AbstractAbout 80 fishermen affected by the mysterious skin disease in November 2021. A similar outbreak was identified around the same time, in the same area among fishermen the previous year. The seasonality (both outbreaks occurring during the same month of consecutive years), demographics of cases (fishermen in certain area), and spread (no household contacts) is not explained by viral infections with either monkeypox or chickenpox. This suggests a possibility of non-infectious cause such as toxin exposure. However, visual inspection of skin lesions and patient interviews may not be sufficient. Laboratory testing is required to rule out orthodox virus as a cause of this outbreak and further rigorous study of other causes beyond infection should be considered.