Outbreak of methanol poisoning at a rural community in Southwest Nigeria: Results of laboratory analysis

Abstract

Background: In the month of April 2015, an epidemic initially attributed to mysterious causes broke out in a rural community (Ode-Irele, Ondo State) of Nigeria. Twenty-five adults were affected, with a mortality of 18/25 (a rate of 72%). This is a report of laboratory analysis conducted at the College of Medicine, University of Ibadan, and the University College Hospital, Ibadan, Nigeria. Methods: Samples of blood and urine (both coded A, B, and C) of the three victims of the disease, and three plastic containers of locally brewed alcoholic beverages (coded (D, E, F) reported to have been consumed by the victims were made available. All the samples were tested for copper, lead, zinc, and cadmium toxicity. The blood samples were tested for cholinesterase inhibition as an indirect test of probable pesticide poisoning. Methanol content of the samples was determined by gas chromatography. Results: The urine and blood samples showed concentrations of lead, copper, zinc, and cadmium that were not uncommonly elevated. Zinc levels in the blood of two of the victims were low. There was a significant inhibition of cholinesterase activity in the three blood samples as follows; sample A 96.2%, sample B 31.8%, and sample C 2.5%. Methanol content of the alcoholic beverages ranged from 48 g/L (4.8%) to 625 g/L (62.5%), far above allowable limits of 0.005 g/L (0.0005%) in Nigeria. Conclusions: Methanol poisoning was concluded to be the cause of the unknown disease. This finding guided measures that rapidly controlled and eventually ended the epidemic.