How many health visitors?
D000328:Adult; D000368:Aged; D002675:Child, Preschool; D003152:Community Health Nursing / Q000458:organization & administration*; D003153:Community Health Services / Q000458:organization & administration*; D004739:England; D006801:Humans; D007223:Infant; D010561:Personnel Staffing and Scheduling; D013647:Task Performance and Analysis