How the microbial environment affects susceptibility to asthma or food allergy has become a primary area of modern allergy focus.
At the 2018 American Academy of Allergy, Asthma & Immunnology (AAAAI) and World Allergy Joint Congress in Orlando, FL, comparisons between extreme urbanization with poverty in the barrios of Caracas, Venezuela, and the very rural areas of South Africa compared to neighboring more typical urban environments, were presented by Arnoldo Capriles Hulett, MD, from Caracas, Venezuela and Michael Levin, PhD, Head of Division of Asthma and Allergy at University of Cape Town, respectively.
Social context must be taken into consideration when developing guidelines for managing asthma and food allergy (FA), Hulett said. Approximately 80% of the total Caracas, Venezuela population lives in areas of extreme poverty known as barrios. Hulett pointed out that rural communities in the United States are currently trending negatively, while its urban populations continue to rise. These urban environments tend to have a much greater incidence of food allergy and aeroallergen sensitization.
Thorough clinical analysis revealed that exposure to allergens at less than 1 year of age leads to tolerance, while initial exposures occurring during 2-3 years of age led to a sensitization.
In particular, Hulett’s studies reveal that exposure to bacterial phyla bactericides or firmicutes can lead to protection against atopy and recurrent wheezing. Interestingly, some of the beneficial bacteria are carried in the gut of cockroaches. Moreover, a steady cumulative exposure lead to less sensitization.
Hulett stressed that the social context must be taken into consideration when considering simple but effective treatment options. He described the dramatic affect that the timing of inhaled steroid administration has on effectiveness in the prevention of asthma exacerbation.
Researchers observed that administration of inhaled steroids at 5:30 PM was effective at increasing peak expiratory flow rate in asthmatics, but when steroids were administered at 8:00 AM it was completely ineffective.
Levin noted that in his research of rural South African environments, there is exceptional microbial diversity, less IgE, less lower airway hyper-responsiveness, and less sensitization compared urban populations. He highlighted several distinguishing characteristics of rural South African life: boiling instead of frying, less maternal smoking, lower infections other than tuberculosis, less soft drinks, and more vegetables.
Food allergies have been on the rise for all races over the past decade in the United States.
Mahboobeh Mahdavinia, MD, PhD, an assistant professor specializing in allergy and immunology at Rush University in Chicago, has been examining factors affecting racial differences influencing the risk for food allergies and asthma.
African Americans in particular have a 2.5-fold greater chance for developing asthma and a 1.8-fold greater chance for developing eczema, but ironically have a lower chance of receiving a FA diagnosis compared to white children.
Mahdavinia examined differences in healthcare management in African Americans versus white residents. Approximately 50% are on Medicaid, as compared to just 10% of white residents.
Analysis of food sensitivities revealed that individuals with egg or dairy allergies were much more likely to be asthmatic than those without these sensitivities. Other sensitivities did not correlate with susceptibility to asthma. Consistent with this observation, the race with the greatest susceptibility to asthma — African Americans — also have the higher likelihood for egg or dairy food allergies amongst the 3 examined races.
Her examination of racial food allergies revealed that Hispanics are more susceptible to corn sensitivity, while African Americans were more likely to be sensitive to wheat. Interestingly, she noted, these are exactly the foods most eaten by the respective races.
Mahdavinia summarized that African Americans and Hispanics report much higher rates of atopic conditions than white Americans. What’s more, food allergies from different races have different profiles.
She stressed programs designed to educate families with food allergy conditions — in a manner tailored their socioeconomic background — are critical moving forward.