Mosquitoes spike as UAE's desert 'greening' creates perfect conditions for bugs

Scientists have urged UAE residents to remain “vigilant” in combating the threat of disease posed by mosquitoes, as new 'green' desert communities create perfect conditions for bugs to thrive.

Researchers said some species of the small insect were thriving in the Emirates due to increasing urbanisation, leading to a higher number of potential breeding grounds.

Stagnant pools of water often found on buildings sites are ideal for adult females to lay their eggs.

And specific species can carry viruses which can represent a threat to both humans and animals.

Dr Jeremy Camp, of the Institute of Virology at the University of Veterinary Medicine in Vienna, said it was important to have “continued surveillance” of mosquitoes and, in particular, a “vigilant” approach to detect the viruses they carry.

“For the public, the best thing to do is to get rid of standing water in your house and around your garden,” he said.

“These are really easy measures which can protect you and your family from being annoyed by mosquitoes, and the risk of getting a mosquito-borne virus.”

In a recent study in the UAE, researchers set mosquito traps at two artificial wetland areas at Al Qudra Lakes and Ras Al Khor Wildlife Sanctuary in Dubai.

Further traps were also placed at Al Ain Zoo, Al Ain Oasis, Lake Zakher - an artificial lake in Al Ain - and Wadi Wurayah National Park in Fujairah.

Mosquitoes are insidious, and species such as Aedes aegypti [which transmit the Dengue virus] are notorious for sneaking into countries unnoticed until it’s too late

Dr Jeremy Camp

The traps were baited with dry ice - which emits carbon dioxide just as humans do when we exhale - and attracts mosquitoes.

The insects which were caught were first frozen and then sent to a laboratory for identification.

During collecting sessions from January to February and from April to May last year, 1,142 mosquitoes from 10 species were collected.

Five had never been recorded in the UAE before, although previous studies had identified them in Saudi Arabia and Iran.

At the more urban locations, while fewer species were caught, some appeared to be thriving, possibly due to higher instances of stagnant water.

However, researchers found few “anopheline” mosquitoes – a genus which carries malaria – and this success was put down to an eradication programme first launched in the Emirates in 1970.

Scientists also found that more than 700 of the mosquitoes were from the species Culex perexiguus, which lives widely in the Arabian peninsula.

Using genetic testing, two mosquito-borne viruses were detected - the Barkedji virus and Bagaza virus - in this species.

An outbreak of Bagaza virus in Spain in 2010 killed pheasants and partridges, although the virus does not harm people.

Speaking to The National, Dr Camp, lead author of the study which was published in the UK-based journal Parasites and Vectors and co-written by researchers at Dubai Municipality and the Mohammed Bin Rashid University of Medicine and Health Science in Dubai, said that C. perexiguus was potentially benefiting from man-made water sources in the Emirates.

His paper also warned that efforts to irrigate the desert in parts of the UAE may lead to the creation of even more water sources where mosquitoes can breed.

C. perexiguus mainly feeds by sucking the blood of birds, and in other countries it transmits West Nile Virus, which can be deadly to people. This virus was not, however, detected in the Emirates.

Mosquitoes regularly spark concern in the country, with authorities, such as the waste management company Tadweer, receiving thousands of calls annually from residents requesting mosquito populations be sprayed with bio pesticides.

In June last year Tadweer, in collaboration with Abu Dhabi Food Control Authority and Abu Dhabi Farmers’ Services Centre, launched an awareness campaign.

Farmers were urged to remove stagnant water from ponds and water tanks, and to keep them covered. Homeowners were advised to prevent water from accumulating in containers such as plant pots.

Dinesh Ramachandran, UAE health and safety manager for Rentokil, said even small pockets of water could contain as many as 1,000 mosquito larvae. He said the company was dealing with mosquito-related call-outs “pretty much every day” in the UAE.

“We get calls from residential clients, resorts, hotels, commercial properties, including buildings under construction,” he said.

“Standing water is an invitation to mosquitoes. If you have buckets outside or children’s toys, anything that can collect water, we would want that emptied.”

Dr Camp said the health ministry and other authorities are working hard to keep mosquito populations under control.

He said the study found no mosquitoes which posed a threat to humans but indicated there was no room for complacency.

“Mosquitoes are insidious, and species such as Aedes aegypti [which can transmit the Dengue virus] are notorious for sneaking into countries unnoticed until it’s too late,” he said.