ACAAI 2011: Looking at Parasites' Roles in Allergies
NOVEMBER 05, 2011
BOSTON—The incidence of allergic disease has risen 50 percent each decade since the 1960s, according to Phillip Lieberman, MD, FACAAI, Clinical Professor of Medicine and Pediatrics in the Departments of Internal Medicine and Pediatrics (Divisions of Allergy and Immunology) at the University of Tennessee College of Medicine. Lieberman spoke at the American College of Allergy, Asthma & Immunology’s annual meeting this morning.
Prehistoric people experienced no allergies, he said, and today’s anthropomorphic societies also report no allergic disease. The first mention of hay fever came in 1918 with the Industrial Revolution. Today, one in every 13 kids in the United States has a food allergy according to an article published in the Memphis Commercial Appeal.
His own experience with atopic asthma led Lieberman to question whether, when there’s such a high rate of incidence, the cause could really be abnormal.
“The epidemic is inversely related to the incidence of parasitic infection,” Lieberman said. “The same mechanism that produces the allergic response also defends against parasitic infection. The type of infection is key.” Acute infection up-regulates allergy while chronic infection down-regulates allergy.
Lieberman said that parasites don’t want their host to die; rather, parasites want their host to house it for a long period of time. Therefore, “the parasite must secrete a substance which downgrades our ability to expunge it. If an acute infection is expunged, you up-regulate allergy and if the infection remains, you down-regulate allergy.”
Immunologic overspill, Lieberman said, now plays a role in suppression. “Immunomodulation and suppression by flarial nematodes … although antigen specific, has…spread to unrelated third-party antigens…and thus can have a broad impact on the whole immune system. These overspill reactions … suppress allergies,” he quoted. (Parasite Immunology Vol. 27). A study in children in Caracas found that a prescription for worms increased allergy sensitization. After 22 months, the children had a total IgE decline, and skin test reactivity and rast to aeroallergens increased. Reactivation of parasite infection reversed the process. Another study, he said, found that populations with no allergies but positive skin test have a high incidence of parasites.
J.A. Turton published his own experience with parasites in Lancet in 1976. Turton self-inflicted a hookworm infection to cure hay fever and was successful, Lieberman said. The literature mounted and by 2009, people were paying thousands of dollars for parasites.
“If we have atopy and no helminths, the genes increase incidence in all allergy and asthma disease,” Lieberman summed up. “If we don’t, there is a decline in incidence.”