Dr. Sharma
A.  Let’s take a closer look at your daughter’s latex allergy to help clarify this. She is allergic to latex because her immune system reacts to a particular protein in latex. That protein is actually very similar in structure to proteins found in several plant foods, such as banana, kiwi, avocado, papaya, chestnut, tomato, potato, and bell pepper. This is called “cross-reactivity.”

So, the immune system might “cross-react” to a plant food that is structurally similar to latex. Based on limited studies, it seems that one-third to one-half of people with latex allergy might have an allergic reaction to one of these plant foods, especially fresh fruits, which is why this is called “latex-fruit syndrome.”

That reaction risk is the reason avoidance of these fruits and vegetables is standard advice for latex allergy.

Dr. Sharma is an allergist, clinical researcher and Assistant Professor of Pediatrics. He is Associate Chief of the Division of Allergy and Immunology at Children’s National Medical Center in Washington D.C. and Director of the Food Allergy Program. He co-authors “The Food Allergy Experts” column in the American Edition of Allergic Living magazine. Questions submitted below will be considered for answer in the magazine.

WE CAN blame the deciduous trees’ attempts at procreation for our watery, red-eyed snuffling and other springtime rhinitis symptoms. Catkins, which often appear as elaborate cones or buds, are a tree’s reproductive organs, and they bloom before the leaves bud. Male catkins will release literally millions of pollen grains into the air in an attempt to find a female catkin match.

Dr. Wilf Nicholls, director of the Memorial University of Newfoundland Botanical Garden, explains that wind pollination is “super inefficient” because only a fraction of the huge amounts of tiny grains the tree churns out will arrive at their intended destination, the female catkin. Instead, great quantities of them will be inhaled into noses and throats and set off reactions in the tree allergic.

It’s an unlucky break that most deciduous trees in northern climes are wind-pollinated. Birch, elm, maple, oak and poplar are some of the most allergenic trees across Canada and the northern United States. But where you are, the month and the weather all influence the onset of symptoms.

West Coast

On the foliage-rich west coast, red alder is public enemy number one. Robert Guy, head of forest sciences at the University of British Columbia, says much of the forest surrounding coastal towns and cities is full of red alder. Depending on the weather, these trees can pollinate as early as mid-February, or as late as the end of March, and they spread pollen for about three weeks.

Vancouver allergist Dr. Donald Stark says red alder is particularly insidious because it produces a ton of pollen; it often has the highest pollen count of any plant on the coast. People allergic to it may also react to birch trees, which pollinate about a month after alders, prolonging the misery.

Stark identifies the Garry oak as another culprit on the west coast.
In most of Canada, ragweed is the worst offender for triggering hay fever, followed by grass, then trees. Stark says the west coast is the exception: here, trees pack the hardest punch.

Next: Traveling Eastward

AS FRIENDS herald spring’s arrival with the glee of a lottery winner, it’s often hard for the allergic to join the celebrating. They know that their tree foes – birch, elm, maple, alder, poplar and their nasty ilk – have begun to churn out clouds of tiny allergy-causing pollen.

Not only do a third of us battle hay fever – with runny noses, sinus and eye symptoms – but for a significant proportion of allergy sufferers, the spring bloom is just the start of their allergy woes. Dr. Antony Ham Pong, an Ottawa allergist and clinical researcher, estimates that up to 10 per cent of the general population has a condition called oral allergy syndrome, or OAS.

It’s a less severe form of food allergy, directly related to pollen reactions, that’s known to set off tingling and unpleasant itching in the mouth, throat and lips. Reactions are caused by a variety of fruits, vegetables, nuts, seeds, and even spices; all of which share allergenic proteins with specific hay fever-causing trees and plants.

“Nobody talks about the foods causing oral allergy syndrome because it’s not considered a life-threatening allergy,” says Ham Pong, the author of several articles educating patients and doctors about oral allergy syndrome. “But it’s actually more common than peanut, milk, egg, and fish allergy.”

In springtime, two of the biggest cross-reaction offenders are birch and alder trees. Depending on where you live, anywhere from 20 to 70 per cent of people who are allergic to birch and alder pollens will also have oral allergy syndrome.

Ham Pong estimates about a third of birch-allergic North Americans are affected, but the incidence of oral allergy syndrome is even higher in some European countries. Although OAS is relatively common, he doesn’t think it is increasing, at least not in North America. Rather, doctors have become better at spotting this condition.

But how can a tall, skinny tree that gives you the sniffles cause an itchy mouth if you chew on a celery stick?

Next: How the immune system gets confused