Background：In May 2012, there were increasing diarrhoea cases and deaths reported from Nabua, Camarines Sur to the Philippines event-based surveillance system. An investigation was conducted to identify risk factors and determine transmission dynamics.Methods：A suspected case was defined as a resident of Nabua with at least three episodes of watery diarrhoea per day from 16 March to 22 June 2012. A confirmed case was defined as a suspected case positive for Vibrio cholerae. An environmental investigation was conducted and rectal swabs and water samples sent to the national reference laboratory for bacterial isolation. A 1:2 case-control study matching for age and sex was conducted. Data were analysed using Epi Info.Results：There were 309 suspected cases with two deaths, and the most affected age group was children under five years (45%). Eight cases were positive for Vibrio cholerae Ogawa El Tor and one for Non-01. Water samples were positive for faecal coliforms and Aeromonas caviae. The case-control study showed that cases had a higher odds than controls of using unchlorinated water sources (odds ratio [OR] = 3.6; 95% confidence interval [CI]:1.6–8.5) and having toilets located within 20 m of a septic tank (OR = 2.7; 95% CI: 1.4–5.3). In multivariate analysis, the only significant factor was drinking from piped water (OR = 0.21; 95% CI: 0.09–0.49).Discussion：In this cholera outbreak, drinking-water from unchlorinated wells was a significant risk factor. Future cholera control efforts should include not just improving water and sanitation systems but also intensified behaviour change campaigns.

The Philippines’ Republic Act 11332 (2020) mandates prisons, jails and detention centres to participate in disease surveillance, but currently no surveillance system exists in these facilities. This report aims to describe the piloting of an early warning disease surveillance system in 21 selected jails in Calabarzon from July to September 2021. Sites were selected based on congestion, proximity to health facilities and logistical capacity. Data sources, collection mechanisms and reporting tools were determined and health personnel were trained in the operation of the system. During the implementation period, the system detected 10 health events, with influenza-like illness and foodborne illness being the most common. Nine of these events were reported within 24 hours. The local health unit provided medications for clinical management and instructed jail nurses on infection prevention and control measures, including active case finding, the isolation of cases and the inspection of food handling. Twelve sites reported over 8 of the 10 weeks, with all sites reporting zero cases promptly. The challenges identified included insufficient workforce, slow internet speed and multitasking. It was concluded that the jail-based early warning surveillance system is feasible and functional, but the perceived benefits of jail management are crucial to the acceptability and ownership of the system. It is recommended to replicate the surveillance system in other penitentiaries nationwide.