The UK is facing an exponential increase in bedbug infestation as a result of this summer’s hot weather, which is exacerbating a major problem in densely populated cities, experts are warning.

In higher temperatures, the reproductive cycle of the bugs – Cimex lectularius – shortens from 18-21 days to eight or nine days, according to David Cain, of extermination company Bed Bugs Limited.

The problem is compounded by social stigma which often results in a reluctance to seek help, and because a significant proportion of the population have no physical reaction to bedbug bites so may be unaware of an infestation. “The problem has been spreading globally since the late 1990s, and there is literally no country on the face of the planet that hasn’t had a bedbug problem,” said Cain.

“In the UK there has been a year-on-year increase since 2006, which shows no sign of plateauing,’” he added. “And in the next month or two, we will see a ramping up of activity related to the higher temperatures, which make breeding massively more efficient.”

Tony Lewis, head of policy at the Chartered Institute of Environmental Health, said the persistent bedbug presence in the UK was made worse in the summer by higher temperatures and people returning from holiday with bedbugs in their luggage. “It doesn’t matter if they’ve been staying in a five-star hotel or a dingy B&B, the chances of encountering bedbugs are equal,” he said.

Bedbugs – flat, rust-coloured parasites about 5mm long – were common in the UK 100 years ago, but their numbers were greatly reduced by the use of insecticides such as DDT. Now, the bugs have developed resistance to chemical treatments, making the eradication harder.

Their source of nourishment is human blood. “This insect has developed to be the most efficient and adaptive hunter of human beings that we’ve probably ever had,” said Cain. “If people are fearful of sharks, the answer is to stay out of the water. When it comes to bedbugs, the answer is to be permanently on guard.”

Jacqueline Smith, a London professional in her 30s who didn’t want her real name used, had been scratching her arms and legs for about a month before she summoned professional help last week.

“I was waking up every morning with bites which I thought were from mosquitoes, although no one else was suffering. My boyfriend mentioned bedbugs, but I completely dismissed it. In my mind, bedbugs were found in crusty backpackers’ hostels in other countries – I didn’t think it could happen to us,” she said.

When she finally lifted her mattress to find a handful of bugs crawling beneath it “I cried. I was totally repulsed and panicked”.

Bedbugs can leave irritating bites, but a significant number of people have no reaction. Photograph: Getty

She is now in the middle of a 14-day programme of eradication and monitoring, which involves washing bedding and clothes at 60 degrees, and a deep clean of the couple’s bedroom. Her partner’s office has been identified as a potential source. Cain said: “Bedbugs can happen to anyone. I’ve been into some awesome Knightsbridge apartments where behind the front door there’s a massive bedbug problem. Lots of people equate bedbugs with dirt, but dirt has nothing to do with it.”

Most people carried the bugs home with them from public transport or workplaces, he said. Bedbugs were commonly found in seats on London buses and tubes, but there were particular “hubs and spokes”.

“There’s a west-to-east corridor that follows the Central line. There’s another hotspot running from Elephant and Castle down to Lewisham and New Cross. And yet another from Elephant and Castle to Brixton, then Norwood, and then on to Croydon.”

Last month, Air India grounded two planes after passengers in business class complained they had seen bedbugs in their seats. The airline called in exterminators to fumigate upholstery and carpets.

Bedbugs have also frequently been found in hotel bedrooms, even ones as prestigious as the Waldorf Astoria in Manhattan. The Bedbug Registry, which monitors infestations in North America, said there had been a 44% increase in reports of bugs in New York hotels between 2014 and 2015.

Cain inspects every hotel bedroom he books into before unpacking and estimates that 5% are infested. He said: “The only way a hotel can protect itself is to close its doors to guests.”

His advice to the public is: never sit down on buses, trains or tubes; check office chairs, plane seats and hotel mattresses before contact; and monitor and vacuum your bed once a month.

According to Lewis, the growing prevalence of bedbugs is partly because a lack of awareness. “The time was when people regularly aired bedding, and that was partly to do with guarding against pests. No one does that any more. Now when people find bedbugs, there’s a shame, a stigma around it.”This year’s annual Global Bed Bug Summit in Denver, Colorado, heard that the eradication industry could be worth $1bn within five years. But, writing on the news and analysis website The Conversation, one academic, Heather Lynch of Glasgow Caledonian University, has suggested that bedbugs may have become so endemic that people need to learn to live alongside them.

Cain, who left a career in the City to launch Bed Bugs Limited, admitted that he “may have become slightly obsessed” with the pests. Had he ever had an infestation at home? “Yes. An ex refused to follow my advice about never sitting down on public transport. That’s one of the reasons why she became an ex.”

• This article was amended on 19 August 2018 to correct the spelling of the Latin name for bedbugs.