Transcript Case Study - Cal State LA - Instructional Web Server

Case Study - Hantavirus
Group 6
Microbiology 401 Fall 2007
Chona Herrella, Saray Felix, Yanping Fan
Case Study
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61 year old healthy male
Patient resided in a house on four rural
acres
Two months prior to hospitalization, he
cleaned a mouse nest from a wood pile
Observed mice in the basement and
trapped two mice under the kitchen counters
Symptoms
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Vermont resident hospitalized for:
 Three episodes of chills, fever, nausea, vomiting and anorexia
Patient had clear lungs and chest radiographs
After admission in the hospital, patients health worsened:
 Respiratory failure
 Profound Hypoxemia
 Hypotension – required mechanical ventilation
 Fluid in the lungs – Acute Respiratory Distress Syndrome (ARDS)
 Disseminated Intravascular Coagulation and Renal Insufficiency
Family Bunyaviridae
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(-) ss RNA
Enveloped
3 gene segments (L, M, S;
some S genes are ambisense,
all other segments are (-) sense)
Three helical, spherical
nucleocapsids
Segmented genomes of Hantavirus
Glycoprotein G2
3’ to 5’ terminal ends
S Segment
M Segment
Capsid
Envelope
Glycoprotein G1
L Segment
Family Bunyaviridae
 All package their genomes together with the
necessary Replicase
 All have flexible nucleocapsids with helical symmetry.
 All have an envelope containing virally encoded
glycoprotein spikes that are involved in attachment
and penetration.
 All have genomes without a 5’ cap or a 3’ poly A tail
 Penetrates through cell-mediated endocytosis with
pH-dependent fusion
Sin nombre virus
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Our case was caused by one of five genera, the
Hantavirus also called the Sin nombre virus
Diagnosis
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CBC (will show elevated white blood count)
Platelet count (will be less than 150,000 and decreasing)
X-ray of the chest (may show material invading the lungs,
involving both lungs)
Liver enzymes (LDH will be elevated)
Serum albumin (levels will be decreased)
Hematocrit (will be increased, showing an increase in the
levels of red blood cells)
Serological indirect testing for hantavirus
• serologic identification of IgM and IgG antibodies to SNV
• immunofluorescence assay
How does Sin Nombre virus cause
Respiratory Distress?
HANTAVIRUS PULMONARY SYNDROME (HPS)
 Infection process:
 The virus attacks host endothelial cells
 The immunological mechanism of host attacks the
infected endothelial cells causing permeability of
pulmonary arteries and capillaries.
 Studies have shown an increase amount of Cytokineproducing cells (TNF- , IL-2, and IFN-γ) and CD8+ Tcells in the lungs
 Extravasation of fluids into the pleura cavity of the
lungs
 Results: shortness of breath
Radiologic Evolution of HPS
http://www.aafp.org/afp/20020915/1015.html
Cont’d
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In severe cases the ff may occur:
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Myocardia depression
resulting in Sinus Bradycardia - heart rate below 60 beats
per min
with subsequent electromechanical dissociation - may not
have pulse
ventricular tachycardia – increase in heart rate due to one
of the ventricles in the heart
Fibrillation – contraction of the cardiac muscle of the
ventricles in the heart is uncoordinated. Which then fails to
pump blood throughout the body causing unconsciousness
within seconds and even death.
How can we get infected?
Byproducts of mice that can infect humans through
Aerolisation:
Urine
Feces
Saliva
www.nsf.gov/news/mmg/mmg_disp.cfm?med_id=5854...
NOTE: One cannot be infected by another human!!!!
HPS Demographics
Vermont
Preventing Hantavirus Outbreak
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Do not need to isolate patients infected with
the virus! Why?
It cannot be transmitted from person to
person, only through aerolisation of byproducts of an infected mouse
 Instead, one would need the demographics of
the infected patients in order to…
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Outbreak Prevention
Outbreak prevention cont’d
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Need to locate mice population
infected with the hantavirus
Need to remove or contain the
population of infected mice
Need to inform the residents
near the infected location where
outbreak took place
Take preventive measures to
assure that mice do not come
into close contact with the
residents through:
Preventive Measures:
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Educating the population on how to
decontaminate possible infected areas (cabins,
garage, etc)
How to dispose of dead mice, waste materials and
decontamination tools used (call local state health
department)
Educate the population with the precautions
needed to take in order to prevent infection
Precautions to be used:
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Decontaminate infected (or possible
infected) areas:
Wear protective gear
Do not stir up rodent by-products (feces,
dried urine)
Do not come in contact with rodents even if
they do not show signs of infection
Do not invite rodents into your home
Other Hantavirus Diseases:
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Hemorrhagic Fever with Renal Syndrome (HFRS)
• A disease mainly found in Europe and Asia (Korea, China, East
Russia and Balkans)
• Can also be transmitted through byproducts of mice carrying the
disease (urine, feces and saliva)
• Initial symptoms:
• flushing of the face, inflammation or redness of the eyes, or a rash.
• Later symptoms:
• low blood pressure, acute shock, vascular leakage
• malfunctioning of the kidneys and hemorrhaging (due to low platelet
counts)
• Complete recovery can take weeks or months.
• The severity of the disease varies depending upon the location of
the virus causing the infection…
Other Hantavirus Diseases
cont’d:
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Hantavirus causing Hemorrhagic Fever with
Renal Syndrome (HFRS):
Hantaan virus
 Seoul virus
 Puumala virus
 Dobrava virus
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Hantavirus Demographics