Drinking water at risk
By Andre Bagoo Monday, November 7 2011
APPROXIMATELY 14 percent of potable water in this country has tested positive for the gastro-intestinal illness-causing organism, crytosporidium, according to the latest report of the United Nations Development Programme (UNDP).
According to the 2011 UNDP Human Development Report–released this month–19 percent of water tested positive for the single-cell organism after periods of heavy rainfall.
The disclosure is made in the context of the report’s discussion of the impact of climate change on small island developing states.
“Salt water intrusions are increasing due to sea level rise and frequent coastal flooding, further contaminating ground water wells, the primary fresh water source for its rapidly growing population,” the report states.
“About 19 percent of potable water in Trinidad and Tobago following heavy rainfall tested positive for cryptosporidium, a diarrhoea-causing parasite,” the report details.
“Similarly, dengue fever has a clear association with rainfall and temperature in the Caribbean.”
Cryptosporidium is a single-cell parasite which has gained much attention within the last 20 years. It causes cryptosporidiosis, a kind of chronic diarrhoea.
Little is known about the pathogenesis of the parasite, and no safe and effective treatment has been successfully developed to combat cryptosporidiosis.
Unlike other intestinal pathogens, cryptosporidium can infect several different hosts, can survive most environments for long periods of time due to its hardy coating.
The UNDP report ranks this country at number 62 on its ratings of human development, up one spot from last year’s report.
In relation to the contamination of water, the UNDP report cites a series of studies, dating from 2006 to 2010, but does not specifically identify which study discloses the statistics about Trinidad and Tobago.
However, a 2008 study published by UWI and WASA researchers made findings and recommendations in relation to cryptosporidium levels in Trinidad and Tobago.
Approximately 18 percent of samples collected from watersheds in the country had, according to the study–published in the Journal of Water and Health–positive results. Maraval had the highest percentage of positive samples, whereas Aripo had the lowest.
“The high percentage of positive samples from Maraval may be due to the discharge of sewage effluent at the uppermost site,” the researchers suggested.
“The public health risk associated with the high prevalence of cryptosporidium oocysts...in a stream feeding an urban drinking water supply can be significant.”
Researchers noted that, “A survey of 181 sewage treatment plants in Trinidad, for example, found that only 28 percent were functioning satisfactorily and that a number were spewing improperly treated sewage onto roadways, footpaths and watercourses.”
“The implications for the health of the public, especially high-risk groups such as the immuno-compromised are significant. When the diversity of the socio-cultural uses of
untreated surface waters by the population is considered, what becomes obvious is that there is a multitude of routes/opportunities for infection.
The main route of concern for the present study, treated drinking water, was shown to be a potential transmission route,” researchers noted.
“Cryptosporidium oocysts, ubiquitous in surface waters in Trinidad, may have multiple environmental sources on the island with urban and wildlife sources being the most important.”
The researchers concluded that, “A significant human health risk is posed by leakage of inadequately treated sewage effluent into surface waters which are used for contact recreation and for potable water.
“Thus, management of the risk of cryptosporidium infection through contact or ingestion of affected water should focus on the functioning and operation of sewage treatment plants, particularly those located upstream of water treatment plants and recreational sites.”
However, wildlife was also a potential source of contamination.
“The contribution of wildlife is significant. Control of contamination of water sources by this route is an impossible task; thus, management of this risk to human health from wildlife must be undertaken at the water treatment plant and the resource/user interface,” the researchers recommended.