"People with the metabolic disorder glucose-6-phosphate dehydrogenase deficiency (G6PD) should also avoid quinine."

https://www.livescience.com/36536-tonic-water-quinine-malaria-health.html

"Oxidative Stress is known to compromise the health of the human body. Any stimuli (trigger) that cause oxidative stress could possibly bring on an attack of Acute Hemolytic Anemia to those who are G6PD deficient."

"SICKNESS such as a cold or influenza is known to start the onset of G6PD deficiency symptoms."

https://g6pddf.org/g6pd-deficiency/what-to-avoid/

"G6PD deficiency is most prevalent in Africa, where it can affect up to 20 percentof the population. The condition is also more common in men than in women."

https://www.healthline.com/health/glucose-6-phosphate-dehydrogenase-deficiency