Outbreaks of rotavirus A diarrhoea are common among hospitalised infants, young children attending day care centres, and elderly people in nursing homes.[62] An outbreak caused by contaminated municipal water occurred in Colorado in 1981.[63] During 2005, the largest recorded epidemic of diarrhoea occurred in Nicaragua. This unusually large and severe outbreak was associated with mutations in the rotavirus A genome, possibly helping the virus escape the prevalent immunity in the population.[64] A similar large outbreak occurred in Brazil in 1977.[65]