Doctors urge caution as standing floodwater in UAE could pose health risks

Waterborne conditions and illnesses passed on by mosquitoes are a threat, according to experts

Flooding in the Al Barsha area of Dubai. UAE residents should be aware of the health hazards standing water can pose. Chris Whiteoak / The National

As the UAE recovers from the flooding caused by the most severe rains in the country’s history, risks can remain beyond damage to infrastructure.

Doctors and researchers say problems can arise from contaminated water, or when insects that lay their eggs in standing pools increase in number.

Some areas of the country recorded more than 250mm of rain in 24 hours, leading to severe flooding that caused disruption and took days to dissipate.

Heavy rains often flood sewerage systems, which can result in an increase in rates of viral or bacterial illnesses that cause diarrhoea or vomiting, said John Oxford, emeritus professor of virology at the University of London and author of a textbook titled Human Virology.

"If there’s a huge amount of water moving around, that gets into the sewage system," he said.

"If your house is flooded and there’s a couple of feet of water, the sewage system is going to be flooded into the general environment.

Mosquitos can lay eggs in the standing rainwater, prompting a surge in numbers in the aftermath of bad weather. Reuters

"If the sewage system is compromised … it will move into the garden and the next-door neighbour. Pretty soon everybody’s system is mixing with everybody else’s."

Conditioned for illness

Conditions such as typhoid, a potentially lethal illness caused by bacteria, are among those that may spread as a result of contaminated water, Prof Oxford said.

While such contaminated water does pose a risk, Dr Bharat Pankhania, a senior consultant in communicable disease control and a senior clinical lecturer at the University of Exeter in the UK, said that areas may not remain hazardous for long.

"[The UAE] has strong sunshine. That’s a lifesaver in that strong sunshine is a very good steriliser of bacteria and viruses," Dr Pankhania said.

Another key concern is that mosquitoes may lay eggs in standing water left behind by the rain, which could result in increased rates of disease.

"In stagnant water microbes and mosquitoes can breed," Dr Pankhania said. "You can have an upsurge in the population of mosquitoes."

Among the mosquito-spread diseases found in the UAE is dengue fever, a viral condition that causes fever, headache, vomiting and other symptoms, and for which immediate medical help is recommended.

Dengue fever is one condition that the US Centres for Disease Control and Prevention (CDC) warns can become more common after extreme weather.

The CDC says that the types of mosquitoes that spread viruses may become more common about a fortnight after a hurricane.

Disease spread from mosquitoes may take several more weeks to develop, according to the CDC.

The risks, the organisation says, are greater in areas that have received more rainfall than usual but have not actually flooded.

Dr Pankhania said that while some mosquitoes spread disease, many do not and so pose no risk of infection.

In the US and in US territories, for example, the CDC reports that there are more than 200 types of mosquitoes, but only a dozen spread pathogens.

While there could be an increase in some diseases, doctors say that the UAE is unlikely to see the emergence of illnesses that are not normally present at all.

"You will not get things you didn’t get before, but you can have more of what you used to have a few of before," Dr Pankhania said.

So conditions including malaria, which is not considered to be a threat in the UAE, are unlikely to emerge as a result of this week’s flooding.

Ian Jones, a professor of virology at the University of Reading in the UK, said that much of the floodwater in the UAE was likely to disappear fairly quickly.

That reduces the threat of mosquito eggs hatching to produce larvae that turn into pupae and then adult mosquitoes.

Dumped tyres or building sites are often seen as potential breeding grounds for mosquitoes, as they can contain standing water, but given that the UAE’s rainfall burst is not likely to be sustained for weeks, the dangers are lower.

"If it was constant flooding and it was likely to last for a month, it would be a different case," Prof Jones said.

"It will probably dry up pretty quickly. It has to be sitting out there for some time [to pose a risk]."

Emirates Health Service recommends the removal of standing water and covering water tanks to reduce dangers.

It also suggests wearing long-sleeved clothes and the use of insect repellants.