Question: Which epidemiological pre-cursors are required for the development of clinical favism?
Answer: The cited reference notes “Favism occurs commonly only where the frequency of G6PD deficiency is relatively high and where fava beans (also known as broad beans) are a popular food item (https://readtiger.com/img/wkp/en/Broadbean_Yield.png), which reflects its bifactorial nature. This is true, for instance, in southern Europe, in the Middle East, and in Southeast Asia but not, for example, in northern Germany, where fava beans are grown but G6PD deficiency is rare, or in West Africa, where G6PD deficiency has a high prevalence but fava beans are not grown. (Luzzatto L and Arese P. Favism and glucose-6-phosphate dehydrogenase deficiency. 2018 NEJM 378:60-71)