Sandro Teghini was midway through a cocktail when he realised he had been poisoned. He was starting to boil up and his friend observed that his eyes had gone red.
"I looked down and a rash was coming up on my skin and I thought, 'I'd better get to the bathroom,' and I collapsed," Teghini recalls.
As other revellers in the bar stepped around him like a drunk, he had just enough strength to administer adrenalin with an EpiPen. Then the ambulances arrived.
Teghini's poisons were eggs, milk and peanuts, which he believes were the culprit in his near-death experience, possibly as a result of the cocktail shaker not having been properly rinsed after it was used to shake a nut-based liquor. Growing up in the 1980s, he had been the only anaphylactic at his primary school of 300 students, and the only one at his high school of 1200 students, but the teachers and other parents knew not to expose him to his allergens. Out in the big wide world, he was in danger.
Teghini was riding the crest of what would become an extraordinary surge in childhood allergy.
Hospitalisations due to anaphylaxis have tripled over 13 years, according to research published in the Journal of Allergy and Clinical Immunology this week, and increased more than sevenfold among children aged five to 14.
And where it was once difficult to persuade schools even to accept children at risk of anaphylactic shock, schools are now equipped with EpiPens and teachers trained to use them.
"It's become almost an epidemic," Rob Loblay, director of the allergy unit at Royal Prince Alfred Hospital, says.
"About 1991, '92 we started noticing an increase in kids coming here with food allergy, particularly peanut allergy, and that escalated through the '90s. By the end of the 1990s, we were getting flooded."
But though researchers can pinpoint almost to the date when the allergy rate began to swell, there is still no consensus on its cause. Theories spin around clues.
Why has the rise in allergy been so dramatic in relation to peanuts and tree nuts, but to not eggs and milk? Why do the Australian-born children of Asian parents have higher rates of allergy? And why does its prevalence increase with distance from the equator?
In 1989, epidemiologist David Strachan observed during a study of 17,000 British children that the more older siblings a child had, the less likely they were to develop hay fever and eczema.
He hypothesised that those children were more likely to have contracted infections from their older brothers and sisters, either in early childhood or while they were in the womb, and that these infections protected them from subsequently developing allergies.
His thesis, known as the "hygiene theory", became the dominant explanation for the rise in childhood allergy and elements of it are still popular among researchers.
Murdoch Children's Research Institute professor Mimi Tang, who co-authored the latest research, prefers the more nuanced "microbial hypothesis", which holds that people's immune systems are programmed by their exposure to microbes, especially in utero and during the first few years of life. The greater the diversity of bacterial species to which they are exposed, the better the immune function.
But over the quarter century people in Western countries have been exposed to fewer bacterial species – perhaps as a result of diet, the elimination of certain diseases, the prevalence of antibiotics or a more indoor lifestyle. And some people's immune systems have become dysfunctional, overreacting to non-harmful substances.
"Maybe what's been happening is we've had a dwindling over time and then we've reached a critical threshold that's now unmasked a serious vulnerability," Tang says.
"What we do know is the environment in Western lifestyles seems to be an important factor increasing the rise of all allergies, including food allergy."
But it's not clear exactly what it is about the modern lifestyle that is to blame.
"The environment, probably the bugs, the whole way we live, the diet, the sunlight, everything, we don't know."
Other research indicates that Vitamin D may play a role in bolstering the immune system to prevent people from developing allergies. Several studies indicate that people are more more prone to anaphylaxis the further they live from the equator. A 2009 study mapped the locations of 69,000 Australian children who were prescribed allergy medication or specialised infant formula. It indicated that prevalence was higher in the southern part of Australia. Hobart had six times the number of children at risk of allergy than Cairns.
In the United States, EpiPen prescriptions are twice as prevalent in the northern states than the southern states, with the highest rate in Massachusetts and the lowest in Hawaii.
Both these theories would explain to some extent why children born to Asian parents in Australia have higher rates of allergy. They may have a genetic predisposition to allergy, but if they spend their early years in Asia they benefit from the increased vitamin D or other factors inherent to the environment such as a greater range of parasites
"When they live in their own country there are environmental factors protecting them and then when they come over here that environmental protection is lost and they have even higher rates than Australian residents," Tang says.
One of the most contested theories is diet, and specifically the age at which infants are exposed to certain foods. A study published in the New England Journal of Medicine in February found infants who were exposed to peanuts between the ages of four and 11 months were far less likely to develop an allergy that those who were not exposed until the age of five. The finding turned conventional wisdom on its head – previously the American Academy of Paediatrics recommended withholding peanuts from children at risk of allergies until they were three. A month later, colleges of immunology around the world united to call for infant-feeding guidelines to be changed to recommend introducing peanuts earlier in life.
"The fact that there's so many theories and so few answers suggests it's probably a combination of factors," ProfessorRichard Loh, president of the Australasian Society for Clinical Immunology and Allergy, says. The fact that African children living in Australia were developing allergies in their pre-teen years but their parents had never seen it suggests that it is more environmental than genetic, he says. "But people have looked at it and no one's been able to find any one thing."
The society will next month release a national allergy strategy that sets out a long-term plan for managing allergic disease, which will have implications for industries such as hospitality and even airlines.
"This issue really requires leadership, it requires politicians to acknowledge there has been a boom in allergies," Loh says. "If I said diabetes has tripled in 15 years people would say, 'We need to do something'."
As patients are progressing into adolescence, their allergies are causing them headaches of a more embarrassing kind. Loh now advises his teenage patients to ask their dates what they have been eating before they consider locking lips.
"Five per cent of young adults have moderate to severe allergies," Koh says.
"It's not really great on a hot date that you throw up or you have to go to an emergency room. So you have to give them the skills to communicate."
Observing the allergy landscape from one of the state's busiest allergy clinics, Loblay believes the dramatic rise is also attributable to the changes in the way people have been exposed to triggers. Two-thirds of his patients are now allergic to multiple nuts and not just peanuts, a trend that has risen. He also observes that while peanuts are eaten boiled or raw in Asian or African countries where allergy is rare, here they are roasted at high temperatures.
"Roasting temperature may be part of the story," he says. "I have a suspicion, although there's no hard evidence about it yet, that over the last 20 years food manufacturers that produce snacks have been roasting nuts at a higher temperature. The higher the temperature, the higher the flavour."
The problem with the hygiene theory for him is that it doesn't explain why there has been an increase in nut allergies, but not in allergies to other food.
But it's the changing demographic of people with food allergies that is now concerning immunologists, as the allergy generation is growing up, leaving school and venturing into cafes, restaurants and bars.
Two such patients in their late teens or early 20s presented at the Royal Prince Alfred Hospital after going into anaphylaxis on planes last year, both of whom had eaten pesto pasta on domestic flights. Pesto contains pine nuts.
"A lot of effort has been put into educating teachers and school staff and parents in learning how to manage anaphylaxis," Loblay says.
"What hasn't happened yet is any effort to increase awareness in the community generally, because these kids are going to leave school and they are at great risk of allergic reactions."
Like so much of his life at the forefront of the allergy generation, Sandro Teghini's experience may be a portent of the health crisis to come.
