A Sydney allergy practice has found an 'overwhelming majority' of a group of patients who developed a rare allergy to red meat had previously had an adverse reaction to tick bites.
Clinical Immunologists, Drs Sheryl van Nunen and Suran Fernando and colleagues, of Royal North Shore Hospital, found that 24 of 25 patients who presented with a history of allergic reaction to red meat also reported large local reactions to tick bites.
"Seventeen of the 25 had a severe reaction to the bite, such as tongue swelling, throat constriction or shortness of breath," Dr Fernando said.
Patients then reported that they had previously been bitten by a tick, resulting in a painful, itchy lesion greater than 50mm that lasted at least a week.
"All of the patients lived in Sydney's northern beaches area, which is endemically infested with several tick species.
They all described the culprit as a hard-bodied tick shaped like a human fingernail ranging in size from 3 to 10 mm. This is most likely to be Ixodes holocyclus
,commonly known as the paralysis tick, which is "not only the most commonly found species that affects humans in the area, but is also the species most associated with hypersensitivity reactions in humans".
The researchers set up a retrospective control, contacting 29 patients from the clinic with allergies to foods other than red meat residing in the same region. All 29 reported a history of tick bites without subsequent reaction.
"The findings suggest that, in our patient population, the overwhelming majority of people with the relatively rare condition of red meat allergy are preceded by sensitization to tick bites," Dr Fernando said.
Further research is needed, but it could be that "individuals are sensitized to tick salivary proteins that are cross-reactive with proteins found in various red meats".
"To determine the true prevalence of this cross-reactivity, a prospective study could examine consecutive patients who are bitten by ticks (with and without reactions) for the subsequent development of red meat allergy."