Figure 3. Symptom scores of infected animals reflect development of human-like symptoms.

Symptoms were scored as follows: nasal discharge, 1 point; sneezing, 1 point; labored breathing, 3 points. Each animal was observed at least once daily throughout the experiment; symptoms were recorded for the days shown. The graphs show the summed symptom scores for each index (A) and contact (B) animal on each day on which symptoms were recorded.