A team of Epidemic Intelligence Service officers from the CDC arrives in Rhode Island, homework help

Hello!  I have the follow questions that need answered.  Do you think you can help?  

A team of Epidemic Intelligence Service officers from the CDC arrives in Rhode Island to assist the state health department with investigation and control of an outbreak of measles.  The team is asked to include the entire state in the investigation; thus, the case definition for measles in this outbreak is any resident of Rhode Island meeting the clinical case definition (you can find it at the CDC web site if you want to see it) who either has a positive laboratory test for measles IgM antibody or is a contact of someone with a positive test.  Individuals meeting the clinical case definition who did not have laboratory confirmation and were not contacts were classified as “possible cases”. 

The team members arrive in Rhode Island on March 1st.  They discover 13 individuals who met the clinical/laboratory case definition with dates of rash onset in February.  Ten of these 13 are Rhode Island residents, the other three are residents of neighboring states who were seen and treated at Brown University Medical Center in Providence, RI.  Nine of these 10 were still ill as of March 1.  The tenth, the probable index case for the outbreak, was a teenager who had traveled to Europe and returned three days prior to her rash onset.  She had recovered from her illness by the time the investigative team arrived.

During March, 31 additional Rhode Island residents were discovered who met the clinical case definition for measles, with rash onsets after March 1st.  Twenty-three of these had laboratory confirmation and 6 others were contacts of those who had.  An extensive statewide record-checking and vaccination program was undertaken throughout March, focusing on those schools, communities, and other settings where cases had occurred.  Only two of the cases had rash onset in the last week of March.

For the purposes of this exercise, use one million for the Rhode Island state resident population.

 Note:  remember to express all rates (incidence is a rate) per unit of population and per unit of time.  Prevalence (a ratio) needs only to be expressed per unit of population.

1)  What was the prevalence of measles in Rhode Island as of March 1st?

2)  What was the incidence of measles in Rhode Island for March? 

3)  What would the incidence be if possible cases were included?

4)  If all but two of the February cases, and seven of the March (confirmed) cases had recovered by March 24, what would the prevalence have been as of that date?

5)  Fill in the blanks on the following table using the formula for determining prevalence, incidence and duration (1 point each).  Complete all answers in blue.

Prevalence and Incidence of Selected Diseases

Disease

Prevalence per 100,000

Incidence per 100,000 per year

Years Duration

Epilepsy

30.8

12.2

Multiple Sclerosis

  56

  5.0

Parkinson’s Disease

157

7.85

Motor Neuron Disease

  7

  1.7

Central Nervous System

17.3

3.99

Neoplasms

10

2

6)  Observing the data in the table above, what interpretation can you give?  What applications do you find there for the clinical practitioner?  For the epidemiologist?  (5 points)?

In a city of 100,000 people, there were last year 1000 deaths and 1500 live births (none were multiple births), of which 1200 infants survived to see their first birthday.  Three mothers died in childbirth.

Calculate: 

7)  infant mortality ratio (you will often hear this called an “infant mortality rate”, but it is really not) (2 points): 

8)  crude death rate (2 points): 

14) crude birth rate (2 points): 

15)  What possible conclusions could you draw from these rates, about the overall health status of people in this city (5 points)?

Thank you,

Mindy

 

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