Getting Technical
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of water safety plans incorporating the safe disposal of human waste so that drinking water supplies are not contaminated . However , most studies agree that improving the sanitation , hygiene and management of water resources could prevent at least a further ten percent of total global disease .
About half of the hospital beds occupied in the world are related to the lack of safe drinking water . Unsafe water leads to the over 80 % of global cases of diarrhoea and 90 % of the deaths of diarrhoeal diseases in children under five years old . Most of these deaths occur in developing countries due to poverty and the high cost of safe water . An article published in 2003 by the CDC – the Centre for Disease Control , a United States federal agency under the Department of Health and Human Services – concluded that the death of children at under five years of age caused by rotaviruses ranges between 352 000 to 592 000 per annum on a global scale .
Over 1 billion people do not have access to improved water and more than 2 billion people do not have access to sanitation facilities . This situation leads to 2 million preventable deaths each year .
Cynthia Mathew , a researcher at the University of Canberra , recently wrote a short , lucid , introductory article on viruses from which some extracts and comments are presented below .
Viruses are mostly regarded as having aggressive and infectious natures which is true in the sense that most viruses have a pathogenic relationship with their human hosts in that they cause diseases ranging from a mild cold to serious conditions like severe acute respiratory syndrome ( SARS ).
But not all viruses are bad . Some viruses kill bacteria , while others can fight against more dangerous viruses . In fact , there are several protective viruses in human bodies , often referred to as ‘ probiotics ’.
Bacteriophages , or ‘ phages ’, are viruses that infect and destroy specific bacteria . They are found in the mucus membrane lining sections in human digestive , respiratory and reproductive tracts .
Mucus is a thick , jelly-like material that provides a physical barrier against invading bacteria and protects the underlying cells from being infected . Recent research suggests the phages present in the mucus are part of natural immune systems protecting the human body from invading bacteria .
Phages have , in fact , been used to treat dysentery , sepsis caused by Staphylococcus aureus , salmonella infections and skin infections for nearly a century . Early sources of phages for therapy included local water bodies , dirt , air , sewage and even body fluids from infected patients . The viruses were isolated from these sources , purified , and then used for treatment . Phages have attracted renewed interest as the rise of drug-resistant infections continues . Recently , there was a report on a teenager in the United Kingdom who was close to death when phages were successfully used to treat a serious infection that had been resistant to antibiotics .
Nowadays , phages are genetically engineered . Individual strains of phages are tested against target bacteria , and the most effective strains are purified into potent concentrations . These are stored as either bacteriophage stocks ( cocktails ), which contain one or more strains of phages and can be used to target broad ranges of bacteria . Alternatively , particular phages can be selected from phage stocks to target specific bacteria . Treatment can be safely administered orally , applied directly onto wounds or bacterial lesions , or even spread onto infected surfaces . Clinical trials for intravenous administration of phages are ongoing .
Viral infections at a young age are important to ensure the proper development of our immune systems . In addition , the immune system is continuously stimulated by systemic viruses at low levels sufficient to develop resistance to other infections . Some viruses protect humans against infection by other pathogenic viruses . For example , latent ( non-symptomatic ) herpes viruses can help human natural killer cells which are a specific type of white blood cell , identify cancer cells and cells infected by other pathogenic viruses . They arm the natural killer cells with foreign substances known as antigens which cause immune responses in the human body that will enable them to identify tumour cells .
This is both a survival tactic by the viruses to last longer within their host , and to get rid of competitive viruses to prevent them from damaging the host . In the future , modified versions of viruses like these could potentially be used to target cancer cells .
There are viruses such as Pegivirus C or GBV-C that do not cause clinical symptoms . Studies have shown that HIV patients infected with GBV-C live longer in comparison to patients without it . Pegivirus C slows disease progression by blocking the host receptors required for viral entry into the cell and promotes the release of virus-detecting interferons and cytokines – proteins produced by white blood cells that activate inflammation and removal of infected cells or pathogens .
Modern technology has enabled us to understand more about the complexities of the microbial communities that are part of the human body . In addition to ‘ good ’ bacteria , we now know there are beneficial viruses present in the gut , skin and even blood .
Cynthia concludes her article by noting that " Our understanding of this viral component is largely in its infancy . But it has huge potential in helping us understand viral infections , and importantly , how to fight the bad ones . It could also shed light on the evolution of the human genome , genetic diseases , and the development of gene therapies ." RACA
www . hvacronline . co . za RACA Journal I November 2020 35