A short history from Karelia study to biodiversity and public health interventions

Abstract

Contact with natural environments enriches the human microbiome, promotes immune balance and protects against allergies and inflammatory disorders. In Finland, the allergy & asthma epidemic became slowly visible in mid 1960s. After the World War II, Karelia was split into Finnish and Soviet Union (now Russia) territories. This led to more marked environmental and lifestyle changes in the Finnish compared with Russian Karelia. The Karelia Allergy Study 2002-2022 showed that allergic conditions were much more common on the Finnish side. The Russians had richer gene-microbe network and interaction than the Finns, which associated with better balanced immune regulatory circuits and lower allergy prevalence. In the Finnish adolescents, a biodiverse natural environment around the homes associated with lower occurrence of allergies. Overall, the plausible explanation of the allergy disparity was the prominent change in environment and lifestyle in the Finnish Karelia from 1940s to 1980s. The nationwide Finnish Allergy Programme 2008-2018 implemented the biodiversity hypothesis into practice by endorsing immune tolerance, nature contacts, and allergy health with favorable results. A regional health and environment programme, Nature Step to Health 2022-2032, has been initiated in the City of Lahti, EU Green Capital 2021. The programme integrates prevention of chronic diseases (asthma, diabetes, obesity, depression), nature loss, and climate crisis in the spirit of Planetary Health. Allergic diseases exemplify inappropriate immunological responses to natural environment. Successful management of the epidemics of allergy and other non-communicable diseases may pave the way to improve human and environmental health.

Keywords: Karelia Allergy Study; allergy epidemic; allergy programme; asthma; biodiversity hypothesis; climate change; nature loss; non-communicable diseases.

Figure 1

Upper light microscopical picture shows normal bronchial epithelium (L = lumen, C = ciliated cells, G = goblet cells). Thin arrows show the basement membrane (BM). Lower picture shows bronchial epithelium (E) from a patient with newly detected asthma. There Is edema fluid between epithelial cells, BM Is swollen, and the tissue under BM (lamina propria) is full of eosinophils (black dots) (, modified).

Figure 2

Left panel, asthma prevalence in the Finnish conscripts 1926–1989 (21). Two lower curves indicate percentages of men exempted at call-up medical examination because of asthma (closed circles), and those discharged during course of the service (open circles). Right panel, generational increase in positive allergen specific IgE levels to birch pollen in the Finnish but not in the Russian Karelia (22). Among older generations, born in the 1940s, the prevalence was at the same low level in Finnish vs. Russian Karelia. Adopted from Ref. (5).

Figure 3

Drinking water in schools and house dust at homes contained much more microbes in Russian vs. Finnish Karelia and provided protection against allergy in Russia (42, 43). Photos: Tuula Petäys.

Figure 4

Nature step to health — Lahti regional health and environment programme 2022–2032. The action plan combines disease prevention and actions for environmental sustainability (80).

Figure 5

Health wheel going around. From the disaster of World War II to great acceleration with population explosion, urbanization, and changes of environment and lifestyle. Overuse of natural resources has kept the wheel going but is causing climate crisis and nature loss with major health impact. Coming around to ongoing military conflicts in Europe and elsewhere denotes great slowdown.