Clinical Case 1

1
Clinical Case 1

• Virus Group 11

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Patient

• Female, 26 yrs,
• single
• college student
• good health history
• no recurring diseases

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History

• On February 9, 2003, the above patient visited
  her chiropractor because she was developing a
  cold, and thought that a treatment might help
  reduce the severity of symptoms. Since she was an
  otherwise healthy patient, her chiropractor
  concurred with her prognosis. Two days later, the
  patient was sitting in class at the university,
  when she began to perspire profusely (fever) and
  to develop a severe headache. By the time the
  class was over, she was becoming very weak
  (malaise). With great difficulty, she drove home
  and went to bed. Her symptoms became worse during
  the course of the next 24 hrs with alternating
  periods of fever and chills. The next day, she
  was very sick with frequent coughing and pain in
  the chest. She managed to get an appointment at
  the University Clinic. The physician on duty
  recorded the following

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Symptoms

• fever 103 F
• chills
• pharyngeal inflammation sore throat
• respiratory congestion
• coryza/rhinorrea
• myalgia and malaise
• Crackling respiratory sounds

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Presumptive Diagnosis
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Laboratory

• Blood Sample sent to lab
• CBC
• leucopenia
• Serology
• Nasopharyngeal swab positive for group A
  orthomyovirus
• Serum exhibited a low titer of IgM against H2N2,
  type A orthomyxovirus
• Radiology
• No pulmonary consolidation

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Confirmed Diagnosis

• Influenza
• Type A

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Nature of the Organism

• Orthomyxoviruses
• Three serotypes, A,B, C
• based on matrix protein and nuceleoprotein
• neg sense segmented RNA( 8 segments),
• Serogroup A is responsible for most epidemic
• subtyped by envelope glycoprotein
• Hemagglutinin and Neuramidase antigens
• Genetic instability based upon mutation and
  recombination
• Type A, Human Orthomyxoviruses exhibit four
  hemagglutinins and two Neuramidase antigenic
  variants

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Pathogenesis

• Necrosis of the respiratory epithelium down to
  basal layer.
• Predilection for secondary bacterial involvement
• Course of the Disease
• Incubation period 1-4 days
• Viral shedding begins 24 hrs before symptoms
• Acute symptoms last 3-5 days
• Recovery based upon preexisting IgA and
  interferon
• Detectable antibody requires one week

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Influenza Complications

• Bacterial pneumonia
• Streptococcus pneumoniae
• Haemophilus influenzae
• Staphylococcus aureus
• others
• Reyes Syndrome
• Viral Pneumonia
• Influenza virus

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Epidemiology

• Person-to-person, direct, respiratory droplet
• Person-to-person, indirect, hands-fomites
• Antigenic nomenclature
• A/Hong Kong/3/68/H3N2
• Genetic shift
• Only type A serotypes exhibit antigenic shift
• increases population susceptibility and gives
  rise to epidemics.
• Due to genetic reassortment between mammal and
  birds strains
• Genetic drift
• Slight year to year antigenic changes due to
  mutation
• All three serotypes exhibit antigenic drift

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Influenza Pandemics

• 1918 HswH1
• 1947 A/FM/47/H1N1
• 1957 A/Singapore/57/H2N2
• 1968 A/Hong Kong/68/H3N2
• 1977 A/USSR/77/H1N1
• 1979 A/Bankok/79/H3N2
• 1989 A/Beijing/89/H3N2
• 1991 A/ Texa/91/H1N1

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Epidemiology of Pandemics

• All mammalian influenza viruses come from the
  avian influenza reservoir
• Based on RNA nucleotide sequence analysis
• All 15 HA variants are found in birds
• All nine NA variants are found in birds
• Viruses are not virulent in ducks, and are
  replicated in the GI
• Transmission to other animals is fecal -oral
• Only H1, H2, H3, H5 have been found in humans,
  Only N1 and N2
• H5 was never seen in humans before 1997
• Most reassortment between avian and human strains
  occurs in other mammals
• Most studies point to swine
• Exception may be H5N1

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Influenza Control

• Trivalent Vaccine
• inactive virus grown in chick embryos
• contains the two most recent type A strains, and
  one type B
• Neutralizing antibody against HA is protective
• Chemophylaxis
• amatadine or rimantadine
• Tamaflu?

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Influenza Control

• 2008 2009 Vaccine Composition
• Inactivated
• A/Brisbane/59/2007/H1N1-like
• A/Brisbane/10/2007/H3N2-like
• B/Florida/4/2006 - like

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Bird Flu

• Strains H5 H15
• Current Strain in Question
• A/avian/06/2003/H5N1

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Review

• Slide series on history of influenza epidemics