
 Influenza virus C
Influenza virus
Antigenic structure of influenza virus
Internal antigens (S-antigen)
1. Ribonucleoprotein (RNP)
2. M-protein from inner layer of envelope
External antigens (V-antigen)
1. Hemagglutinin (HA)
2. Neuraminidase (N)
Antigenic variation of influenza virus
 Antigenic variability may be of two
different types:
1. Antigenic drift
2. Antigenic shift
Epidemiology of the flu
 The source of infection may be:
1. Infected person
2. Wild and domestic birds
3. Domestic animals
 Characteristics of the viruses have caused the most
famous pandemics:
 In 1917-1919 “Spanish flu” was caused by A (H1N1)
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virus
In 1957 “Asian flu” was caused by A (H2N2) virus
In 1968 “Hong Kong flu” was caused by A/Hong Kong
(H3N2)
In 1977 “Red flu” was caused by A (H1N1)
From 1968 and 1977 pandemics both types (H1N1 and
H3N2) have been circulated together
 Endemic influenza annually in the US1
 5% to 20% of the population gets the flu
 More than 200,000 people are hospitalized from flu
complications
 About 36,000 people die from flu
 Avian Influenza, cumulative data2
 379 cases reported, 239 deaths (63%)
 2008: 28 cases / 22 deaths
 1http://www.cdc.gov/flu/keyfacts.htm
 2APR 08, WHO
Avian Influenza,
cumulative data2
379 cases reported,
239 deaths (63%)
2008: 28 cases / 22
deaths
Laboratory diagnostics
 Collected samples are nasal or throat swabs, nasal or
throat washing, sputum, nasal prints
 Rapid tests are based on the demonstration of the
virus antigens in the collected material. They include:
1. Direct immunofluorescence
2. Reversed indirect hemagglutination test (RIHA)
3. FLU OIA and QUICKVUE Influenza Test are based on
detection of the viral antigens with monoclonal
antibody
4. ZSTATFLU is based on detection of viral
neuraminidase with colored substrate of the enzyme
Laboratory diagnostics
 Microscopy
 Isolation of the virus (culture or virological method)
 Serology (serological method)
Laboratory diagnostics of the flu
Immunofluorescence
Virus inoculation into chicken
embryo
Specific prophylaxis
 Specific prophylaxis is immunization with subunit
influenza vaccines 3-4 weeks before predictable onset
of epidemic (Fluarix, Influvac, Vaxigrippe, Grippol and
others).
Paramyxoviruses
 Family Paramyxoviridae
 Subfamily Paramyxovirinae includes three
genera:
 Respirovirus (four serotypes of parainfluenza
viruses)
 Morbillivirus (measles virus)
 Rubulavirus (mumps virus)
 Subfamily Pneumovirinae contains one genus
Pneumovirus (respiratory syncytial virus)
Structure of a paramyxovirus
Antigenic structure and biological
features
Outer antigens: HN and F
Inner antigens: RNP and M-protein
Epidemiology and pathogenesity
Parainfluenza viruses cause croup (acute
laryngotracheo-bronchitis), laryngitis, brochiolitis
and pneumonia in children and a disease resembling
the common cold in adults. They are responsible for
50-80% of respiratory tract infections
Measles virus causes measles
Mumps virus causes mumps
The source of infection is an ill person
Paramyxoviruses are transmitted via respiratory
droplets (airborne diseases)
Maculopapular rash (measles)
Laboratory diagnostics
1. Rapid tests:
 Immunofluorescence test
 Cytoscopy
2. Culture method
3. Serological investigation
Treatment and prophylaxis
Prophylaxis is made by immunization with alive
attenuated vaccine
For current prophylaxis in pregnant women,
children with immunodeficiency anti-measles
and normal human immunoglobulin are used
Mumps: clinical findings and immunity
 Mumps is acute infectious disease commonly
affecting children and characterized by
nonsuppurative enlargement of parotid glands
Laboratory diagnostics
1. Virus isolation (culture method)
2. Serological tests
Prevention of mumps may be done with alive
attenuated vaccine
Current prophylaxis is possible with either alone
vaccine (active immunization) or normal human
immunoglobulin (passive immunization)
Parainfluenza virus
 Type 1 and type 2 cause croup ( acute
laryngotracheobronchitis) in children
 Type 3 cause tracheobronchitis, bronchiolitis and
pneumonia in children before 5 years.
 Type 4 provokes mild respiratory infections
Laboratory diagnosis is based on virus isolation from
throat and nasal swabs.
Serological tests with paired sera can confirm diagnosis
by 4-fold and greater rising of antibody titer