Blood-sucking ticks that trigger a bizarre allergy to meat in the people they bite are exploding in number and spreading across the US, to the extent that they could cover the entire eastern half of the country and infect millions of people, experts have warned

“We’ve seen an explosive increase in these ticks, which is a concern. I imagine alpha-gal will soon include the entire range of the tick, which could become the entire eastern half of the US as there’s not much to stop them. It seems like an oddity now but we could end up with millions of people with an allergy to meat.”

Alpha-gal is a confounding condition because it doesn’t cause an immediate allergic reaction, unlike a peanut allergy, with symptoms often appearing several hours after consuming meat. The syndrome is not caused by a pathogen but spurs an allergy to a sugar molecule found in mammals and an array of other things, from toothpaste to medical equipment. Researchers think the condition can wane over time but is also worsened by further tick bites.

Dairy, another mammalian product, is also off limits. “I’ve learned what I can eat now, but I was so sad when I realized I couldn’t have pizza again, I remember crying in front of a frozen pizza in the supermarket aisle,” she said.

Lone star ticks are aggressive and can speedily follow a human target if they detect them. “They will hunt you, they are like a cross between a lentil and a velociraptor,” said Sharon Pitcairn Forsyth, a conservationist who lives in the Washington DC area.

A particular horror is the prospect of brushing up against vegetation containing a massed ball of juvenile lone star ticks, know as a “tick bomb”, that can deliver thousands of tick bites. “They are so tiny you can’t see them but you have to take it seriously or you’ll never get them off you,” said Forsyth, who now carries around a lint roller to remove such clusters.

Symptoms can also be alarmingly varied – Forsyth said she rarely eats out now because of concerns of contamination in the food and even that alpha-gal could be carried to her airborne, via the steam of cooked meat.

“Some people are scared to leave the house, it’s hard to avoid,” she said. “Many people who get it are over 50, so the first symptom some of them have is a heart attack.”

The spread of alpha-gal comes amid a barrage of disease threats from different ticks that are fanning out across a rapidly warming US. Powassan virus, which can kill people via an inflammation of the brain, is still rare but is growing, as is Babesia, a parasite that causes severe illnesses. Lyme disease, long a feature of the US north-east, is also burgeoning.

“There’s a tremendous urgency to confront this with new therapies but the problem is we are going backwards in terms of funding and support in the US. There have been cuts to the CDC and NIH (National Institutes of Health) which means there is decreasing support. It’s a major concern.”