In early May 1981 thousands of hospital admissions due to a rare disease which presented high mortality rates were recorded.

On 10 June 1981, a public announcement about the causal agent of the epidemic was made. This finding coincided with the epidemic curve having reached its peak and initiated a slow decrease. Some days later, an exchange of the suspect oil with pure olive oil was initiated by the Government to prevent that more people were affected.

Women were more affected than men; above all, those of less than 40 years who presented a higher mortality risk by TOS along the years.