Mapping Allergic Diseases in Sub-Saharan Africa
Ofilia Mvoundza Ndjindji
Joel Fleury Djoba Siawaya- Service Laboratoire, Unité de Recherche et de Diagnostics Spécialisés, Centre Hospitalier Universitaire Mère-Enfant, Fondation Jeanne EBORI (URDS-CHUMEFJE), Libreville, Gabon
The consensus is that allergic diseases are increasing in Africa. However, this paradigm shift has not yet been translated into practice. Focused on infectious diseases (malaria, tuberculosis, HIV), health policies in Sub-Saharan Africa have often neglected the diagnosis and management of allergies. Allergic disease mapping is crucial to grasp the full extent of Africa's allergic diseases' impact. This mapping will require diverting resources to diagnose and study allergies, even more at the dawn of precision medicine.
Typology of Allergens Sensitization in Africa
In constant increase globally, allergies and allergic diseases are no longer “a rare fact” in Africa as we thought (1, 2). The International Study of Asthma and Allergies in Childhood Phase III that included 16 African countries (Algeria, Cameroon, Congo, Congo (RDC), Ethiopia, Gabon, Ivory Coast, Kenya, Morocco, Nigeria, Reunion Island, South Africa, and Tunisia) (1) and a systematic review based on data from 11 African countries (including Botswana, Democratic Republic of Congo, Ghana, Kenya, Morocco, Mozambique, Nigeria, South Africa, Tanzania, Tunisia, and Zimbabwe) (2), highlight that allergies are emerging disease in Sub-Saharan Africa. In 1999, a study realized on suspected allergy cases in Côte d'Ivoire showed that 56.4%, 30.7%, 23.5%, 8.5%, 2.8%, and 1.4% were, respectively, sensitized to mites, cockroaches, molds, pets' danders (dog and cat), foods (rice, peanut, and soy) and latex allergens. In addition, 52% of cases were polysensitized (3). More than a decade later, studies done in Ghana and Cameroun confirmed the hierarchy of allergens in the sub-Saharan context, with mites (51%), cockroaches (59%), pets' danders (15%), and foods related allergies (8%) as the main allergens (4, 5). High sensitization of Africans to mites (5–11), and cockroaches (5, 7, 8, 10) has been reported in many studies. Moreover, it is essential to emphasize that most studies on hypersensitivity to allergens have been carried out in the context of asthma.
Food allergies are not as well-documented as mites, cockroaches, or even pets' dander allergies. Nevertheless, existing data suggest that the burden of food allergies in Africa should not be neglected or undermined. Food allergies represent 5% to almost 50% of allergic reactions in Africa (2, 12–14).
Allergies Diagnosis and Investigation in Patients Suspected of Allergic Diseases in Africa
Existing studies revealed that a limited number of studies on allergies in Africa are based on precise diagnostic testing. Most studies reflect self-reported symptoms or prick-test-based sensitization to food, which raises the question of the reliability and precision of the reported data. For example, a study in Ghana clearly showed the gap between reported adverse reactions to foods and the results of allergy tests. Indeed, 11% of participating children reported adverse reactions to foods, and only 5% showed a positive allergy test (13). Moreover, the skin prick test widely used to diagnose and investigate allergies in Africa has a limit. Its limit resides in the fact that a positive person may have been just sensitized rather than genuinely allergic (14). In addition, most of the time, allergies diagnosis is solely based on medical records and do not involve confirmatory test.
Precision Medicine Prospect in Africa
Regardless of the disease, every patient may have different clinical features, treatment responses, and disease outcomes due to genetic, epigenetic, and environmental factors. Precision medicine, a patient-tailored disease treatment approach, requires appropriate biomarkers and tools to guide the diagnosis and define disease endotypes (15). A stringent and precise diagnostics is required for the better care of allergic patients (16).
To take up the challenge of precise medicine or simply improve the care of allergic patients, Sub-Saharan Africa should develop capacities to diagnose and investigate allergies with precision. Mapping allergic disorders in the African context and implementing precise diagnostic tools will provide essential information for implementing the first and most simple personalized care of allergic subjects. Indeed, the first advice to patients with allergic disease is to avoid exposure to allergens that induce symptoms of their disease. To give that advice, one should identify with precision the disease-causing allergens. Also, mapping and characterizing allergic disease endotypes in the African context would probably help achieve precision medicine in Africa's allergic diseases. First, however, fundamental questions need to be answered in mapping allergic disease endotypes in sub-Saharan Africans.
1. Is highly melanized skin, which protects black people from the effects of sun UV-rays, influence UV-rays' activation of vitamin D?
2. Is vitamin D deficiency in African populations a critical risk factor for developing allergic diseases?
3. What are the biochemical characteristics (micro-environment) of asymptomatic sensitized people and others that progress to allergy etc.?
4. What is the real influence of parasitic worm infections on allergy and its diagnosis in Sub-Saharan Africa?
Concluding Remarks
Allergy research and capacity building need to be scale-up in Africa to provide the most effective diagnosis, disease monitoring, and patient care for those affected.
Author Contributions
OM and JD conceptualized the topic and wrote the manuscript. Both authors approved the submitted manuscript.
Conflict of Interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher's Note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Acknowledgments
We want to acknowledge CHU Mère-Enfant for its support. We also give our thanks to Irène Machiro Mwatsama for her critical proof reading of this manuscript.
