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Atopy and malaria
B Lell1, S Borrmann, M Yazdanbakhsh
1Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon. bertrand.lell@uni-tuebingen.de
Insights
Reduced childhood exposure to malaria parasites may protect against allergies. This study suggests that higher Plasmodium falciparum exposure is linked to a lower risk of developing atopy, challenging the hygiene hypothesis.
Area of Science:
- Immunology
- Epidemiology
- Tropical Medicine
Background:
- Allergic diseases have increased globally.
- The hygiene hypothesis suggests reduced childhood infections contribute to this rise.
- The relationship between parasitic infections and atopy requires further investigation.
Purpose of the Study:
- To investigate the association between Plasmodium falciparum exposure and atopy in children.
- To explore the potential protective role of malaria against allergic sensitization.
Main Methods:
- A 5-year cohort study of 91 children in Gabon.
- Tracking malaria incidence and conducting skin-prick tests for mite antigen.
- Utilizing survival analysis to assess risk factors.
Main Results:
- 18% of children showed a positive reaction to mite antigen.
- Children with atopy had fewer infections and lower malaria incidence.
- High Plasmodium falciparum exposure correlated with a significantly lower risk of atopic skin reactions (p=0.001).
Conclusions:
- Low exposure to malaria parasites may lead to immune dysregulation and increased allergy risk.
- Parasitic infections, like malaria, might offer protection against allergic diseases by modulating immune responses.
- Understanding the interplay between parasitic infections and allergy can inform new prevention strategies.
Abstract:
The last decades have seen a dramatic rise in the prevalence of allergic diseases throughout the industrialised world. The "hygiene hypothesis" postulates that this is due to a reduced exposure to infections during childhood. A cohort study in children from Gabon gave us the unique opportunity to examine the relationship between exposure to P. falciparum and atopy. 91 children, who had been closely followed for an average of 5 years and of whom the exact incidence of malaria attacks was known, underwent a skin-prick test with mite antigen. 16 children (18%) had a positive reaction. Gender or age had no effect on the outcome of the test. However, those tested positive had had less infections and a lower incidence of malaria than children tested negative (p = 0.017). Survival analysis shows that children with a high exposure to P. falciparum were at lower risk of an atopic skin reaction (p = 0.001). We postulate that the low exposure to the malaria parasite contributes to the development of an imbalanced immune system with a subsequent higher reactivity to the allergen tested. Immuno-suppression is commonly seen during a malaria attack and this correlates positively with the level of anti-inflammatory cytokines such as interleukin-10. High exposure to parasite antigens might counterbalance pro-inflammatory immune reactions and thus protect against allergic diseases. A better understanding of the relationship between parasitic infection and allergy will help us to develop strategies to prevent allergic disease without being exposed to infectious diseases.