Reddy: Vector Borne and Zoonotic Infections/ Bioterrorism Flashcards
New Viral Diseases (since 1976):
- Ebola Fever
- Adult T Cell Leukemia (HTLV)
- AIDS
- Hepatitis C
- Hantavirus
- HHV8
- SARS
Re-Emerging Viruses (severe epidemics):
- Yellow Fever
- Dengue Fever
- Measles Virus
- West Nile Virus
- St.Louis Encephalitis Virus
- Monkeypox Virus
- Pandemic flu
Weapons of Bioterrorism:
Small pox virus
Factors Contributing to Emergence of Infectious Diseases:
Ecological/Environmental Changes: for example, weather anomalies and Hantvirus pulmonary syndrome
Behavior: for example, sexual behavior/IV drug use and AIDS
Human Demographics: for example, urbanization/increased population density and Dengue Fever
Technology and Industry: for example, blood tissue products for medical use and AIDS, HBV and HCV
Possible Causes of Emerging Diseases:
- Infected human host or reservoir
- Human-transported vertebrae host (legal or illegal)
- Storm-transported vertebrae host (bird)
- Intentional induction (terrorist event)
Last Case in US:
Two Reserves for Smallpox:
Last Case in US: 1949; eradicated from the world in 1977 (stop vaccinating for it in the US in 1972)
Two Reserves for Smallpox:
o CDC (Atlanta, US)
o Institute of Virus Preparations (Moscow, Russia)
Smallpox
Genus:
Structure:
Genome:
o Genus: Orthopoxvirus
o Structure: brick shaped, enveloped
o Genome: dsDNA; replicates in cytoplasm
Smallpox
Disease Symptoms:
o Fever and chills o Headache o Malaise o Sore throat o Cough o Backache o Painful skin lesions (centrifugal rash that scabs and scars)
Smallpox
Incubation Period:
Transmission:
Incubation Period: 10-14 days (for both variola major and minor)
Transmission: respiratory route (stable in environment); also direct contact
Smallpox
Types of Disease
Based on mortality:
Variola major (~30% mortality) Variola minor (~1% mortality)
Flat-type smallpox:
Flat-type smallpox: RARE; slow evolution of flat, soft, focal skin lesions (high mortality, especially in unvaccinated)
Hemorrhagic-type smallpox:
Hemorrhagic-type smallpox: RARE; extensive mucosal hemorrhage and intense toxemia (die before lesions appear)
Smallpox
Virus Genus Replication Incubation Distribution Growth of Eruptions Pustules Scab Formation Scab Separation Scaring
Variola Orthopoxvirus Cytoplasm 7-17 days Face, palms and soles Synchronous Firm and deep 10-14 days after rash onset 14-28 days after rash onset Yes
Chickenpox
Virus Genus Replication Incubation Distribution Growth of Eruptions Pustules Scab Formation Scab Separation Scaring
VZV Herpesvirus Nucleus 14-21 days Trunk Different Stages Soft and superficial 4-7 days after rash onset <14 days after rash onset No (normally)
Smallpox
Diagnostic Tests:
Skin Samples:
• Electron microscopy (EM)
• Immunoflurorescence
• PCR
Smallpox
Vaccination:
Post-Exposure Therapy:
Pre-Exposure Preventive Vaccine: uses a special needle (bifurcated)
• No longer part of vaccine regimen in the US (singe 1972)
• US government has enough smallpox vaccine to effectively respond to a smallpox outbreak
Post-Exposure Therapy:
• Supportive therapy
• Antibiotics for secondary infection
• Antivirals against it are under investigation currently
Monkeypox
Similar signs and symptoms to:
Originated:
People got sick after having contact with:
Transmission:
Similar signs and symptoms to smallpox: mortality rate was higher BEFORE the eradication of smallpox
Originated in West and Central Africa in the 1970s: first time reported in the US was in 2003
People got sick after having contact with prairie dogs infected with monkeypox
Monkeypox
Transmission: direct contact with infected wild and exotic mammalian pets
- Person-to-person transmission is rare
Transmission: direct contact with infected wild and exotic mammalian pets
o Person-to-person transmission is rare
Monkeypox
Incubation period:
Clinical Features:
Prevention:
Incubation period: 10-14 days
Clinical Features: hard to differentiate from smallpox
- Monkeypox produces a generalized pustular rash with smaller lesions, fever and minor toxemia
Prevention: CDC recommends smallpox vaccination to protect people exposed to monkeypox virus
Arboviruses
Transmission:
Genome:
Transmission: anthropod vectors (main vectors are flies and ticks)
Genome: RNA
Arboviruses: (3)
Togaviridae
Flaviviridae
Bunyaviridae