References
1. Ait-Khaled N, Odhiambo J, Pearce N, Adjoh KS, Maesano IA, Benhabyles B, et al. Prevalence of symptoms of asthma, rhinitis, and eczema in 13- to 14-year-old children in Africa: the International Study of Asthma and Allergies in Childhood Phase III. Allergy. (2007) 62:247–58. doi: 10.1111/j.1398-9995.2007.01325.x
2. Kung SJ, Steenhoff AP, Gray C. Food allergy in Africa: myth or reality? Clin Rev Allergy Immunol. (2014) 46:241–9. doi: 10.1007/s12016-012-8341-z
3. Ngom Abdou KS, Koffi N, Blessey M, Aka-Danguy E, Meless T. Allergies respiratoires de l'enfant et de l'adulte en milieu africain. Approche épidémiologique par une enquête de prick-test. Revue Franç Allergol Immunol Clin. (1999) 39:539–45. doi: 10.1016/S0335-7457(99)80116-6
4. Stevens W, Addo-Yobo E, Roper J, Woodcock A, James H, Platts-Mills T, et al. Differences in both prevalence and titre of specific immunoglobulin E among children with asthma in affluent and poor communities within a large town in Ghana. Clin Exp Allergy. (2011) 41:1587–94. doi: 10.1111/j.1365-2222.2011.03832.x
5. Pefura-Yone EW, Kengne AP, Afane-Ze E, Kuaban C. Sensitisation to Blattella germanica among adults with asthma in Yaounde, Cameroon: a cross-sectional study. World Allergy Organiz J. (2014) 7:22. doi: 10.1186/1939-4551-7-22
6. El Fekih L, Mjida M, Souissia Z, Ben Hmida A, El Gueddari Y, Douaguie H, et al. Étude de la sensibilisation aux 3 acariens (Dermatophagoïdes pteronyssinus, Dermatophagoïdes farinae, Blomia tropicalis) au Maghreb et en Afrique subsaharienne dans une population de patients consultant pour une rhinite et/ou un asthme. Revue Franç Allergol. (2014) 54:107–12. doi: 10.1016/j.reval.2014.01.033
7. Oluwole O, Arinola OG, Falade GA, Ige MO, Falusi GA, Aderemi T, et al. Allergy sensitization and asthma among 13–14-year-old school children in Nigeria. Afr Health Sci. (2013) 13:144–53. doi: 10.4314/ahs.v13i1.20
8. Seedat RY, Claassen J, Claassen AJ, Joubert G. Mite and cockroach sensitisation in patients with allergic rhinitis in the Free State. South Afr Med J. (2010) 100:160–3. doi: 10.7196/SAMJ.3669
9. Potter PC, Berman D, Toerien A, Malherbe D, Weinberg EG. Clinical significance of aero-allergen identification in the Western Cape. South Afr Med J. (1991) 79:80–4.
10. Kwizera R, Wadda V, Mugenyi L, Aanyu-Tukamuhebwa H, Nyale G, Yimer G, et al. Skin prick reactivity among asthmatics in East Africa. World Allergy Organiz J. (2020) 13:100130. doi: 10.1016/j.waojou.2020.100130
11. Pefura-Yone EW, Kengne AP, Kuaban C. Sensitisation to mites in a group of patients with asthma in Yaounde, Cameroon: a cross-sectional study. BMJ Open. (2014) 4:e004062. doi: 10.1136/bmjopen-2013-004062
12. Gezmu AM, Kung S-J, Shifa JZ, Nakstad B, Brooks M, Joel D, et al. Pediatric spectrum of allergic diseases and asthma in a tertiary level hospital in botswana: an exploratory retrospective cross-sectional study. J Asthma Allergy. (2020) 13:213–23. doi: 10.2147/JAA.S253618
13. Obeng BB, Amoah AS, Larbi IA, Yazdanbakhsh M, van Ree R, Boakye DA, et al. Food allergy in Ghanaian schoolchildren: data on sensitization and reported food allergy. Int Arch Allergy Immunol. (2011) 155:63–73. doi: 10.1159/000318704
14. Gray CL. Food Allergy in South Africa. Curr Allergy Asthma Rep. (2017) 17:35. doi: 10.1007/s11882-017-0703-4
15. Muraro A, Lemanske RF Jr, Castells M, Torres MJ, Khan D, Simon H-U, et al. Precision medicine in allergic disease-food allergy, drug allergy, and anaphylaxis-PRACTALL document of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology. Allergy. (2017) 72:1006–21. doi: 10.1111/all.13132
Keywords: mapping-allergies, allergy-diagnosis, allergens, precise-medicine, Africa
Citation: Mvoundza Ndjindji O and Djoba Siawaya JF (2022) Mapping Allergic Diseases in Sub-Saharan Africa. Front. Allergy 3:850291. doi: 10.3389/falgy.2022.850291
Received: 07 January 2022; Accepted: 27 January 2022;
Published: 17 February 2022.
Edited by:
Gabriele Gadermaier, University of Salzburg, AustriaReviewed by:
Amir Hamzah Abdul Latiff, Pantai Hospital Kuala Lumpur, MalaysiaCopyright © 2022 Mvoundza Ndjindji and Djoba Siawaya. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Joel Fleury Djoba Siawaya, joel.djoba@gmail.com