Vinnitsa National Pirogov Memorial Medical University / Department of microbiology
Viruses causing respiratory infections. Influenza viruses.
Paramyxoviruses. Measles and mumps viruses.
Classification of an Orthomyxoviridae
Family Orthomyxoviridae includes three pathogenic for human species:
Influenza virus AInfluenza virus BInfluenza virus C
Influenza virus
Antigenic structure of influenza virusInternal 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 virusAntigenic variability may be of two
different types:
1.Antigenic drift
2.Antigenic shift
Epidemiology of the fluThe source of infection may be:
1.Infected person
2.Wild and domestic birds
3.Domestic animalsCharacteristics of the viruses have caused the most
famous pandemics:In 1917-1919 “Spanish flu” was caused by A (H1N1)
virusIn 1957 “Asian flu” was caused by A (H2N2) virusIn 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
1.
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 fluAvian Influenza, cumulative data2
379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths
1http://www.cdc.gov/flu/keyfacts.htm2APR 08, WHO
Avian Influenza, cumulative data2
379 cases reported, 239 deaths (63%) 2008: 28 cases / 22 deaths
Laboratory diagnosticsCollected samples are nasal or throat swabs, nasal or
throat washing, sputum, nasal printsRapid 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 diagnosticsMicroscopy
Isolation of the virus (culture or virological method)
Serology (serological method)
Laboratory diagnostics of the fluImmunofluorescence Virus inoculation into chicken
embryo
Specific prophylaxisSpecific prophylaxis is immunization with subunit
influenza vaccines 3-4 weeks before predictable onset of epidemic (Fluarix, Influvac, Vaxigrippe, Grippol and others).
ParamyxovirusesFamily ParamyxoviridaeSubfamily 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 pathogenesityParainfluenza 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 diagnostics1. 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 diagnostics1. 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 virusType 1 and type 2 cause croup ( acute
laryngotracheobronchitis) in childrenType 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
Top Related