Wellies being replaced by flipflops is as sure a sign as any that British summertime has finally arrived. According to the Met Office, torrential rain will be replaced by clear blue skies for much of August, but news that we can expect to be basking in high temperatures and slathering on the sunscreen comes with something of a sting in the tail. Last week it was reported that, thanks to unprecedented warm and humid weather conditions, mosquito populations are soaring in the UK. Holiday-makers in Norfolk claim to have been severely bitten by the pesky parasites, as do people living in places as far-flung as North Wales and South Devon.

For an insect more commonly associated with more exotic places to have landed on our doorsteps might seem inconceivable to many. In fact, floods or no floods, mosquitoes can usually be found somewhere in the UK. A survey being carried out by the London School of Hygiene and Tropical Medicine (LSHTM) is monitoring mosquito levels in, of all places, Barking, in Essex, an area where their prevalence is unusually high.

According to the researchers, Barking’s sewage plant in Beckton, among the largest in Europe, is a prime breeding ground for mosquitoes, which spread and reproduce in the local community. “Some people in Barking sleep under mosquito nets because there can be so many,” says Chris Curtis, a professor of medical entomology at the LSHTM. “But levels there do not seem to have increased recently.”

Is this less than welcome arrival from the tropics a cause for concern? Not necessarily. Curtis says recent reports that there has been a sharp rise recently in mosquito numbers are speculation. He suggests that it is unlikely that they would have proliferated so soon after Britain’s monsoon-like conditions. “We know that mosquitoes need wet places to breed and we know that puddles have formed, which are the ideal places for them to reproduce,” he says. “But the cool nights we have in the UK mean that it would take several weeks for numbers to rise, if indeed they rise at all.” Besides, adds Curtis, the variety of mosquito that might breed more rapidly in the UK is called the culex, and is “definitely not the type of mosquito that can cause malaria”.

Although a preventable disease, around 2,000 travellers return to the UK each year with malaria contracted in countries where it is endemic, including Africa, Central and South America and Southeast Asia. Worldwide, malaria kills three million people a year. Transmitted through the bite of the female anopheles mosquito, malaria thrives when mosquitoes have warm temperatures and stagnant water for breeding. The disease has not been common in Britain since the late 1880s – before that, it was endemic in parts of Kent and Essex – and was eradicated from many other parts of Europe at least a decade ago.

“What many people don’t realise is that mosquitoes are not born carrying malaria,” Curtis says. “The insects get malaria parasites – called plasmodium – only if they bite an infected person.” At present, he adds, it is highly unlikely that an outbreak would occur in countries such as the UK that have effective healthcare and medical systems.

However, some scientists believe that global warming is influencing the spread of the disease to areas that have not been affected for years. Statistics from Kenya have shown that mosquitoes are now carrying malaria in Nairobi, the capital, and other areas that until recently had not been hit. It is thought that variable weather conditions, including rising temperatures combined with high rainfall, are to blame.

Closer to home, malaria has reappeared for the first time since 1945 in countries bordering Europe such as Georgia, Turkey and Azerbaijan. Last summer, a 59-year-old man contracted malaria in Corsica, the first-locally derived case in the area for 35 years. It is thought that he was bitten by one of the carrier mosquitoes that have reestablished themselves in the French Mediterranean region.

At this rate, is it inevitable that malaria will eventually come back to the UK? “There is a possibility,” Curtis says. “If we continue to experience warmer temperatures indecades to come, that will favour the conditions that malaria parasites need to breed. But there is no likelihood of that happening soon.”

More worrying in the short term is the threat of other disease-carrying mosquitoes invading our shores. Among them is the Asian tiger, which became established in Italy in 1990 and has since been sighted in southern France, Belgium, Switzerland and Spain. So far it has not been spotted here, but it has been identified by the Health Protection Agency (HPA) as “an insect that could potentially arrive in the UK”.

Named for its white stripes on its legs and thorax, the Asian tiger doesn’t carry malaria but has been shown in laboratory trials to be a successful disease bearer, or “vector,” for the transmission of illnesses such as encephalitis, Dengue fever and yellow fever in humans, as well as dog heartworm. It breeds in anything that holds water, including flowerpots, tyres, tin cans and clogged-up guttering. It is widespread in the US, having been transported to Houston, Texas, around 1985 via a shipment of tyre castings from Japan. The mosquitoes quickly swept up the coast of southeastern America, transported mostly in scrap tyres. Unlike some other mosquitoes, it is not deterred by sunshine so will hunt by day as well as at night. As a result, it bites more often than more common mosquitoes do.

“The Asian tiger is a very efficient species that spreads easily,” Curtis says. “It is possible that it will come to the UK, but we don’t know yet how much of a nuisance it will be.”

In 2006 a study by the European Centre for Disease Prevention and Control gave warning that EU countries were increasingly at risk from another serious mosquito-borne infection, chikungunya, carried by the aedes species of the insect. Chikungunya is highly debilitating, causing fever, headaches and severe joint pain. Indeed, the disease derives its name from the Swahili for “that which bends up”, in reference to the stooped posture of sufferers.

Last year the viral illness hit the island of Réunion, in the Indian Ocean, afflicting more than 50,000 people. There have also been outbreaks in Mauritius, Madagascar and the Seychelles. Cases from mainland India were also on the rise last year, with more than a million reported. The HPA says the number of travellers returning to the UK with evidence of exposure to the fever rose to 93 by last August from an average of 6 in previous years. On Réunion 77 deaths were linked directly or indirectly to the disease.

Sir William Stewart, the HPA’s chairman, stresses the importance for travellers “to follow the usual health advice on how to avoid being bitten by mosquitoes and other insects”. But Curtis says anyone planning a holiday in the UK needn’t panic: “Our evenings are too cool for mosquitoes to flourish. They’ll be around, but not to a dangerous extent.”

How to beat the bugs

1. Get rid of any unnecessary water containers in the garden. Change birdbath water once a week and keep pools stocked with fish

2. Avoid using patio heaters. Mosquitoes aren’t so much attracted to body heat as to carbon dioxide. Patio heaters are a magnet

3. The three Ds: use DEET-based insect repellent, dress in long sleeves and trousers, don’t spend too much time outdoors at dusk or dawn

4. If mosquitoes bite you at night, spray the room with insecticide in the evening to kill any that may have entered during the day

5. When camping, use mosquito nets impregnated with an insecticide

6. If you are travelling to a country where malaria is endemic, seek advice from your GP or travel clinic. Antimalarial products vary depending on where you are going, because malarial parasites differ from country to country – no one medication suits every destination.

7. The Health Protection Agency and Chartered Institute for Environmental Health have a monitoring scheme, Mosquito Watch.

For information go to cieh-npap.org.uk/policy.asp