HLTH 3115 Week 7 Surveillance Analysis Example

From Theme Park Exposure to Published Report: The 2014-2015 California Measles Outbreak Followed Through Each Surveillance Handoff, With the Delay at Every Step That a Source Recorded

Student Name

Walden University

HLTH 3115: Public and Global Health

Instructor Name

Month Day, Year

From Theme Park Exposure to Published Report: The 2014-2015 California Measles Outbreak Followed Through Each Surveillance Handoff, With the Delay at Every Step That a Source Recorded

The Event

In early 2015, news reports described a measles outbreak linked to two adjacent Disney theme parks in Orange County, California. In the coverage, the outbreak appeared all at once. This analysis follows it through the stages of surveillance, from the case definition that determines what counts, through detection and reporting to public health authorities, to publication in the national surveillance report, and records the delay at each handoff wherever a published source gives the dates. The measles virus genotype identified in the outbreak, B3, had recently caused a large outbreak in the Philippines and had been detected in at least 14 countries (Zipprich et al., 2015), so the event is also an example of how a disease circulating abroad enters a country's surveillance system.

Stage 1: The Case Definition

Surveillance begins with a definition, because only cases that meet it are counted. The national case definition for measles in the United States describes the clinical illness as a generalized rash lasting at least three days, a temperature of at least 101°F (38.3°C) and cough, runny nose or conjunctivitis (Centers for Disease Control and Prevention, 2013). A confirmed case requires laboratory evidence, such as a positive test for measles-specific IgM antibody or measles virus genetic material, or a direct link to a laboratory-confirmed case. The definition also sets the exposure period as 7 to 21 days before rash onset. Every date in the sequence below depends on this definition: exposure is dated from it, and a case is confirmed only when it is met.

Stage 2: Exposure and Onset

The patients linked to the parks reported visiting them during December 17-20, 2014 (Zipprich et al., 2015). The first reported patient, an unvaccinated 11-year-old, had rash onset on December 28. That is 8 to 11 days after the exposure window, which fits the definition's 7- to 21-day exposure period. This interval is biological, not a surveillance delay; nothing in the system could have shortened it.

Stage 3: Detection and Notification

The California Department of Public Health was notified of the suspected case on January 5, 2015, eight days after the child's rash began. The report does not say how much of that interval passed before the child was seen, before measles was suspected or before a local health department forwarded the report. That is the most important missing detail in the sequence: an eight-day delay could reflect a family waiting to seek care, a clinician not considering measles in a disease that many had never seen or a reporting chain between local and state agencies. On the same day, the state received reports of six more suspected cases in California and Utah residents, all of whom had visited the parks.

Table 1

Surveillance Handoffs and Recorded Delays

Each delay is counted from the date of the step above; the 8-day delay to notification is the gap between the first patient's rash and the state's first report of the case.

Stage 4: Confirmation and Alert

By January 7, two days after the first notification, seven California cases had been confirmed, and the state issued a press release and a notification through the national Epidemic Information Exchange to other states (Zipprich et al., 2015). This was the fastest handoff in the sequence. It was fast because the cluster was already visible: several suspected cases with a shared exposure arrived together, and the shared exposure itself suggested an outbreak.

Stage 5: Publication

The outbreak was described in the national weekly surveillance report as an early release on February 13, 2015, and in the regular weekly issue on February 20 (Zipprich et al., 2015). By February 11, the report counted 125 confirmed cases with rash onset from December 28 to February 8 in U.S. residents linked to the outbreak, 110 of them in California. The 37 days between the alert to other states and the national publication were not 37 days of silence; the alert had already reached health departments. Publication served a different purpose: a citable, analyzed account for clinicians and the public, including the finding that 45% of California patients were unvaccinated.

What the Delays Show

Jajosky and Groseclose (2004), reviewing timeliness in U.S. surveillance, found that published evaluations rarely measure timeliness in a standard way and that national reporting delays from disease onset varied widely by disease. This event fits that picture: the published report gives some dates exactly and leaves others out. The delays it does record show a pattern common to outbreaks. The longest surveillance delay, eight days from onset to state notification, occurred before the system knew there was an outbreak, when the case was a single sick child. Once a cluster was recognized, confirmation and alerting took two days. Publication took longer, but by then it was not the step on which the public health response depended.

What Cannot Be Measured From the Sources

The published report does not record when the first patient sought care, when measles was first suspected or when specimens reached the laboratory. Those intervals would show where the eight-day delay accumulated and which part of the system could shorten it. Their absence is itself a finding: the sources that compress an outbreak into a headline also compress the early surveillance steps, where the largest delay occurred.

Conclusion

Followed through its handoffs, the outbreak shows a biological interval of 8 to 11 days from exposure to rash, an 8-day surveillance delay from rash to state notification, a 2-day step from notification to confirmed cluster and national alert and 37 more days to a published analysis. The case definition shaped every one of these dates. The longest avoidable delay came before anyone knew there was an outbreak, which is the stage that headlines skip.

References

Centers for Disease Control and Prevention. (2013). Measles (rubeola) 2013 case definition. National Notifiable Diseases Surveillance System. https://ndc.services.cdc.gov/case-definitions/measles-2013/

Jajosky, R. A., & Groseclose, S. L. (2004). Evaluation of reporting timeliness of public health surveillance systems for infectious diseases. BMC Public Health, 4, Article 29. https://doi.org/10.1186/1471-2458-4-29

Zipprich, J., Winter, K., Hacker, J., Xia, D., Watt, J., & Harriman, K. (2015). Measles outbreak: California, December 2014-February 2015. Morbidity and Mortality Weekly Report, 64(6), 153-154. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6406a5.htm