Togaviridae: (3)
Togaviridae: EEE, Sindbis, Rubella virus
Flaviviridae: (6)
Flaviviridae: WNV**, DV, YFV, SLE, JE, Hepatitis C Virus
Bunyaviridae: (1)
Bunyaviridae: Hanta virus
Hantaviruses
First outbreak in US:
Transmission:
First outbreak in US: 1993 (SW US)
Transmission: rodent borne (deer mouse); aerosolization of rodent excreta
- No person-to-person transmission
Hantaviruses
Genome:
Structure:
Viral Entry:
- Genome: -ssRNA; replication in cytoplasm
- Structure: enveloped
- Viral Entry: cellular receptors and subsequent endocytosis
Hantaviruses
Disease Symptoms:
Early Symptoms:
Late Symptoms:
Disease Symptoms: causes respiratory distress syndrome (Hantavirus Pulmonary Syndrome)
Early Symptoms: fever, chills, headaches, SOB, N/V/D, dizziness, abdominal/back/chest pain
Late Symptoms: cough, sweats, SOB
Hantaviruses
Diagnosis:
- Virus isolation
- RT-PCR
- Immunohistological technique
Hantaviruses
Treatment:
Prevention:
Treatment: no treatment or cure (need to provide support through severe respiratory distress)
Prevention: control mice in and outside of house
Ebola Virus
Family:
Genus:
Family: Filoviridae
Genus: Filovirus
Ebola Virus
Transmission:
Transmission: close contact and dirty needles (contact with blood or secretions)
Ebola Virus
Viral Structure:
Helical nucleocapsid –ssRNA genome Composed of 7 polypeptides: - Nucleoprotein - Glycoprotein - Polymerase - 4 other undesignated proteins
Ebola Virus
Reservoir:
Viral Entry:
Reservoir: no know reservoir that harbors he virus has been identified
Viral Entry: mechanism unknown
Ebola Virus
Treatment:
No pre- or post-exposure prophylaxis
No antiviral drug has been show to be effective
Ebola Virus
Clinical Features:
Lesions found:
Some strains cause:
Clinical Features: causes a severe hemorrhagic fever
Lesions found in liver, spleen and kidney
Some strains cause massive destruction of the liver (Ebola Sudan, Zaire and Reston- only in monkeys)
Pandemic Flu
Definition:
Flu Basics:
Definition: a disease that can erupt globally
Flu Basics:
- Only 4 know Influenza A subtypes circulating among humans (H1N1, H1N2, H3N2, H7N2)
- H5N1 is an avian flu that has affected a few humans, but person to person spread is limited (concern arises due to H5N1’s ability to mutate, with the possibility that one day it could evolve into a strain easily transmitted from person to person)
Seasonal Flu:
- Follow seasonal pattern (winter in temperature climates)
- Usually some immunity from the previous exposure (healthy adults not at risk for serious complications)
o Very young, elderly, and those with underlying health conditions are - Vaccine available and antivirals as well
- Low mortality rate
- Manageable impact on domestic and world economy
Pandemic Flu:
- Rare occurrence
- People have no previous exposure and little/no pre-existing immunity
- Even healthy people at increased risk for serious complications
- Vaccines would probably not be available at the beginning of the pandemic; antivirals would run low
- High mortality rate
- Drastic impact on domestic and world economy
Avian Flu (H5N1)
- Pandemic starts when the virus meets these 3 criteria:
o New influenza subtype
o Able to infect humans and cause serious illness
o Able to spread easily among humans - H5N1 only fits the first two criteria (would have to undergo reassortment or adaptive mutation to be able to be spread person to person)
- No vaccine; resistant to Amantidine and Ramantidine; need to use Oseltamivir and Zanamavir
Severe Acute Respiratory Syndrome (SARS)
First outbreak in:
Family:
Genus:
First outbreak in 2003 in Hong Kong: then spread worldwide
Family: Coronoaviridae
Genus: Coronavirus
Severe Acute Respiratory Syndrome (SARS)
Viral proteins identified: (6)
o Polymerase protein o Spike protein (S) o Small membrane protein (E) o Membrane protein (M) o Nucleocapsid protein (N)
Severe Acute Respiratory Syndrome (SARS)
Incubation Period:
Symptoms:
Incubation Period: 2-7 days
Symptoms:
o High fever and chills
o Headache, discomfort and body aches
o Mild respiratory symptoms at outset (some)
Severe Acute Respiratory Syndrome (SARS)
Diagnosis:
Treatment:
Diagnosis:
o Detection of serum Ab to SARS-CoV
o Isolation in cell culture of SARS-CoV from clinical specimen and PCR confirmation
o Detect SARS-CoV RNA by RT-PCR
Treatment: none at this time