Second National Communications Statistical models require, first, the derivation of a statistical (empirical) relationship between the current geographic distribution of the disease and the current location-specific climatic conditions. This describes the climatic influence on the actual distribution of the disease, given prevailing levels of human intervention (disease control, environmental management, etc.). By then applying this statistical equation to future climate scenarios, the actual distribution of the disease in future is estimated, assuming unchanged levels of human intervention within any particular climatic zone.38 Further evidence shows that these investigations are a good evidence based methodology. Time-series studies and geographic comparisons provide good evidence that a range of health impacts are sensitive to variations in meteorologic conditions of a scale comparable to the climate changes that are expected over the coming century or so (i.e., a 1.4���5.8°C increase in global mean temperatures, changes in regional patterns of rainfall, and potential increases in the frequency of severe storms [Intergovernmental Panel on Climate Change (IPCC) 2001a; Knutson and Tuleya 2004]39 There are four major disease surveillance systems in our country. The expanded program on immunization (EPI surveillance) focuses on the monitoring of priority vaccine preventable diseases. The HIV-AIDs registry keeps track of the number of HIV-AIDs cases. The other two data sources are the ones that have more significance to climate change which can be utilized for the study from the health aspect. These two data sources are on sentinel diseases at the Department of Health/National Epidemiology Center. These are: a) Notifiable Disease Reporting System (NDR) – this is a passive system but has a wide coverage. The information is limited by reports coming in from rural health units (RHUs) and selected hospitals. Further, there are no case definition used by the reporting units. They are used to estimate morbidity rates. It generates information on 17 diseases and 7 syndromes. Currently, this is being enhanced as part of the Philippine Integrated Disease and Response System (PIDSR). b) National Epidemic Sentinel Surveillance System (NESSS)- actively monitors 13 diseases of epidemic potential, (including the 5 sentinel diseases that are going to be covered Malaria, Dengue, Schistosomiasis, Leptospirosis and Cholera). It yields information on admitted cases of diseases with outbreak potential. It is a hospital-based surveillance system and serves as an early warning system for epidemics in the community. The system uses case definitions so the consistency is high. However, reporting units (sentinel sites) are not as widespread as the NDRS. This is actually the national module of the PIDSR. For purposes of this study, the NESSS is the database of choice. The three pilot sites have sentinel hospitals. For Albay, it is the Bicol Regional Training and Teaching Hospital (BRTTH), for Surigao it is the CARAGA Regional Hospital which is located in Surigao City and for Bohol it is the Celestino Gallares 38 Climate change and infectious diseases. Avaialable from http://www.who.int/globalchange/climate/summary/en/index5.html 39 Diarmid Campbell-Lendrum and Rosalie Woodruff. Comparative risk assessment of the burden of disease from Climate Change. Environ Health Perspect 114:1935–1941 (2006). doi:10.1289/ehp.8432 available via http://dx.doi.org/ [Online 11 July 2006] 29