Two Photosensitive Dermatitis Outbreaks Caused by Cordierites frondosus - Chuxiong Yi Autonomous Prefecture, Yunnan Province, China, 2023.

What is already known about this topic?: Cordierites frondosus (C. frondosus) is a species of toxic mushroom known to induce symptoms of photosensitive dermatitis.

What is added by this report?: In the months of May and June 2023, a total of four patients in Chuxiong Yi Autonomous Prefecture, Yunnan Province, were affected by C. frondosus poisoning, occurring over two distinct incidents. The condition of two patients deteriorated after they were re-exposed to sunlight on the seventh day following the initial poisoning. Separately, an additional two patients reported experiencing a mild, needle-like sensation on areas of their skin exposed to the sun, recorded on the twelfth day subsequent to the poisoning.

What are the implications for public health practice?: Given that symptoms of photosensitive dermatitis, a potential severe consequence of C. frondosus poisoning, can manifest up to a week post-sun exposure, it is advisable to avoid sunlight for a minimum of two weeks following poisoning.