Norovirus gastroenteritis outbreak by person to person transmision in a nursing home

BACKGROUND AND OBJECTIVE: The-aim of this study was to conduct an investigation into an out rea of gastroenteritis among health workers and residents (with different grades of dependence) at a nursing home. PATIENTS AND METHOD: We detected an outbreak of gastroenteritis in a group of 52 health workers and 124 residents at a nursing home in Oliana, Lleida (Spain). A bidirectional prospective and retrospective cohort study was conducted into the consumption of water, food, grade of dependence (high, medium and low) and specific job. We studied the water supply and 6 food items. Faecal specimens from 30 patients were cultured and examined for Norovirus by polimerase chain reaction-reverse transcription. The possible implication of different factors associated with gastroenteritis was assessed by relative risk MR) at 95% confidence intervals (CO. RESULTS: We interviewed 97.7% of the patients (172/176). The overall attack rate was 53.3% (92/172). The symptoms were: diarrhoea 68.5% (63/92), vomiting 64.1% (59/92), nausea 63.0% (58192), fever 33.7% (31/92), abdominal pain 28.3% (26/92), and headache 14.1% (13/92). The,epidemic curve, highlighted transmission for 19 days. The risk factors associated with gastroenteritis were high (RR = 1.6; 95% CI, 1.0-2.6) and medium (RR = 1.7; 95% CI, 1.0-2.7) levels of dependence, health worker with high level of contact with residents (RR = 2.8; 95% CI, 1.1-7.3) and those doing cleaning work (RR = 2.8; 95% CI, 1.0-8.0). Bacterial cultures were negative for samples of food and water. Also, cultures were negative for bacteria in faecal samples but tests were, positive for Norovirus in 12 faecal samples. CONCLUSIONS: We showed a Norovirus outbreak in a nursing homes, person to person spread associated to high and medium grades of dependence among residents, health workers with high level of contact with them and with those doing cleaning work.