Intro to Public Health Exam 2

What is the difference in exempted children from 1991 to 2004 in the US?

In 1991 only 1% of children were exempt from vaccines whereas in 2004, 2.5% of children were exempt

What is unique about vaccine exemptions in New York, New Jersey, Florida, and Connecticut?

There are no personal vaccine exemptions allowed

When does "herd immunity fail?

When too many people in a population opt to not get vaccinated

According to Dr. Offit in the 2007 Wall Street Journal article, how does the rate of pertussis cases in children compare in states with easy vaccine exemption laws vs. states with difficult or no exemption allowed?

States with easy exemption increased children's chances of getting pertussis by double

According to Dr. Offit in the 2007 Wall Street Journal article, can measles be fatal?

Yes. it causes fatal pneumonia

What does Dr. Offit say about individual rights, freedoms, and philosophical exemptions?

He states that more and more children will die from preventable diseases

According to Table 4.3 how many diseases have had >95% reduction in the US since the vaccines came into use?

10

Is measles still epidemic in the US? Do we still require the vaccine in most states? Why or why not?

-Yes. More and more people are not getting vaccinated which is causing large outbreaks

-In 2005, a 17 year old unvaccinated girl went to romania and brought measles back to her church in Indiana of 500 people, many of which were unvaccinated. This was the largest measles outbreak in 10 years.

Give 2 common helminth diseases in the U.S.

Pinworms

toxocara

What is the mode of transmission for most helminths?

-Touch, fecal oral route

-Live in the colon and rectum. At night females leave through the anus and deposit eggs

Are worm diseases important in the U.S.? How important?

Yes. They still cause much disease in the U.S and worldwide, although are not usually fatal.

What helminth disease is of concern from litter sand boxes or grass areas where lots of dogs play?

toxocara

Are helminth diseases normally deadly?

No

What are some serious outcomes of worm diseases (hint: toxocara)?

Can reach brain damaging learning and cognition

List 6 control measures that work before infection

hand washing, immunization, disinfection, quarantine, water purification, PPE

List 6 control measures that work after infection

immune system, quarantine, antibiotics, antitoxins, anti microbials, supportive care

Name 2 control measures that can be applied both before AND after infection.

Quarantine and immune system

List 3 essential characteristics of an effective vaccine.

safe, effective, stability

List the 5 desired characteristics of a vaccine.

cost, nasal or oral administration, stable at room temp or tropical temps, one dose is effective, shelf stable

Define R0 (R-naught).

-Indicates how contagious and infectious disease is

-The approximate number of people each infected individual will infect (in a population with no immunity)

-The higher the value, the more contagious

Define herd immunity.

The % of the population that must be immune in order to prevent spread of the disease

If measles has a Ro of 15, what % of the population must be vaccinated or immune in order for it not to spread through the community?

1-1/15 = .93 = 93%

For a disease with a Ro of 20, what % of the population must be vaccinated or immune for it not to spread through the community?

1 - 1/20 = .95 = 95%

Be able to look at a table of Ro values and tell which disease is most contagious

Higher number = more contagious

What 3 areas does One Health attempt to consolidate?

Human heath, animal health, and environmental health

What 3 species have the highest number of viruses shared with humans?

Bats, rodents, non-human primates

List the human behaviors that increase zoonosis in modern times

Growing population and expanding into close contact with animals, changes in climate and land use such as deforestation, international travel and trade have increased, illegal wildlife trade

According to Dr. Tarbet, _____ of new and emerging human diseases in the past 3 decades were of zoonotic origin

70%

What is the reservoir for Hantavirus?

Scat (rodents)

What is the mode of transmission for Hantavirus?

airbone from rodents

In 2004 the H3N8 flu virus jumped from horses to

dogs

Is there a vaccine for dog and horse flu

Yes

Highly pathogenic flu (H5N1 avian in 2003 and H7N9 in 2017) crossed from its normal reservoir of _____ to humans. It infects the lower respiratory tract and has high mortality (about 60%). A big PUBH fear is if this virus adapts to human-to-human transmission it may likely cause a deadly pandemic.

birds

A unique feature about influenza disease is that the infected host sheds virus 1-2 days before onset of disease signs/symptoms. Why does that increase the spread of disease?

Because no symptoms are shown, the virus is more easily spread as individuals are not staying home

List 2 "collateral damage" effects of a pandemic

-Panic and fear can cause global governance to be challenge and people's behavior and activities to be unpredictable

-The supply chains for critical products like drugs and medical supplies will be threatened

Screening Tests

the presumptive identification of unrecognized disease or defects by the application of tests, examinations, or other procedures that can be applied rapidly. Positive screenings are followed by a diagnostic test to confirm disease.

