The Case of the Big Bad Bug

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The Case of the Big Bad Bug16

• Jim Pointer, MD
• Alameda County EMS
• Medical Director

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The Call

• A south county resident calls 9-1-1 complaining
  of a 2 day history of fever (103), headache,
  maliaise, nausea, weakness, stiff neck, and a
  rash.

3
History

• The patient is a 74 year old male with a past
  history of CABG x 3 and prostate cancer.
• Current medications include
• Nitroglycerine
• Aspirin
• Proscar
• No history of foreign travel

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Field Assessment

• Primary survey WNL
• Vital signs
• B/P 152/97, PR 138, RR 22
• Temp 102.6 p.o.
• Secondary survey (pertinent findings)
• HEENT dry mucous membranes
• Lungs clear
• Skin warm/dry erythematous maculopapular rash
  on neck trunk
• Neuro confused, GCS 13 - 14

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Treatment

• IV normal saline 500ccs
• Glucose check 102 mg/dl
• Transport to Culex Memorial Hospital

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Hospital Course

• The patient tells the physician that he saw
  several dead Stellars Jays on his property 5-7
  days ago. When he picked them up he received
  several insect bites

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Hospital Exam

• Vital signs
• B/P 142/98, PR 126, RR 20
• Temp - 102.7 p.o.
• Pulse Ox - 98 RA
• Additional physical findings
• Mild nuchal rigidity

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Laboratory Findings

• CBC 11.1 K
• 86 lymphocytes, 10 PMNs, 2
  Basophils, 2 Eosinophils
• Na, K, HCO3, Cl-, BUN, creatinine, glucose
  WNL
• Cerebrospinal fluid
• Color clear, WBC 120 cells/mm3
• Protein 82 mg/dL (n 20 45)
• Glucose 78 mg/dL (n 50 80)

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West Nile Virus

• Ecology
• Enzootic cycle culcine mosquitoes and birds
• Corrids (crows, ravens, jays) are particularly
  susceptible
• Bridge vector mosquitoes in late summer
• Over 30 mosquito species responsible
• Mammals (humans, horses, ? deer)
  dead-end hosts
• Surveillance systems dead birds,
  sentinel chickens, ill horses

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West Nile Virus (cont.)

• First isolated in 1937
• First occurred in western hemisphere in New York
  in 1999
• About 400 deaths reported in the US to date
  about 9,000 cases reported for 2003
• Vaccine available for horses (1/3 of infected
  horses die)

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Transmission Cycle
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Virology

• Single stranded RNA virus
• Family Flaviviridae
• Genus Flavivirus
• Member of Japanese encephalitis virus
  serocomplex including
• Japanese encephalitis
• St. Louis encephalitis
• Murray Valley encephalitis
• Kunjin viris

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Geographic Distribution 2004
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Geographic Distribution Calif.
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Geographic Distribution horses
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Clinical Features

• Incubation period 3 14 days
• Probably lt 20 of those infected will develop
  clinical infection
• Febrille illness of sudden onset
• malaise, myalgias, anorexia
• nausea, vomiting
• Eye pain, headache
• Rash, lymphadenopathy

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Clinical Features (cont.)

• 1/150 infections result in meningitis/
  encephalitis
• Encephalitis is more common
• Advancing age most significant risk factor for
  neurologic disease
• Age 50 to 59 - 10x higher
• Age gt 80 - 43x higher
• Severe weakness in 50 of hospitalized patients
  in U.S.

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Table of Symptoms
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Outcome

• Death rates 4 14
• Much higher in older patients or those with
  diabetes or immunocompromised
• Morbidity
• Fatigue
• Memory loss
• Depression
• Difficulty walking

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Treatment

• Supportive
• Ribavirin and interferon effective in vitro
• No clinical trials

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Lab Findings

• WBC normal or elevated
• Occasional anemia
• Low sodium
• CSF
• WBC - 0 to 1782 cells/mm3
• Protein - elevated
• Glucose - normal

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Lab Findings (cont.)

• MRI meningeal or periventricular enhancement
• IgM
• most efficient diagnostic method (serum
  or CSF)
• Persistent for gt 6 months
• Present in other Flavivirus infections and
  in vaccinated persons

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Reporting

• Reportable disease
• Serum and CSF specimens must be submitted

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Prevention

• Reduce of mosquitoes
• Eliminate breeding sites
• Apply larvacides or approved pesticides
• Prevent mosquito bites
• Use DEET (not gt 50 adults/10 kids)
• Employ barrier methods

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(No Transcript)
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Pull out Bettypull out! I think you hit an
artery
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Reference

• Petersen LR, Marfin AA West Nile Virus A primer
  for the clinician, American Journal of Internal
  Medicine. 2002 137 E 173 - 179