Methodology

Methodology

Definition & Validation

The NoroProxy metric is defined as illness reports where symptoms include both vomiting and diarrhea concurrently. This specific symptom pattern has been validated as a reliable proxy for norovirus-like illness, representing approximately 30-50% of illness reports in comprehensive analyses.

Scientific Basis

The methodology is supported by epidemiological research demonstrating that the co-occurrence of vomiting and diarrhea has high specificity for norovirus infections compared to other common foodborne or communicable illnesses. While not diagnostic at the individual level, this pattern provides statistically significant population-level insights.

Correlation with Official Data

Excerpt from Infectious Disease Week Poster:

As shown in the chart above, the IWP and NoroSTAT datasets move in tandem: a Pearson correlation of 0.67 (p < 0.001) reveals a clear, straight-line link over time, and a Granger causality test (p = 0.003) shows that shifts in one dataset reliably predict shifts in the other. Together, these results demonstrate that real-time crowdsourced reports closely mirror official surveillance data—highlighting their promise for spotting norovirus outbreaks earlier.

Additional Materials

IAFP presentation

3MB

IAFP 2024 - Correlating Self-Reported Norovirus-Like Illness with Epidemiological Data - Linkedin.pdf

pdf

Infectious Disease Week 2024 Poster:

796KB

ID Week Poster V4 JF Edits.10_14_2024.pdf

pdf