Diagnostic Test

confirm actual disease. Take longer than screening

What are the 5 characteristics of a "good" screening test?

Simple, rapid, inexpensive, safe, acceptable

Be able to list an example of a social, scientific, and ethical justification for implementing a screening tool.

-Social: is it a major health problem to the community?

-Scientific: is the prevalence of the disease high?

-Ethical: Are effective methods of prevention available?

Define reliability of a tool.

Precision. The ability of a measuring instrument to give consistent results on repeated trials. Test gives the same result.

Define validity of tool.

Accuracy. The ability of a measuring instrument to give a true measure. Is it measure what we want it to measure?

Define sensitivity.

-The ability of the test to identify correctly individuals who actually have the disease (a/a+c)

-# who screen says are sick / # who are really sick

-% chance the screening test will say that a sick person is sick

Define specificity.

-The ability of the test to identify only non-diseased individuals who actually do not have the disease (d/b+d)

-# who screen says are healthy / # who really are healthy

-% chance the screening test will say that a healthy person is healthy

Predicted value positive:

% chance you really have the disease if the test says you have it

Predicted value negative:

% chance you are healthy if the test says you are

Know how the COVID rapid antigen assay (receive results within 15 minutes) compares to the gold standard RT-PCR test.

Rapid antigen: specificity 100%, sensitivity 84-97.6% compared to PCR test

null hypothesis

-States there is no difference among the groups being compared

-There is no association between air quality and dying from lung cancer

significance level.

The chance of rejecting the null hypothesis when it is true

P-value

Expressed the probability that the observed result could have occurred by chance alone

Know what a P-value of < 0.05 and

-P = .05 = 95% confidence that the results are really different

-p

confidence interval

-A computed interval of values that, with a given probability, contains the true value of the population parameter

-Stated as a percentage

-95% confidence interval means we are 95% confident that the true average of the whole population is within the given range

Know how sample size affects confidence interval.

larger sample size normally gives smaller confidence interval; the bigger the sample, the more it will predict what the whole population looks like.

Risk perception

the perceived knowledge of the public. More dreaded and unknown

Risk assessment

estimates the probability of occurrence and the extent of harm that may be caused

Be able to apply a cost-benefit analysis to a public health issue.

-Weighs the estimated cost of implementing the policy against the estimated benefits

-Costs are easier to calculate than benefits

Effective vaccines are possible, but each year scientists must develop a new variation of the vaccine. Why?

Because there are different variations and mutations

minimize the false positives.

When you want to make sure people who are negative really are negative

minimize the false negatives

When you want to make sure people who are positive really are positive

Example question: We have two different tests to diagnose a disease. Test A has a sensitivity of 98% and a specificity of 80%, while test B has a sensitivity of 75% and a specificity of 99%.

Which test is better to find the disease in everyone who has it?

Test A

Example question: We have two different tests to diagnose a disease. Test A has a sensitivity of 98% and a specificity of 80%, while test B has a sensitivity of 75% and a specificity of 99%.

Which test is better to rule out the disease in healthy people?

Test B

Example question: We have two different tests to diagnose a disease. Test A has a sensitivity of 98% and a specificity of 80%, while test B has a sensitivity of 75% and a specificity of 99%.

Which one will give more false positive results?

Test B

Example question: We have two different tests to diagnose a disease. Test A has a sensitivity of 98% and a specificity of 80%, while test B has a sensitivity of 75% and a specificity of 99%.

Which one is more likely to be used as a screening test?

Test A

How p value is used in comparison studies

The better the p-value, the more likely the test is going to be right.

What a confidence interval is used for

Says how likely that your hypothesis is right

Practice question: With sample size of 20, the odds ratio is 2 with a confidence interval of (0.5, 7.7). Do you conclude the exposure is associated with the disease or not?

Yes; associated with disease

Know how sample size relates to statistical power.

bigger the sample = bigger power

Be able to differentiate between cause-and-effect relationship and association.

Association is correlation not causation

Know the challenges and complications of screening assays, especially those based on perception and behavioral screenings.

-Difficulty with behavioral and mental health diseases to determine exactly what they have. You can't do a quick, easy screening test

-Difficult to identify that causes are due to the disease. It is a spectrum of symptoms

3 main sources of public health data.

