Stored water in Nairobi rife with disease-causing fungi

A common adage says still waters run deep. Often-times, it means that a mild exterior manner may hide a more passionate or dangerous internal nature.

This statement has been qualified by a study showing that stored water is a rife breeding ground for some of the common-disease causing fungi and yeast in Nairobi City County.

The two-year study by the Kenya Medical Research Institute (Kemri) collected samples across households in Nairobi and makes a startling conclusion that more care is needed when handling stored water.

“Most of these fungi that build up in form of slime (scientifically referred to as biofilms) are spread to human beings through direct or indirect contact with water. Along with related user practices, water storage often using tanks/vessels is envisaged to be a source of water contamination," said Ms Olga Mashedi,  a research scientist and lead researcher of the study that is yet to be published.

“Fungi is a ubiquitous silent killer and over time, the continuous dose effect we get from consuming or using fungi infested-water results in build-up of fungi in our bodies, which exposes us to diseases,” explained Ms Mashedi.

“Think of the washing machine. Once used and the rubber ring not cleaned, it becomes a breeding ground for fungi, which will grow and form a network like that of a root system.”

Many households in Nairobi are not connected to a piped water system, therefore relying on storage tanks and containers to store fetched water for later use.

But what many people are oblivious to is the fact that by storing the water over a long period of time, it is prone to contamination with fungi. 

These fungi, Ms Mashedi added, are responsible for allergies, opportunistic infections like ring worms and athlete’s foot, mainly to immune-compromised patients, and even cancer.

Between 2019 and 2021, 120 water samples were collected from stored containers in households across the county.

The pathogens

Other studies show that water storage tanks do harbour several pathogens that cause different diseases. Waterborne illnesses caused by bacteria found in contaminated household water storage tanks increases the risk of spreading waterborne diseases and may lead to many infectious outbreaks.

From the study presented at this year’s Kemri’s annual scientific and health conference in Nairobi, yeasts species were the most common species isolated from water species in a collective of one or more types of microorganisms that can grow on many different surfaces known as biofilm. As such, the role they play needs to be further investigated,  said Ms Mashedi,

Yeasts are single-celled microorganisms that are classified along with moulds and mushrooms, as members of the Fungi family. In the study, Aspergillus species, a common mould that lives indoors and outdoors, were more frequently isolated type of fungi. 

For many years, attention has been focused on both access to and quality of water, but while access to safe water has significantly improved worldwide, quality appears to be further declining and it has been deteriorating more than proportionally to the economic and population growth.

Good quality water is one that has acceptable chemical, physical, biological and radiological characteristics, based on local and widely-acceptable international standards, such as the World Health Organization  standards.

“Little is known about the optimal tank and/or vessel cleaning frequency to ensure safe drinking water quality,” said Ms Mashedi.

“For now, avoid storing water for a long period of time like more than a month. Clear and clean your tanks regularly,” she advised.

She said there is need for lab analyses to include fungi in the panel of pathogens when determining water contamination because fungi is fast becoming an emergent problem.

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