Table 1.

Surveillance factors and their risk assessment quintiles

Factor	Risk assessment value
	1	2	3	4	5
1. Temperature (°C)	≤13	14–18	19–22	23–26	>26
2. Adult Culex abundance (%)	≤50	51–90	91–150	151–300	>300
3. Virus infection incidence per 1,000	0	0.1–1.0	1.1–2.0	2.1–5.0	>5.0
4. Number of sentinel chicken seroconversions	0	≥1 Kern	1–2 in 1 flock	>2 in > 1 flocks	>2 in >2 flocks
5. Number of dead birds positive	0	≥1 Kern	≥1 BKSF	2–5 BKSF	>5 BKSF

Kern, throughout Kern County; BKSF, specifically in the Bakersfield area.