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How are arboviruses acquired? How do they spread?
Acquired by an insect either through vertical transmission or blood meal
Spread in the blood
What are the 4 vectors that were discussed in class?
mosquito
sand fly
midge
tick
What is the difference between a reservoir and non-reservoir host?
Reservoir: a host that does not experience the symptoms of disease when infected by the pathogen
non-reservoirs: show symptoms of the disease
Why is it virtually impossible to eliminate arboviruses?
insect and vertebrate reservoirs
What kind of virus is Yellow Fever Virus? Where does it get its name? Roughly how many people get severe disease from Yellow Fever Virus?
Kind: Flavivirus (+) RNA virus
Name: jaundice associated with the disease
Causes severe disease in about 1/3 of people infected
What organ is the primary target of YFV? How many people get infected and how many die from this virus each year?
Organ: liver
200,000 cases; 30,000 deaths/year
Be able to explain the difference between the Sylvatic cycle and the Urban cycle of transmission. Which mosquitos promote transmission in each cycle for YFV?
Sylvatic cycle: Haemagogus, Aedes africanus
Urban cycle: Aedes aegypti
What are some of the impacts that YFV has had on society?
1801 most troops died from YFV
Mexican-American War: 10X more soldiers were killed by YFV vs battle
1901 Walter Reed confirmed route of infection and nature of the agent of disease
Panama Canal: too many workers dying of YFV
Why is YFV less prevalent than other Arboviruses discussed?
Vaccine that affords lifelong protection from YFV
What type of virus is Dengue virus? Where is the virus prevalent?
Type: Flavivirus
Prevalent in Asian and Latin American countries
How many people are infected, get severe disease, and die each year from Dengue? What are the ranges of disease caused by Dengue virus?
Infected: ~400 million/year
Severe disease: 500,000/year
Death: 2.5% will die/year
95% is asymptomatic or mild
5% is severe, life-threatening fever/shock syndrome
The headaches and muscle aches caused by Dengue have given it the alternative name - fever.
Break-bone
Why is Dengue more severe the 2nd time you get infected?
immune response actually makes the clinical symptoms of dengue worse, increasing the risk of severe dengue
(ADE)
What is antibody-dependent enhancement? Describe how this functions to enhance Dengue virus replication? Why does it make vaccine development a nightmare?
Antibody dependent enhancement (ADE)
virus fools adaptive immune response because antibodies made against one serotype can cross-react with other serotypes
those antibodies are unable to neutralize virus of a different serotype
virus infects these cells, kills them, and produces even more progeny that are released into the bloodstream
What type of virus is Chikungunya virus (CV)? Where was it first identified? Where was the large outbreak that resulted in a rapid increase in the incidence of disease?
Type: Togaviridae (Alphavirus) (+) RNA
Identified: Tanzania in 1952
Large outbreak: Reunion Island in the Indian Ocean
What areas are at risk of Chikungunya?
Countries in African and Southeast Asia
What is the major symptom of Chikungunya that does not go away?
Joint pain
What are petechial spots?
pinpoint, round spots that appear on the skin as a result of bleeding
What type of cells carry CV into the synovial tissue of joints?
infected monocytes and macrophages where the inflammatory response is established
How did CV enhance its transmission/geographical range following the outbreak on Reunion Island?
single amino acid change in E1 glycoprotein changed its ability to infect and now it infects aedes albopictus
What treatment(s) can be given to address chikungunya disease?
anti-inflammatory drugs to reduce pain
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