viral hemorrhagic fevers. objectives describe the natural geographic distribution of vhf and...
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Viral Hemorrhagic Fevers
Objectives
• Describe the natural geographic distribution of VHF and scenarios suggestive of bioterrorism
• Describe the clinical manifestations of VHF in general
• List exposure classification of contact for cases of VHF
• Describe infection control precautions for personnel caring for patients with VHF
• List therapeutic options for patients with VHF
Viral Hemorrhagic Fevers
Case Presentation• 38 yo business man returned from West Africa via
London, ill for 3 days– new onset fever– chills– severe sore throat– diarrhea– back pain
• PE: T103.6 BP 90/60, alert– Skin with diffuse ecchymosis and a maculopapular rash
on the extremities
MMWR 2004;53(38):891-897
Viral Hemorrhagic Fevers
Differential Diagnosis
• Fever in a traveler– Malaria– Typhoid fever
• Other Differential Diagnoses– Meningococcemia– Rickettsial infection– Leptospirosis– Acute leukemia– Idiopathic or thrombotic thrombocytopenic purpura
Viral Hemorrhagic Fevers
Hospital Course
• Hospital Day #4– Despite empiric antibiotics including
antimalarials, pt develops acute respiratory distress syndrome (ARDS)
– Required intubation
Viral Hemorrhagic Fevers
Differential Diagnosis
• Fever in a traveler– Malaria
– Typhoid fever
– Yellow fever
– Lassa fever
Viral Hemorrhagic Fevers
Hospital Course
• Hospital Day #4– Despite empiric antibiotics including antimalarials,
pt develops ARDS– Required intubation
• Hospital Day #5– Local and state health departments notified– Investigational new drug (IND) protocol to
administer IV ribavirin– Patient died before administration of any drug
Viral Hemorrhagic Fevers
Diagnosis
• Clinical and post-mortem specimens sent to CDC
• Lassa virus confirmed– Serum antigen detection– Immunohistochemical staining liver tissue– Virus isolation in cell culture– RT-PCR sequencing of virus
Viral Hemorrhagic Fevers
FAMILY/GEOGRAPHY AGENT CASE-FATALITY
Filoviridae
Sub-saharan Africa
Ebola
Marburg
50-75%
25%
Arenaviridae
West Africa (Lassa)
South America, California (Whitewater)
Old World: Lassa
New World: Junin,
Machupo, Guanarito Sabia, Whitewater arroyo
Lassa:1-2% (up to 25% in hospitalized pts)
30% for New World
Bunyaviridae
Sub-saharan Africa
Egypt, Yemen
SW US (Hantavirus)
Phlebovirus: Rift Valley
Nairovirus: Crimean Congo
Hantavirus: Sin Nombre
Rift Valley: <1% overall
50% in hemorrhagic
Flaviviridae
Sub-saharan Africa
Central Asia
Yellow fever
Dengue
Omsk
Kyasanur
Yellow Fever: 5-7% overall
50% in hemorrhagic
www.cidrap.umn.edu/index.html accessed 2/4/05
Viral Hemorrhagic Fevers
Epidemiology• Incubation period
– 2 days to 3 weeks for most VHF– Lassa fever: 21 days
• Endemic regions– Sub-saharan Africa
• Lassa fever causes 100-300,000 infections and 5,000 deaths each year
• 20 imported cases reported worldwide• Human to human transmission has occured
– South America
Viral Hemorrhagic Fevers
Why do VHFs make good Bioweapons?
• Disseminate through aerosols• Low infectious dose• High morbidity and mortality• Cause fear and panic in the public• No effective vaccine• Available and can be produced in large quantity• Research on weaponization has been conducted
Viral Hemorrhagic Fevers
Clinical Presentation• Initial:
– High grade fever, headache, myalgias, fatigue, abdominal pain
• Advanced disease:– Bleeding– Maculopapular rash– Exudative Pharyngitis (Lassa)– Meningoencephalitis– Jaundice
Viral Hemorrhagic Fevers
Transmission
• Direct contact with blood/body fluids/cadavers
• Aerosol spray (droplet v. airborne)• Sexual transmission• Percutaneous• Bite of infected tick or mosquito
Viral Hemorrhagic Fevers
Infection Control• Lassa Fever in New Jersey Investigation:
– 5 high risk contacts (wife, kids, visitor)– 183 low risk contacts
• 9 other family members• 139 HCW at hospital: 42 labworkers, 32 RN, 11 MD• 16 labworkers in Virginia and California• 19 passengers on flight from London to Newark
• No additional cases occurred
Viral Hemorrhagic Fevers
Infection ControlRisk Category Description SurveillanceCasual Contacts Remote contact with
index case (eg, stayed in same hotel)
VHF not spread by casual contact, no
special surveillance
Close Contacts More than casual (eg, living with contact, caretaker, shook
hands with contact)
Place under surveillance once index case
confirmed
High-Risk Contacts Mucous membrane contact (eg, kissing, or
penetrating injury involving contact with
index case’s blood such as needlestick)
Place under surveillance as soon as consider diagnosis of VHF in
index case
CDC Update: management of patients with suspected VHF-United States MMWR 1995;44:475-79
Viral Hemorrhagic Fevers
VHF Personal Protective Equipment• Airborne and Contact isolation for patients with respiratory symptoms
– N-95 or PAPR mask– Negative pressure isolation– Gloves– Gown– Fitted eye protection and shoe covers if going to be exposed to splash body fluids
• Droplet and Contact isolation for patients without respiratory symptoms– Surgical mask– Gloves– Gown– Fitted eye protection and shoe covers if going to be exposed to splash body fluids
• Environmental surfaces– Cleaned with hospital approved disinfectant– Linen incinerated, autoclaved, double-bagged for wash
Viral Hemorrhagic Fevers
Treatment
• Supportive care:– Fluid and electrolyte management– Hemodynamic monitoring– Ventilation and/or dialysis support– Steroids for adrenal crisis– Anticoagulants, IM injections, ASA,
NSAIDS are contraindicated– Treat secondary bacterial infections
Viral Hemorrhagic Fevers
Treatment• Manage severe bleeding complications
– Cryoprecipitate (concentrated clotting factors)– Platelets– Fresh Frozen Plasma– Heparin for DIC
• Ribavirin in vitro activity vs.– Lassa fever– New World Hemorrhagic fevers– Rift Valley Fever– No evidence to support use in Filovirus or Flavivirus
infections
Viral Hemorrhagic Fevers
Vaccination
• Argentine and Bolivian HF– PASSIVE IMMUNIZATION
• Treat with convalescent serum containing neutralizing antibody or immune globulin
• Yellow Fever– ACTIVE IMMUNIZATION
• Travelers to Africa and South America
P. Jahrling, Chapter 29, Medical Aspects of Clinical and Biological Warfare; p591-602
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