The Role of Helminth Infection and Environment in the Development of Allergy: A Prospective Study of Newly-Arrived Ethiopian Immigrants in Israel

Abstract

Helminth infection may be protective against allergy and account for the low prevalence of allergy in developing countries. We studied prospectively the prevalence of allergy in Ethiopian immigrants with heavy helminth infection on arrival in Israel, and again after a year of adjustment to an urban industrialized setting, to explore the roles of helminth infection, changed environment and background immunity on the manifestations of allergy. 126 newly arrived Ethiopian immigrants were studied at baseline and 115 after a year of follow up in Israel. Allergic symptoms, Skin prick tests (SPT), Tuberculin (PPD) skin tests, stool and blood samples were obtained for determining parasites, blood IgE and eosinophil levels, respectively. Anti-helminthic therapy was offered to the entire infected individuals, but only 50/108 (46.3%) took the medication. At baseline, there was a significant negative association between helminth infection and allergy, 4/18 (22.2%) of uninfected participants were allergic compared to 7/108 (6.5%) of helminth-infected participants (p = 0.028), as well as between helminth infection and SPT reactivity, 12/18 (66.6%) of uninfected participants compared to 43/108 (39.8%) of helminth-infected participants (p = 0.033). After one year, a significant general increase in allergy and SPT was observed. While only 11/126 (8.7%) were allergic at baseline, 30/115 (26.1%) became allergic at follow-up (p<0.0001), and while 55/126 (43.7%) were SPT+ at baseline, 79/115 (68.7%) became SPT+ at follow-up (p<0.001). A twofold increase in allergen sensitization was also observed after one year in Israel, particularly for dust mites, grasses and olive tree (p<0.001). These results show that: a) Helminth infection is significantly associated with low allergy and low SPT reactivity; b) One year after immigration to Israel, allergy and SPT reactivity increased significantly in all immigrants; c) Higher increases in positive SPT and allergy were observed after a year in the group that remained infected with helminths, even though they had a lowered helminth load; d) The reasons for the increased allergy one year after immigration needs further investigation but probably reflects the combined influence of the decreased helminth load and novel environmental factors.

Risk factors for asthma among schoolchildren who participated in a case-control study in urban Uganda

“…These findings are comparable to observations from Europe showing that children born on a farm (usually in rural areas) have a lower risk of asthma in later life, even when they subsequently moved to urban areas (27), and that children who migrated to Europe after age five had a lower prevalence of asthma, similar to their country of origin, than children who were either born in Europe or migrated before the age of five (28,29). However, there are also studies that show increased risk of wheezing and allergy among children following migration (30,31). Unlike studies from Europe and North America which have reported a lower risk of asthma for children born or raised on farms (32,33), our study found no association between asthma risk and exposure to farm animals either during pregnancy or in early life.…”

Influence of Parasitic Worm Infections on Allergy Diagnosis in Sub-Saharan Africa

“…Recently, Stein and colleagues examined the burden of helminth infections among 126 immigrants from Ethiopia newly arrived in Israel and related these to allergy outcomes [ 20 •]. The most prevalent helminth infection detected was hookworm (73.1%) followed by S. mansoni infection (47.2%) [ 20 •].…”

“…One year post-anthelmintic treatment, an increase in allergy symptoms was observed in treated individuals. Stein et al 2016 [ 20 •] …”

The Association Between Interleukin-10 Gene Polymorphism And Il-10 Levels In Geohelminth Positive Adolescents And Adults In West Sumatera

“…Geohelminth can cause nutritional disorders and anemia, especially in children with less nutritional intake [2]. Behind these negative effects, worms turned out to provide protective effects on some diseases such as allergies, which have been proven by many researchers [3,4,5]. This turned out to be related to the ability of worms to modulate the immune response of the host [6,7].…”