Correll Cholera HW

8/4/2019 Correll Cholera HW

1/11

Dimple Pate

HW #10

ABE 4662

1. Problem #1.9-7

2. Answer the following questions based on the U.S. Response to Cholera Outbreak in Haiti

from the U.S. DEPARTMENT OF STATE Office of the Spokesman on November 18, 2010.

: http://www.america.gov/st/texttrans-

english/2010/November/20101119102452su0.3537976.htmla. The cholera outbreak in Haiti is caused by poor health infrastructure but also

another factor contributed significantly, what was this?

i. Since there were no outbreaks in the last 50 years, the population has no

immunity to it (compounded with the fact that this was a particularly virulent

strain), making people more susceptible to Cholera.

b. The USAID has been an initial responder to the incident what is their strategy

focused on to deal with the outbreaks there are four main parts, what are they?

i. Chlorinating/cleaning drinking water

ii. Oral rehydration therapy for those that have cholera already

iii. Educating this new generation of Haitians on care and prevention

iv. Expanding cholera treatment facilities for severe cases

c. Explain oral rehydration therapy and where was it first implemented.

i. It is a simple mix of sugar, salt, and clean water which was first implemented

in South Asia.

d. Dr. Menon from the CDC has mention their approach to help Haiti, what are they?

i. They focus on patients who make it to the hospital (reducing the fatality

rates), work with patients in the community, prevention, work on lab and

epidemiological surveillance, work on the science to adjust interventions

e. What was the cause of the initial outbreak in cholera, what was the source?

i. A breach in the water hygiene infrastructure cause by the earthquake, but

the specific source where the pathogen came from is unknown

f. Dr. Menon mentions models of South American countries, what was a key factor in

the model he describes?

i. Infant mortality played a role: higher infant mortality rates meant higher

cholera spread. Also the percentage of carriers who dont know they are

spreading the disease.
http://www.america.gov/st/texttrans-english/2010/November/20101119102452su0.3537976.htmlhttp://www.america.gov/st/texttrans-english/2010/November/20101119102452su0.3537976.htmlhttp://www.america.gov/st/texttrans-english/2010/November/20101119102452su0.3537976.htmlhttp://www.america.gov/st/texttrans-english/2010/November/20101119102452su0.3537976.html


2/11

3. Lab 14 - Epidemiological Model

a. After 150 Days:

Heavily infected population

200

150

100

50

0

0 20 40 60 80 100 120 140Time (Day)

#people

heavily infected population : ASHSandPrevInfraTEST


3/11

Cumulative cholera deaths

600

450

300

150

0

0 20 40 60 80 100 120 140

Time (Day)

#people

cumulative cholera deaths : ASHSandPrevInfraTEST

Smoothed fraction of contaminated water

0.0004

0.0003

0.0002

0.0001

0

0 20 40 60 80 100 120 140

Time (Day)smoothed fraction of contaminated water : ASHSandP revInfraTEST


4/11

b. After 10 years:

Evolution of all Subpopulations

15 M

11.25 M

7.5 M

3.75 M

0

0 365 730 1095 1460 1825 2190 2555 2920 3285 3650

Time (Day)

#people

susceptible population : ASHSandPrevInfraTEST

recovered temporarily immune population : ASHSandPrevInfraTEST

mildly infected population : ASHSandPrevInfraTEST

recently infected population : ASHS andPrevInfraTES T

heavily infected population : ASHSandPrevInfraTEST


5/11

cumulative cholera deaths

600

450

300

150

0

0 365 730 1095 1460 1825 2190 2555 2920 3285 3650

Time (Day)

person


cholera deaths

10

7.5

5

2.5

0

0 365 730 1095 1460 1825 2190 2555 2920 3285 3650

Time (Day)

person/D

ay

cholera deaths : ASHSandPrevInfraTEST

This tells us that in the next 10 years if nothing is done, the cumulative cholera

deaths will only grow in the 1st year. After that there will be no more deaths (zero

slope portion in 2nd graph) because of the immunity built up in the population. The

Rate of cholera infection will also exponentially decay over the 10 years (3rd graph).

The susceptible population will increase to a certain point and level off as people

either recover or die from the disease, and the temporarily recovered population


6/11

will decrease and level off at a very low number as less people get the disease (1st

graph).

c. Sensitivity study at 150 day simulation

i. Connectedness of the Aquifers

At half the original = 14%:

cholera infections

200

150

100

50

0

0 20 40 60 80 100 120 140

Time (Day)

person/Day

cholera infections : ASHSandPrevInfraTEST

At double the original = 56%:


7/11

cholera infections

2,000

1,500

1,000

500

0

0 20 40 60 80 100 120 140

Time (Day)

person/Day


This graph shows that increasing connectivity of aquifers increases the spike

in infection rate and slope afterwards. Also as expected, decreasing

connectivity of produces a smaller peak followed by exponential decline in

infection rates. This is because more people are susceptible to drinking

contaminated water.


8/11


9/11

i. Before change


600

450

300

150

0

0 20 40 60 80 100 120 140

Time (Day)

person


cholera infections

400

300

200

100

0

0 20 40 60 80 100 120 140

Time (Day)

person/Day



10/11

ii. After change


20

15

10

5

0

0 20 40 60 80 100 120 140

Time (Day)

person


cholera infections

200

150

100

50

0

0 20 40 60 80 100 120 140

Time (Day)

person/Day


With a higher level of prevention and better health services, the

cumulative death toll is much less and begins to level off, and the spike


11/11

in infection rate is much smaller as less people are contracting the

disease and those infected are given better care.

e. This model does not take into account direct modes of infection (contact with

contaminated fecal matter), but only assumes indirect modes (contaminated water)

It also does not take into account population growth over time since it only bases its

model on current population. And lastly, it does not take into account environmenta

factors (such as rain) that could affect transmission rates. Thi model could be

adapted to Haiti if it adjusted to reflect Haitis population, level of prevention, and

state of health services. Variables such as effect of earthquake on water hygiene

infrastructure and state of water hygiene infrastructure need to be added and taken

into account.

Correll Cholera HW

Documents

Transcript of Correll Cholera HW