Decontaminating Waters Of Pathogenic Micro-Organisms

Water is life, a timeless adage that cannot be over-emphasized. Water has been a vital component for the survival of all living organisms from human to plants and even to the tiniest of organisms on earth. Despite water covering nearly two thirds of the earth’s surface, with 97% being salty, only 0.75% of the freshwater is available for living organisms outside the salty water bodies. This forms the background of global water scarcity. Rapid population growth has led to increased water demand for industrial plants, agricultural activities and domestic use. While global warming has been the reason for shrinking glaciers and ice caps, the earths largest reservoir of freshwater; sub Saharan African (SSA) countries are faced with harsh climatic conditions and erratic rainfall patterns further exacerbating issues of water scarcity.

Water and environmental pollution is an emerging problem in the world today. Physical, chemical and biological contaminants are the major causes of water pollution. Eroded soil particles, industrial effluents, septic tank effluents, microbial landfills contents and wastes indiscriminately dumped have all found their way into the water ways and water reservoirs through surface run offs. It is estimated that two thirds of the 160m people using surface waters live in SSA with majority of them directly using untreated waters for domestic use.

Polluted surface waters are rich in pathogenic micro-organisms of different variety i.e. bacteria, viruses, protozoans. Exposure to drinking water contaminated with disease causing micro-organisms is the leading cause of infectious and waterborne diseases in SSA. Discovery of antibiotics and related medicinal drugs substantially reduced the threat posed by infectious diseases. Amyes (2001) heralded antimicrobials as the “magic bullets” that transformed the medical sector through extensive use in treatment of bacterial infections in human as well as in animals. Use of antibiotics laid down the foundations for modern medicine enabling therapies and performance of medical procedures such as organ transplants, joint operations, chemotherapy and even provision of care to premature babies. These gains significantly reduced global rates of morbidity and mortality due to infectious diseases.

Nevertheless, rising cases of antimicrobial resistant pathogens in human medicine and veterinary medicine coupled with a general decrease in the number of new antibiotics being developed pose a serious challenge to the gains realized. With approximately over 70% of known bacteria having developed resistance to one or more antibiotic classes, antimicrobial resistance (AMR) is now being recognised globally as a major public health security problem. This potential tragedy presents social, economic and political implications to the world and even a bigger blow to developing countries who bear the greatest burden of bacterial infections. Efforts to ensure environmental and public health safety through clean and safe drinking water have led to development of various water treatment modalities to decontaminate it before use. Wastewater treatment aims to achieve environmentally safe fluid waste stream and solid waste suitable for re-use or disposal. Photodynamic Antimicrobial Chemotherapy (PACT) has thus emerged as a viable alternative in decontaminating waters of pathogenic micro-organisms. Latief et al. (2015) described PACT as a concept where a non-toxic dye called Photosensitizer (PS) is restricted to the target bacteria excluding the neighbouring host tissues or cells. Activation by a low energy visible light at suitable wavelength then follows generating free radicals and singlet oxygen which are cytotoxic to the micro-organisms. According to Maisch (2007), the oxidative destruction of microbial pathogens targets the cytoplasmic membrane and DNA thus no known microbial resistance mechanism or viable recovery against PACT so far.