Summary

• During week 49 (December 4–10, 2017), activity from all causes rose slightly among children (+5%, or 4,584 visits) and adults (particularly among those aged 75 and older: +5.5%, or 2,597 visits). Hospitalizations remained stable among children and increased by 4.6% among adults (+2,720 hospitalizations).

• The majority of seasonal illnesses increased over the past week. Of particular note are: - an increase in visits for influenza/flu-like illness, both among children (+103%, or +370 visits) and adults (+60.4%, or +281 visits), - among children, an increase in visits for isolated fever (+28% among 2- to 14-year-olds), gastroenteritis (+16.5%, +532 visits), conjunctivitis (+19%, or +75 visits), and acute bronchitis (+14%, +93 visits). In contrast, visits for bronchiolitis among children under 2 years of age have stabilized. - Among adults, there was an increase in acute bronchitis (+23.3%, or +308 visits), pneumonia (+14.5%, or +435 visits), and isolated fever (+13.5%, or +127 visits).

• Among the most common conditions, excluding seasonal illnesses, there was an increase in visits for abdominal pain among 2- to 14-year-olds (12%) and for dyspnea/respiratory failure (+8.3%) and chest pain (+12.2%) among those aged 75 and older.