A Measles Outbreak in an Under immunized Amish Community in Ohio.”

Part I: Please answer the following questions: [8 points]

1. The first step in any outbreak is to make a case definition. What was the case definition for this outbreak investigation? Do you think this was an appropriate case definition (i.e. was it too narrow or too broad)? Why or why not? [0.5 points]
2. Where do you think case patients 3 and 4 acquired measles? Please defend your answer.[0.5 points]
3. In the RESULTS it states: “The corresponding reported source of exposure also changed over time; initially, the transmission setting for 38% of the cases was church, and for 48% was home; later in the outbreak, these rates changed to 5% and 90%, respectively (P = 0.10 by the chi-square test).” Please provide a possible explanation for this data. [0.5 points]
4. In the RESULTS it states: “Rates of IgM and RT-PCR positivity were 33% and 75%, respectively, in specimens obtained 1 to 8 days before the onset of rash, 92% and 83%, respectively, in specimens obtained within 3 days after the onset of rash, and 94% and 73%, respectively, in specimens obtained on days 4 to 29 after the onset of rash.” What do these two tests (IgM and RT-PCR) measure? [0.5 points] Please provide an explanation for this data (i.e. why did the percent positivity change over time and why was it different for each assay?) [0.5 points]. Assuming that all of the included cases were true positives (really had measles), if able from the data provided, please explain which test is more sensitive and which test is more specific.
   

Please define R and R0. What is the R0 for measles? (these definitions are not found in the article). How does the R0 for measles compare to other infectious disease? Is this supported by this investigation? [1 point]

Please provide an explanation for the attack rate in people > 55 year old and in children < 1 year old in Table 3. [1 point]

Please list at least 4 public health measures put into place during this outbreak.[1 point]

Could this outbreak have been prevented? In particular, please provide one thing/intervention that the State of Ohio, the relief agency, and the initial hospital where the first 4 case patients were admitted could have done differently (i.e. what measures could they have had in place prior to this outbreak or how could they have handled these patients differently – please provide one intervention for each organization)? [1.5 points]

Sample Solution