case study - hantavirus group 6 microbiology 401 fall 2007 chona herrella, saray felix, yanping fan
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Case Study - Hantavirus
Group 6
Microbiology 401 Fall 2007
Chona Herrella, Saray Felix, Yanping Fan
Case Study
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
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
(-) 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
Capsid
Glycoprotein G1
L Segment
3’ to 5’ terminal ends
M Segment
S Segment
Envelope
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
Our case was caused by one of five genera, the Hantavirus also called the Sin nombre virus
Diagnosis
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 Cytokine-producing cells (TNF- , IL-2, and IFN-γ) and CD8+ T-cells 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
In severe cases the ff may occur: 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?
Urine
Feces
Saliva
Byproducts of mice that can infect humans through Aerolisation:
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
Do not need to isolate patients infected with the virus! Why?It cannot be transmitted from person to
person, only through aerolisation of by-products of an infected mouse
Instead, one would need the demographics of the infected patients in order to…
Outbreak Prevention
Outbreak prevention cont’d
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:
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:
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: 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:
Hantavirus causing Hemorrhagic Fever with Renal Syndrome (HFRS):Hantaan virusSeoul virusPuumala virusDobrava virus
Hantavirus Demographics