Vital statistics

Census

surveys

Know the major vital statistics reported that affect public health

-Birth certificates, death certificates, spontaneous fetal deaths, abortions, marriage and divorce rates

-Notifiable diseases

-Local health departments → states → national center for health statistics (part of CDC)

sources of error in vital statistics.

-Deaths: causes inaccurately reported to protect patients, families

-Complex pathologies

-Mis diagnosed cause of death

Know sources of error in the US Census.

-Sampling errors

-Missed homes (homeless, undocumented, 10 M missed in 2020)

-Double counts (individuals w/> 1 home, 36K counted twice)

-Mixed race

the 3 major surveys used in the PUBH in the U.S.

-ACS: American community survey

-NHANES: national health and nutrition examination survey

-BRFSS: behavioral risk factor surveillance system

Know how the census's total population count affects all public health statistics and reporting.

-Is not a public health measure, but helps understand public health.

-Shows geographic distribution, sex, age, ethnicity, race, household status

Coroner

-Part of the public health department

-Ensures accurate death certificates

-Monitors trends in epidemiology

-If patient is mis-diagnosed and treated, similar cases in the future will likely be decreased

NHANES (National Health and Nutrition Examination Survey)

-Doctors and nurses go around the country conduction physical and dental exams, lab tests, and anthropometrics

-Small sample size due to this being in person and there are not enough professionals to test everyone

Census

-Pros: shows the population - geogoraohy, sex, age, ethnicity, race, househould status

-Cons: sampling errors, mixed races, double counts, and missed homes

ACS

-Pros: provides info on education, income, employment. Large sample size, important information for community planning and social services

-Cons: intrusive. Only sent to 3M houses/year

NHANES (pros and cons)

-Pros: accurate, trained data collectors

-Cons: expensive, small sample size

BRFSS

-Pros: large sample size

-Cons: based on self reports

notifiable diseases

-Diseases that must be reported to the health department

-Shows outbreaks in diseases

qualative data

-Describes qualities or characteristics

-Done through interviews, focus groups, participant observation

-Shows peoples feelings, reasons, perceptions/thoughts, experiences

-Answers how and why of a disease, behavior, or condition

-Use when you want to understand something deeper.

Quantitative data

-Uses values or counts

-Assess the health of the population through questionnaires, surveys, medical tests

-Use when you want to confirm or test something

-Shows prevalence, incidence, trends, correlation between variables

What is the main goal of epidemiology?

Apply findings to control disease or health concerns

How is epidemiology important in disease prevention?

They help to identify cause of the disease, source, and methods for control

What is the cause of Leishmania and how is it transmitted? Is it zoonotic?

Parasitic disease caused by the bite of sand flies. It is a zoonotic disease

Which cancer has the highest incidence? Which cancer has the highest death rate?

-Highest incidence: breast

-Highest death rate: lung

Are these cancers affected by multiple determinants or mostly by a single determinant? Are cultural factors disease determinants?

-Multiple determinants

-Yes cultural factors are disease determinants

How are epidemiologists and epidemiology important in 2020 in tracking, identifying, and eliminating the local and national opioid epidemic?

-Tracking opioid prescriptions and deaths caused by opioids or related to opiods

-Creating policies that defer from prescribing opioids

What were the main determinants for the 2015-2016 Zika outbreak originating in Brazil?

vector, geography, lifestyle, gender.

For what population is Zika most serious?

Childbearing aged women

Besides vector transmission, in what 2 ways can Zika be transmitted?

-Sex and in a fetus

-Vertical transmission (mother to baby)

Use cardiovascular/heart (CDH) disease, HIV, and TSS as examples of disease distribution among populations

-CHD rates higher in african americans

-HIV rates high in African born immigrants living in Utah

-TSS higher in women

How is it that the rate of HIV can be higher in African American males in Utah, yet most cases are in Caucasian males.

Since they are immigrants, they may have developed HIV in Africa where rates are higher. They are already part of the prevalence, but there is more new cases of HIV in white males increasing the incidence

Explain epidemiology's mission in terms of "explain, predict, control."

-Explain the etiology of disease

-Predict the occurrence of disease

-Control the occurrence of disease

endemic

a disease regularly found in one area

epidemic

widespread occurrence of a disease

antharax epidemic

1 case of anthrax was an epidemic because we do not expect to see any cases

What type of epidemiological study could be done now using known cases of Lyme disease to show a connection between out-of-state hiking and Utah Lyme disease cases?

Case control study; odds ratio

Contrast incidence and prevalence.

-Incidence is the amount of new cases

-Prevalence is the amount of existing cases