The Effectiveness Of Water, Hygiene, and Sanitation Interventions In Lowering Diarrheal Morbidity Across The Globe: A Systematic Review and Qualitative Analysis of Relevant Primary Literature

Around the globe, diarrheal disease causes millions of preventable deaths each year, with most in children zero to five years old. The transmission of disease follows a pathway in which fecal parts are spread to human hosts through fluids, tactile contact, flies, the environment, living quarters, and food. There are several barriers that can inhibit this transmission, with sanitation functioning primarily, while hygiene and potable water supply function as secondary barriers. A large amount of research has been done concerning the effectiveness of various water, hygiene, and sanitation interventions in preventing this transmission and thus lowering diarrheal morbidity across the world. In 2005, Lorna Fewtrell and her colleagues published a comprehensive metaanalysis of all the research studies published on this topic from 1970-2003. The goal of this paper is to update their findings by qualitatively analyzing the results of relevant publications from June 2003 to 2011. It compares and contrasts the results of such interventions to the reported findings by Fewtrell et al. in order to find trends in the effectiveness of certain types of interventions and the distribution of research across the world. The findings of this paper conclude that all types of interventions can be successful in lowering diarrheal rates, and that more implementation of interventions is necessary in order to eventually provide universal access to increased sanitation and potable water. The dismal amount of sanitation interventions, along with the absence of water quantity interventions and research studies performed in Oceania since 2003, highlight the crucial necessity for more research in these areas. INTRODUCTION According to the World Bank, diarrheal disease is a major cause of death across the globe due to inadequate sanitation, lack of access to potable water for consumption and usage in preparing food, and absence of hygienic behavior to reduce the transmission of disease. In Africa, a region highly affected by these issues, 115 people die every hour from resulting diseases. Children under the age of five years old are strongly affected, as 15% of all deaths in this age group are caused every year by diarrheal disease, a direct result of these global issues. In fact, of the 1.8 million people who are casualties of diarrheal disease every year, 90% are children under the age of five years old. Within this age group, the only disease that surpasses diarrhea in number of deaths is pneumonia with 18% of all deaths. These deaths, in all senses, are largely preventable. Thus, various research studies have been completed to identify which interventions effectively inhibit the transmission of fecal matter containing infectious entities, and therefore decrease rates of disease. One gram of feces may contain ten million viruses, one million bacteria, 100 parasite eggs, and 100 worm eggs all of which can result in diarrheal disease upon ingestion of fecal matter. Therefore, it is crucial that interventions are not only placed in regions such as Sub-Saharan Africa, Oceania, and Southern Asia, where these issues are most prominent, but also continued and proven to be sustainable across long periods of time. The issue of clean water is widely publicized in the media, but factors involving sanitation and hygiene are also important in preventing the transmission of diarrheal disease and must be highlighted as well. A 2012 update of the “Progress on Drinking Water and Sanitation,” published by the World Health Organization (WHO) and United Nations Children’s Fund (UNICEF) Joint Monitoring Programme on clean water and sanitation, states that the United Nations’ Millennium Development Goal (MDG) that aimed to halve the amount of people without access to potable water was successfully met five years ahead of schedule in 2010. Although this is a laudable achievement, there are still almost 800 million people worldwide (11% of the world population) with no access to safe water sources. There are also notable disparities in access between world regions and no comprehensive, sustainable method of measuring the exact proportion of people with access to potable water by country. The MDG aim to increase access to sanitation facilities is unlikely to be achieved by 2015. Over 2.5 billion people globally still do not have access to improved sanitation facilities, and if trends continue this number will only be cut by 100 million by 2015. These statistics illustrate how crucial further implementation of successful interventions is. As shown in Fig. 1, sanitation, while currently the least addressed factor in preventing transmission rates, is a vital inhibitor and primary barrier of the transmission of infectious fecal matter to the millions of vulnerable people worldwide. When implemented efficiently in a community, adequate sanitation can act as a barrier to transmission of fecal parts to fluids which can be ingested by humans either directly or in the preparation of food, transmission to flies which can disperse infectious organisms to humans through contact such as bites, and transmission by the medium of fields or floors on which feces can be present and result in transmission through the previously discussed factors. Clean water supply, currently the most addressed issue in preventing diarrheal disease, can act as a secondary barrier, when sanitation fails, to inhibit transmission to the human by preventing the direct ingestion of contaminated fluids or their use in food preparation. Hygiene acts as a secondary barrier. Proper hygiene can prevent the transmission of disease by eliminating the presence of fecal matter on finger tips and other body parts that can result in the contamination of food and water. Effective hand washing both before preparing food and before consuming it can prevent disease transmission. Proper hygiene also results in a lower volume of flies present within a given area and thus less disease will be transmitted through that pathway. Hygiene utilized in storing and handling drinking water, to reduce contamination, also bars the transmission through fluids. The cleaning of fields or floors where feces is present due to lack of adequate sanitation, yet another component of proper hygiene, can also prevent this pathway.