Access or non-access to tap water is an important risk factor for spread of mosquito causing vector-borne dengue disease, according to an international study, making the case for ensuring potable water in every household.

“Greater use of water storing containers in tap-water deprived densely populated urban areas of the national capital could be potential  dengue-virus-spreading mosquitoes breeding ground,” said the study published in journal PlOS Neglected Tropical Diseases.

The researchers found that tap water access was notably lower in socially disadvantaged areas.

The lack of access to tap water likely results in more water bearing container stores in homes that could breed mosquitoes due to the storage of clean water in jars, said the researchers after conducting random survey of houses, which showed that the most deprived areas also had poorest water access and had the highest proportion of containers positive for mosquitoes.

Hence, improved access to tap water could lead to a reduction in dengue risk, not only for those who are directly affected but also for the general population, said the researchers in the study, “ Social and environmental risk factors for dengue in Delhi city: A retrospective study”

Scientists, including researchers from the National Institute of Malaria Research in Delhi, measured dengue antibodies in 2,107 individuals and mosquito larval prevalence in 18 areas within Delhi. They also analysed social and environmental risk factors for the virus.

Of the tested individuals, 160 were positive for dengue virus antibodies, indicating a recent or current infection.

Colonies with less than 61 per cent having access to tap water had higher abundances of mosquito larvae, suggesting a higher risk of dengue. Despite better infrastructure and lower mosquito densities, wealthy colonies had a higher risk of recent infection than the poor ones.

The researchers report that infected commuters who move into high-income areas during the day import the dengue virus to the wealthy areas, contributing to that higher risk.

However, despite relatively low mosquito densities, they said wealthy colonies had a higher risk of recent infection than intermediary colonies.

The scientists believe this may likely reflect the import of dengue virus by commuters coming into the high income areas during the day.

They said close to 3.5 billion people across the world are at risk of dengue viral infection which is spreading increasingly with growing rates of urbanisation.