NR 518 Week 5 Outbreak Investigation Write-Up Example

Outbreak Investigation Write-Up: Three Young Men With Silicosis From One Industrial Street in Eight Weeks, Investigated in Order From Verification to a Control Measure Put In Before the Analysis Was Done

Student Name

College of Nursing, Chamberlain University

NR 518: Population Health and Epidemiology in Nursing Practice

Instructor Name

Month Day, Year

Outbreak Investigation Write-Up: Three Young Men With Silicosis From One Industrial Street in Eight Weeks, Investigated in Order From Verification to a Control Measure Put In Before the Analysis Was Done

The Signal

This write-up describes a composite investigation by a county health department in Southern California. In early spring, a pulmonologist at the county hospital called the communicable and occupational disease unit. In eight weeks she had diagnosed silicosis in three men aged 34, 39 and 44, all Spanish-speaking, all of whom cut countertops, and two of whom named shops on the same industrial street. One had been treated for tuberculosis for six months before the correct diagnosis. The public health nurse who took the call opened the line list that afternoon.

Step 1: Verify the Diagnosis

Before anything else, the team confirmed that the three men had silicosis. A county physician reviewed the chest CT reports and, for one man, the lung biopsy. All three met the county's outcome definition: imaging read as consistent with silicosis and a documented history of silica work. The tuberculosis treatment in one case was reviewed; his cultures had been negative. Silicosis does raise the risk of tuberculosis (Rose et al., 2019), so the team kept tuberculosis testing on the list of actions for every worker found.

Step 2: Is This More Than Expected?

Silicosis is reportable in California, and the state's surveillance program has documented a large and rising number of cases among engineered stone workers (Flattery et al., 2025). The question was whether three cases from one street in eight weeks was more than the county's usual share. The county's own records showed an average of about five confirmed engineered stone silicosis cases a year, scattered across the county. Three in two months from one area, all in men under 45, was well above that pattern. The team treated it as a cluster requiring investigation.

Step 3: The Line List, and Why Its Columns Mattered

The first row was written before anyone knew how large the cluster was, and the columns chosen that day shaped everything after. The nurse included case number, age, sex, preferred language, the shop and street where the person had worked, job tasks, years in the industry, main cutting method, respirator use, date symptoms began, date and place of first medical visit, first diagnosis given, date of CT, tuberculosis test result, insurance status and whether the person was still working. Two columns proved essential later. First diagnosis given showed how often silicosis was mistaken for something else, a pattern also seen statewide, where 58% of cases in one series had a delayed diagnosis (Fazio et al., 2023). Still working showed that several men were continuing to cut stone after diagnosis, which turned the investigation into an urgent prevention problem.

Step 4: Case Finding

The team searched for more cases in four places: the county hospital's records for the diagnosis code for pneumoconiosis due to silica-containing dust over the prior three years, the regional lung transplant center's referral list, two community clinics serving the neighborhood, and the state surveillance program's reports for the county. A workers' center that serves the street helped the team offer free screening. Over six weeks, eight more cases meeting the definition were found, for a total of eleven. Nine had worked in one of four shops on the street.

Step 5: Describe by Person, Place and Time

All eleven were men, aged 29 to 51, with a median of 42; ten were Latino immigrants. Their median time in the industry was 13 years. By place, nine of eleven had worked in four shops within half a mile of each other. By time, most had been diagnosed within the past 18 months, though several had symptoms for years before. Eight reported mainly dry cutting, and six said respirators were not reliably provided. Five were uninsured, and four had first gone to an emergency department. Six were still cutting stone.

Step 6: Hypotheses and Analysis

The leading hypothesis was that dry cutting of engineered stone without local exhaust ventilation or respiratory protection, in the four shops, produced heavy silica exposure. An analytic comparison was begun: coworkers screened at the same shops who did not have silicosis were interviewed with the same questionnaire, to compare cutting methods and respirator use between workers with and without disease. At the time of this write-up, the comparison was incomplete.

Step 7: The Control Measure That Could Not Wait

The team did not wait for the analysis. Six men with an irreversible, progressive disease were still being exposed, and their coworkers were exposed every day. Three actions were taken in the third week. The health department referred the four shops to the state occupational safety agency for inspection, sharing no worker names. It issued a health alert to clinicians in the county asking them to consider silicosis in young countertop workers with lung disease and to report cases. And it worked with the workers' center to offer screening, tuberculosis testing and referral to a public pulmonary clinic, in Spanish, at the center rather than the shops.

Acting before the analysis finished carried a risk: the hypothesis might have been wrong. The team judged the risk acceptable because the exposure was already known to cause the disease and the actions would help whatever the analysis showed. Statewide, surveillance findings have already led to regulatory and legislative changes, yet workers continue to face hazardous exposure (Heinzerling et al., 2026), which is why a county cannot rely on state action alone.

Step 8: Communicate and Follow Up

The team reported the cluster to the state surveillance program, presented the line list summary to the county health officer, and shared plain-language findings with workers through the workers' center. Follow-up screening at the four shops is planned for twelve months, and the analytic comparison will be completed and shared when it is done.

What the Team Would Do Differently

Two lessons came out of the first six weeks. The line list should have included a column for the shop owner's name from the start; it was added in week three, after the team realized that two shops on different addresses shared an owner and equipment, which changed how the cases grouped by place. And the clinician alert should have gone out in the first week, not the third, since each week of delay meant another chance for a worker to be treated for pneumonia or tuberculosis instead.

References

Fazio, J. C., Gandhi, S. A., Flattery, J., Heinzerling, A., Kamangar, N., Afif, N., Cummings, K. J., & Harrison, R. J. (2023). Silicosis among immigrant engineered stone (quartz) countertop fabrication workers in California. JAMA Internal Medicine, 183(9), 991-998. https://doi.org/10.1001/jamainternmed.2023.3295

Flattery, J., Woolsey, C., Fazio, J. C., Gandhi, S. A., Heinzerling, A., Harrison, R. J., & Cummings, K. J. (2025). Silicosis surveillance in California, 2019-2024: Tracking an epidemic. American Journal of Public Health, 115(11), 1913-1921. https://doi.org/10.2105/AJPH.2025.308225

Heinzerling, A., Flattery, J., Cummings, K. J., Harrison, R. J., Fazio, J. C., Gandhi, S. A., Khan, A., & Michaels, D. (2026). Silicosis among workers fabricating engineered stone ("quartz") countertops in California, 2019-2026. NEJM Evidence, 5(9), Article EVIDpha2600187. https://doi.org/10.1056/EVIDpha2600187

Rose, C., Heinzerling, A., Patel, K., Sack, C., Wolff, J., Zell-Baran, L., Weissman, D., Hall, E., Sooriash, R., McCarthy, R. B., Bojes, H., Korotzer, B., Flattery, J., Weinberg, J. L., Potocko, J., Jones, K. D., Reeb-Whitaker, C. K., Reul, N. K., LaSee, C. R., . . . Harrison, R. (2019). Severe silicosis in engineered stone fabrication workers: California, Colorado, Texas, and Washington, 2017-2019. MMWR. Morbidity and Mortality Weekly Report, 68(38), 813-818. https://doi.org/10.15585/mmwr.mm6838a1