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120 Cards in this Set

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What is first severe and readily transmissable disease of the 21st century?
SARS
Does SARS have an animal reservior?
Yes civets or bats
How is the virus transmitted?
The virus is relatively hardy, easily spread by droplet secretions, person to person contact or fecal contamination
How long is the SARS incubation period?
two to seven days
What is the mortility rate of SARS?
10%, but in the elderly it can reach 50%
How did SARS initiially spread
First appeared in Guandong province in Nov. 2002, by Feb 2003 it was in 32 countries, by July 774 were dead
What caused the spread of SARS?
Global travel caused the spread of the virus
What is the problem if there is an animal reservior?
You can never get rid of virus because its always lurking in the population
What can you do for animal reservior?
change behavior or consider vaccinating the animal population
What is zoonosis
animal rerservior
Who is really important on the frontline with disease?
Vets!
How did the doctor start this whole thing?
Doctor from Guandong attends a wedding and infects 16 people, one guest returns to canada, doctor in hanoi sees this is a new disease and names it SARS, in March its a worldwide threat and quarantine/isolation are instituted
What types of virus is SARS
coronovirus
How did they prove it was SARS?
through koch's postulate using a monkey
Describe the SARS virus.
single-stranded, positive RNA stranded virus (it can be used directly for translation) that causes unusually severe respiratory illnesses
Herd Immunity
certain percentage of population must vaccinated to prevent the spread to others
What percent of the pop must be immunized for polio?
70%
What is another way the diseases can be spread (ie happens in birds) and food
migration and trade
What do we normally link to common source epidemics
food and water
What is the hot zone?
a highly infectious deadly virus from central African rainforest suddenly appears in the suburbs of Washington DC (true story)
What factors that increase assurance and economy in the food industry also spread disease when sanitation measures fail? What is an example?
transportation, bulk processing, central distribution
ecoli
What is the disease causing version of ecoli
ecoli O157
What is the difference between common source epidemics and others?
Causes very fast outbreaks, hosts will take more time
is ecoli always bad?
nope, its in us right now
describe ecoli as a pathogen
its ecoli O157:H7 as an emerging pathogen, also called enterohemorrhagic
What is the O antigen of ecoli?
on LPS serogroup (negative), H+ antigen+flagella=serotype
What is the leading cause of foodborne illness?
ecoli
When was ecoli first recognized as a sourcce of disease?
in 1982 when during an outbreak of severe bloody diarrhea whih was traced to hamburgers
Can the government recall meet?
Nope!
What do we do about madcow?
we can ban imports
How long does it take us to become sick after ingesting bad ecoli?
3 to 4 days
Where do cattle carry ecoli
in their intestine
How can ecoli from cows spread?
direct or indirect contact with the cow manure, it's used as fertilizer, polluted irrigation water, defacation near vicinity of produce of foods of animal origin, ie spinach
Why has ecoli recently become such a problem
We've changed how we raise cattle, feeding grain has more acidic ph which may have created an acid resistant strain
What barrier in the cow would kill ecoli usually?
acid barrier in the tummy
How does ecoli make you sick? Why don't cows get sick?
It has a toxin, but cows have a do not receptor for it
Describe the ecoli toxin.
shigalike toxin also called verotoxin, AB toxin, carried on lambdoid bacteriophage, functions as an N-glycosidase cleaving several nucleobases frm the RNA the compriises the ribosome thereby halting protein synthesis
Where are the toxin receptors?
intestinal cells and kidney cells
How do AB toxins work?
The B-Subunit is a pentamer that binds to specific glyolipids on the host cell, specifically gb3, following this the A subunit is internalized and cleaved into two parts, the A1 component then binds to the ribosomes, disrupting protein synthesis
What does the toxin require?
highly specific receptors on the cells surface in order to attach and enter the cell, species such as cattle, swine, deer can carry them any ill effect and shed them in their feces
What are other AB toxins?
cholera, diptheria, tetanus, botulism
What are type III secretions?
inject their own receptor, bind intimin, cause changes to the actin cytoskeleton
What else uses type three secretions?
yersinia pestis
What is a pathogenicity island?
region of genomic dna that we believe has been horizonttally transferred probably through transposable element, could start out with nice ecoli and get shitty ones
define Lambdoid
temperate viruses, has own DNA
What is the difference between Lytic and Lysogenic pathway?
Lysogenic can integrate host genome into the actual DNA, transduction
What kind of DNA does ecoli have?
circular
Can the prophage ever exit the cell?
yes it can jump out of the DNA if conditions aren't favorable
What kind of virus is the influenza virus?
envelope, negative stranded, has reverse transcriptase
How long does it take for influenza?
Replication takes about 6 hrs and kills the host
What are other negative stranded RNA viruses?
rabies, hanta, ebola, measles,
What is the structure of the virus?
pleomorphic (helical/ovoid), enveloped, two viral proteins extrude from the surface, the nucleocapsid houses eight segments of negative stranded RNA, RNA dependent rna polymerase, rna endonucleases
Why do we see much diversity with influenza?
genome is segmented
How many proteins do the 8 segments code for?
