‘Alarming presence’ of three enteric viruses in the capital’s sewage water created the risk of the viruses getting released in the environment putting public life in danger.
Although it is certain that sewage water contains enteric viruses, the high presence of Rotavirus, Norovirus and the Adenovirus responsible for causing diarrhea and intestine infection, found a study jointly done on the capital’s water by Nihon University School of Medicine in Japan and Dhaka University baffled the scientists.
They said bacterial diarrhea caused by Vibrio cholerae, Eschericia coli, Salmonella, Shigella and Camphylobacter are more prevalent in Bangladesh and the high presence of these pathogenic viruses could double the risk of such enteric diseases hazarding thousands of life.
‘An alarming situation of possible outbreaks of these viruses and bacteria has been feared here,’ said Sheikh Ariful Hoque, the lead author of the study on ‘Alarming situation of spreading enteric viruses through sewage water in Dhaka city: Molecular epidemiological evidences’.
The study was published in the International Journal of Food and Environmental Virology in the March issue.
Arif told New Age that the study, first ever about analyzing virus presence in environment in Bangladesh, would help the policy makers to take action to rectify sewage water management.
Right now, the capital is witnessing unusually high diarrhea infections.
In April alone, ICDDR,B treated 23,864 patients mostly from the capital and the adjacent districts.
At ICDDR,B, most of the diarrhea patients are suffering from rotavirus, shigella, salmonella and e-cli.
ICDDR,B chief of hospital Azharul Islam Khan told New Age that the trend of diarrhea patients flow indicates that problem lies in the water and the environment.
‘The water supply system is responsible for the high number of diarrhea patients,’ he said, adding, ‘we are afraid there are high concentration of diarrhea causing virus and bacteria in the environment in the capital.
Echoing Azhar, Arif said that the Bangladesh capital might witness diarrhea outbreaks in the coming years unless the sewage water system was improved.
For the study, raw sewage water samples were collected from five open road-side drains in the central part of the capital, three beside sewage lines of three hospitals and two at residential areas. The samples were collected from each location once every month from June 2016 to May 2017.
The study revealed that 93 per cent of water samples contained these viruses.
In particular, 76 per cent samples were positive for Adenovirus, followed by 53 per cent Norovirus and 38 per cent Rotavirus.
Arif said viruses are not uncommon in sewage water but such high presence of these viruses indicates that the system of managing the sewage water is not good posing huge risk of spread of these viruses in human system through consumption and other uses.
He said that the Bangladesh capital’s untreated sewage water was often drained into rivers or canals resulting in using contaminated water for washing, bathing, swimming, irrigation crops and so on and so forth.
Again, overflow of sewage water remains a common dangerous scenario during the rainy season.
The contaminated sewage water often seeps into the water supply pipelines as well.
The Dhaka Water Supply and Sewerage Authority admitted that it cannot treat the sewage water that often seeps into water supply pipelines.
Currently, DWASA operates only one sewage treatment plant to treat only 20 per cent of generated sewage of the city, while the remaining 80 per cent is drained out through open shallow-surface drains mostly not connected to storm sewer, therefore ultimately drained into the rivers.
Though some people use under-ground septic tanks for dumping toilet waste, while clearing the pit they often discard the waste indiscriminately in open water bodies.
Again, most of the open drains overflow during the monsoon submerging roads and low lying areas.
Arif said that since the Bangladesh capital remains the most crowded city in the world, its inadequate sewerage and sanitation system poses huge threat to the environment and public health.
He said in Bangladesh, prevalence of viral diarrhea remains 32.8 per cent for Rotavirus, 25 per cent for Norovirus, and 10.7 per cent for Adenovirus.
These fecal-orally transmitted infections are mostly associated with consumption of contaminated water and food and sewage is a major source of disseminating fecal-orally transmitted enteric viruses in the environment.
Arif said though adult people’s risk of death due to infection by the viruses was not that severe, the children were the most vulnerable group.
‘About 45,000 children die in Bangladesh annually for using or drinking contaminated water,’ he said.
Asked for comments Health Services deputy director for communicable disease control, Dilruba Sultana, told New Age that diarrhea cases in the capital were mostly caused by bacteria and the evidences of viruses presence in sewage water increased the burden of concern.
She said coordinated efforts were needed as the CDC department alone could not tackle such an alarming situation.
DWasa technical director Shahid Uddin said the study only confirmed their own assumptions that sewage water containing viruses and bacteria end up in the environment putting public health in high risks.
He admitted that the sewage water were not treated before release as DWASA had no capacity to do more with only one sewage treatment plant.
‘The lone sewage treatment plant constructed in 1978 in a corner of the city, Pagla sewage treatment plant, cannot treat the sewage produced every day,’ he told New Age.
Shahid said DWASA had plans to solve the problem by 2025.
He said four other treatment plants would be set up at different zones.
Source: New Age.