Emerging Viruses

Question 1

What percentage of human morbidity and mortality derive from infectious disease?

Answer 1

25%

Question 2

Factors contributing to the emergence of new virus disease

Answer 2

• Increased population and population density
• Increased travel
• Changes in social behavior
• Changes in environment
• Changes in industry/technology
• Changes in microorganisms (mutation)

Question 3

Changes in demographics - Population growth

Answer 3

World population reached 6 billion on Oct 11, 2000

300 million in US on Oct 17, 2006

Question 4

Production and distribution of _____ ______ broadened the distribution of HIV/AIDS

Answer 4

blood products

Question 5

____ and ____ are clear examples where travel was an important facilitator of disease spread

Answer 5

SARS; HIV

Question 6

Changes in behavior

Answer 6

• Promiscuous sex
• Intravenous drug use
• Increased antibiotic/antiviral use
• Increased use of day care

Question 7

Changes in the environment

Answer 7

Climate change
Population movement into new territories
Habitat destruction

Question 8

Changes in the virus

Answer 8

• Mutation of surface molecules
• Mutation to antigenic difference so prior immunity is no longer effective
• Mutation to make it more pathogenic
• Mutation to antiviral resistance
• Change due to reassortment of segmented genomes

Question 9

Hantavirus - characterized by:

Answer 9

Fever
Hemorrhage
5-10% mortality
Headache
Acute renal failure

Question 10

Hantavirus in four corners area of US
Disease:
Emergence:
Host:

Answer 10

Disease: Pulmonary syndrome, pulmonary edema, shock, death
Emergence: due to High rainfall; plentiful food, increased mouse population
Host: deer mouse

Question 11

Number of cases of Hantavirus pulmonary syndrome
2012 cases:
Fatality rate:
Last noted outbreak:

Answer 11

2012 cases: 29
Fatality rate: 30-50%
Last noted outbreak: Yosemite Park

Question 12

Arbovirus (Arthropod Borne) cause three general types of disease…

Answer 12

Fever + maculopapular rash
Encephalitis
Hemorrhagic fever

Question 13

West Nile and Dengue (Arboviruses) characteristics

Answer 13

• Flaviviruses
• Enveloped ss (+)RNA, replicate similar to other such viruses
• West Nile causes mild ‘fever’ or serious encephalitis
• Dengue causes ‘fever’ or more serious hemorrhagic fever and dengue shock syndrome

Question 14

Emergence of Arboviruses:

Answer 14

Due to increased range of vector (dengue) or introduction of virus reservoir (bird, human, mosquito) into a new area

Question 15

Describe the origin of West Nile Virus starting in the Bronx Zoo…

Answer 15

In 1999, unusual deaths of exotic birds in Bronx Zoo
Crows/jays in NYC area
Birds and Culex Pipiens mosquitoes tested positive
Not long after, human cases noted

Question 16

Which year was the worst year in terms of West Nile Cases?

Answer 16

2003: 9862 cases; 264 fatalities

Question 17

Why did West Nile Virus increase in the US in 2012?

Answer 17

Unknown
Possibly weather (mild winter and hot summer)
Less water so more bird/bug interaction

Question 18

Transmission and Maintenance of Arboviral encephalitis

Answer 18

Virus reservoir in birds (in US, crows and Jays most affected by WNV)
Arthropod serves as vector to transmit from bird to bird
Horse or human - usually dead end hosts, viremia low and not transmitted back to vector

Question 19

Clinical features of West Nile Fever:

Severe Disease:

Answer 19

Clinical features of West Nile Fever: fever, fatigue, swollen lymph glands, headache, rash, eye pain
Severe Disease: Meningitis, Encephalitis, GI symptoms, Seizures, Change in mental status

Question 20

Diagnosis of WNV infection

Answer 20

High index of clinical suspicion and results of lab tests

• Consider in adults > 50 years of age or older with unexplained encephalitis or meningitis in late summer/fall
• Local WNV activity in area (dead birds)
• Vaccine available for horses
• Vaccine for humans in development

Question 21

Dengue virus - Hemorrhagic Fever

Answer 21

Dengue (a Flavivirus)

• 4 serotypes
• Mosquito transmission from human or monkey
• Causes dengue fever or “breakbone fever” - muscle/bone pain, joint pain, lymphadenopathy

Question 22

Dengue hemorrhagic fever and Dengue shock syndrome

Answer 22

• Occurs when individual antibodies against one serotype is infected with another serotype
• Non-neutralizing Ab thought to increase infection of Macs, release of inflammatory cytokines
• Causes rupture of vasculature, internal bleeding, plasma loss, and shock
• DHF/DSS on rise due to import of serotypes in new areas

Question 23

Why are non-neutralizing antibodies to a first infection with Dengue virus harmful upon second infection

Answer 23

Cause inappropriate immune response to virus

Infected monocytes release vasoactive mediators and increase vascular permeability - hemorrhage

Question 24

Diagnosis of Dengue hemorrhagic fever

Answer 24

Positive tourniquet test (>20 petechiae/inch^2)
Virus antigen detection
- ELISA to detect antibodies
- Tetravalent vaccine being developed

Question 25

Dengue is spreading due to re-emergence of the ______ _______

Answer 25

vector mosquito

Question 26

Key to Dengue virus prevention

Answer 26

Vector control

Question 27

Monkeypox

Answer 27

• Relatively rare disease occurring mostly in Africa
• Monkeypox was first isolated in 1958 in lab monkeys - later shown in African squirrel
• Virus a member of Poxvirus family
• First human case in 1970 (not generally fatal)

Question 28

Path of transmission of Monkeypox (animals)

Answer 28

African squirrel → African Rats → Prairie Dogs → Transmission to pet owners

Question 29

Path of transmission of Monkeypox (states)

Answer 29

Texas → Iowa → Illinois → Wisconsin

Question 30

Monkeypox
Incubation time:
Symptoms:
Vaccine:
Reason for emergence:

Answer 30

Incubation time: about 12 days
Symptoms: fever, headache, muscle aches, backache
Vaccine: smallpox vaccine (shares antigenicity)
Reason for emergence: Change in behavior (pet choice) and movement of virus (and reservoir) into new areas as a result of commerce

Question 31

HIV emergence
Environment:
Population:
Lifestyle changes:
Poverty:
Travel:
Sex trade:
Technology:

Answer 31

Environment: transfer of HIV from chimp to human
Population: often spurred by war
Lifestyle changes: Loss of traditional cultures, more sex partners
Poverty: Commercial sex trade
Travel: The flight attendant who had 100s of sex partners
Sex trade: in Asia - exported exposures to other Countries
Technology: Infected blood products from US