11
What are the most characterized viral proteins on influenza
hemagluttin and neruminidase, two large glyoproteins on the outside
What is Neraminidase?
an enzyme involved in the release of progeny virus from infected cellsby cleaving sugars that bind the mature viral particles
What is Humagluttinin
a lectin that mediates binding of the virus to the target cell and entry of the viral genome into the target cell
What are some methods of detecting viruses
antibody based detection systems, PCR based systems, culturing the virus from infected tissue
Can we always culture a virus? What do we use to culture it?>
No we can't, but if we do its down with chicken eggs
How does PCR work?
PCR 1. Initialization step the DNa is heated to denature it it (pull it apart by breaking the hydrogen bonds, annealing step: temp lowered so primers can attach, elongation step: new DNA is synthesized
You have to use an RNA polymerase
Need DNA
Why do epidemics and pandemics occur?
antigenic variation and antigenic drift
Antigenic drift
a slow process attributed to the tendency for RNA viruses to acquire mutations, RNAP lacks proofreading causing slight alteration that may result in the ability to escape the immune system-causes epidemics
Antigenic shift
a fast process due to a segmented genome, if two genitically and antigenetically distinct viruses infect the same cell then thier genome segments can reassort to form unique progeny-this causes pandemics
How many HA serotypes?
16
How many NA serotypes
9
How much of the population needs to be vaccinated to get herd immunity for influenza?
90 to 95%
Why is the rhesus moneky used for animal studies?
their response to infectious disease
What is now an issue with polio?
people don't want to immunize their children
What killed more Spanish flu or WWI
spanish flu
How many people did the flu kill worldwide
50 million
What part of the human body does influenza dispay high growrth ability in?
lung cells
Why did they think swine flu is related to the 1918 flu?
we had antibodies against swine flu
What animal do we use to test the flu?
ferrets-we used for dog distemper first
What is Avain flu?
H5N1
When and what were the three pandemics of the last century?
1918: H1N1
1957: H2N2
1968: H3N2
How many mutations make 1918 a big bad killer.
two point mutations and it cannot be transmitted from place to place
What happened in 1976 with swine flu?
we went a little crazy
Why couldn't people make a vaccine for everybody?
Nobody wanted the liability
Why was the specimen that was frozen good?
she was obese
Whats not so hot about killing chickens to produce bird flu?
we need them for eggs
What disease was linked to the flu vaccine?
Guillai-Barre, a nervous system disorder
how many biosafety level 4s are there?
10 in USA
What are the two sources for sequence info
tests in chicks and mice
How does HA bind to host cell?
Through alpha 2,6 in humans and in alpha 2,3 in birds
how does microarray analysis work?
if gene is highly expressed you'll have lots of it, there is a corresponding oligonucleotide corresponding to a sequence, If hybridize green and red you see yellow if they’re equal, red genes are more in n=known control
What might have actually caused?
immune system is overreacting, doesn't let normal course happen, die of overactive immune response
Who has a better immune system?
Healthy people
Abberant immune response
overactive immune response
What are intervenetions we can make for the flu?
vaccination, antiviral, neuraminidase inhibitors such as tamiflu which is fed to chickens, non drug methods such as masks, social distancing
Why did St. Louis have lower infections?
St Louis did early social distancing
How fast is our population increasing?
faster than exponential
How must we consider population?
in terms of number and denisty
What is density?
population size/ area
what do density models define?
how much people come into contact with each other
What does the united nations define as an urban area? us? iceland?
more than 20,00 residents, Us 2500, iceland 200
What are megacities? How many will there be in 2015?
more than 10 million, 23 by 2015 with 19 in developing countries
what was the first country to exceed 1 million people?
Peking
How much of an increase does the Un predict will occur in the next 30 years
2 billion more people
how much of the worl'd resources does the US use?
30%
What is the difference between developed and developing countries?
in developed people are living in smaller cities
How many megacities will Europe add by 2015?
zero
What was the first megacity?
NYC
What is a major issue in cities?
water
What fraction of people lack safe water?
1/6
What percent of the world lacks feasible means of sanitation?
50%
What is water most of the time?
65 to 70% for irrigation
How many gallons does it take feed a person for one day?
528
Are bigass cities a new thing?
tikal is an old city
Where were the earliest settlements?
The fertile crescent of Mesopotamia
why did large urban areas develop?
trade and commerce
do cities have ecology?
yes
Why are urban areas heat islands?
because of asphalt absorbs heat and releases it
When does heat island mainly effect?
at night
Why is baltimore hotter and phoenix cooler?
because phoenix sweats when they irrigate grass and it secretes water
Where is precipitation higher?
in and downwind of cities
What is the diffference in percipitation in cities vs rural?
43% of precipitation exits cities via storm sewers vs towns where 50% of it ends up in groundwater
What are two problems from cities?
Cause atmosphere to dump water at higher rate also immediately gets swept away
How do city forests differ?
fewer species, lower density, and more species that are adapted to wet soil
What happens to all the bigger predators?
They go away
What animals do cities have
feral, cats, and dogs, lots of midsized predators, scavengers