Viral Hemorrhagic Fevers. Objectives Describe the natural geographic distribution of VHF and scenarios suggestive of bioterrorism Describe the clinical.

Viral Hemorrhagic Fevers

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


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


Differential Diagnosis

• Fever in a traveler– Malaria– Typhoid fever

• Other Differential Diagnoses– Meningococcemia– Rickettsial infection– Leptospirosis– Acute leukemia– Idiopathic or thrombotic thrombocytopenic purpura


Hospital Course

• Hospital Day #4– Despite empiric antibiotics including

antimalarials, pt develops acute respiratory distress syndrome (ARDS)

– Required intubation


Differential Diagnosis

• Fever in a traveler– Malaria

– Typhoid fever

– Yellow fever

– Lassa fever


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


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


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


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


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


Clinical Presentation• Initial:

– High grade fever, headache, myalgias, fatigue, abdominal pain

• Advanced disease:– Bleeding– Maculopapular rash– Exudative Pharyngitis (Lassa)– Meningoencephalitis– Jaundice






Transmission

• Direct contact with blood/body fluids/cadavers

• Aerosol spray (droplet v. airborne)• Sexual transmission• Percutaneous• Bite of infected tick or mosquito


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


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


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


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


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


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


This completes the current presentation.

Viral Hemorrhagic Fevers. Objectives Describe the natural geographic distribution of VHF and scenarios suggestive of bioterrorism Describe the clinical.

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