Report

Using ENSO Forecasts for Anticipating Impacts on Public Health

Current climate impact assessment methodologies for public health rely on indicators like rainfall distribution, temperature, humidity, vector population and disease cycle. These provide little time before the outbreak of epidemics to undertake public health intervention measure. The ENSO forecast on climate anomalies now available enables public health agencies to undertake potential impact assessments with sufficient lead-time. In this session, participants learned about the methodology adopted by the Philippines public health agency in exploring the possibilities of utilizing long-range climate forecasts in dealing with potential epidemics.

Presentation Highlights

Eric Tayag reported on the ECE research study that assessed the impact of climate variables such as temperature and relative humidity, and focused on dengue, cholera, typhoid, measles and malaria in Metro Manila. The correlation analysis of the time-series data from 1992-98 revealed a relationship between weather variables and dengue, malaria and cholera in the study area. Though there was a correlation between ECEs and disease outbreaks, there may be other responsible factors. Efforts may have to be made to study all factors before utilizing climate forecast information to undertake disease prevention measures. A need was noted to design forecast models and to focus on local responses for hazard mitigation and management, as well as extending data collection and analysis to all regions, over a longer time period and considering other diseases.

Discussion Points

There are strong links between the water and public health sectors. One of the biggest impacts on public health has been water-borne illnesses experienced from extreme climate-related events. At one end of the hydrological continuum, droughts can result in decreased water availability, contamination of water resources and saltwater intrusion into freshwater sources. At the opposite extreme, floods may have an impact on public health by overflowing sewage systems and cesspools and by contaminating water with minerals and non-point pollution sources.

More frequent natural hazards such as floods and droughts often create favorable conditions for the transmission of various diseases. Hence, continuous monitoring of the environment, and pathogen and host relationships, needs to be carried out. This monitoring mechanism could be useful for associating ECEs in the disease cycle.

Further research needs to be conducted on identifying the links between disease vectors and climate. Some of the changes may be in community behavior. For example, to deal with droughts, people are taught to store water; however, these stagnant water sources may be breeding grounds for mosquitoes that are the source of dengue and malaria. Reports have been issued that mosquitoes will be "fiercer" in the future from climate-dependent factors. This shows the importance of understanding the links between mosquito-borne diseases and climate effects.

The following water use management and practices driven by emergency situations during droughts and floods could contribute to the outbreak of epidemics:

• The disruption of environmental health services and infrastructure (like water supply and public sanitation) by climatic variations can contribute to a significant rise in water- and food-borne disease.
• The use of booster pumps adds to the contamination of water supply.
• The communityØs eagerness to store water during emergency situations could provide a breeding ground for vectors carrying pathogens.

There is a need to look at these behavioral practices to develop an awareness campaign for water management practices in the context of ECEs.

Other factors have been observed that may be linked to climate effects, but there has not been enough study and analysis of them. One example is the disease leptospirosis, which is found in streams, and may occur as a streamflow factor. In Vietnam, there has been an observed increase in pests during the hydrological extremes. During floods, there are increased numbers of mosquitoes, and during droughts, an increased number of mice; hence, diseases associated with these pests increase.

Recommendations

The discussions revealed that there are a number of unknown factors and research that needs to be conducted to relate climate extremes to diseases and public health risks. The participants focused on two recommendations to address the identified issues:

• Develop a multi-disciplinary and multi-dimensional approach to assess the impacts of ENSO and extreme climate events on local responses to climate-related health impacts in close cooperation among epidemiologists, entomologists, microbiologists, climatologists and other specialists. The impact that any given ENSO event will have on human health will depend not only on the prevailing climatic regime, and the specific vector and pathogen ecology, but also on human factors, including but not limited to population distribution and concentration, immune status of the population, population mobility and a whole host of infrastructural, socio-economic and environmental factors.
• Develop and use tools that improve the ability of the health sector to respond to climate-related health hazards. Coupling epidemiological models with climate models will help to utilize climate forecast information for undertaking prevention measures against disease outbreaks in the context of ECEs.