[Lepidopterism due to the butterfly Hylesia nigricans. Preventive research-intervention in Buenos Aires]

A preventive research-intervention against the butterfly Hylesia nigricans was performed after an increase in spontaneous reports of nonspecific dermatitis in El Pato neighbourhood, Berazategui County, Buenos Aires Province. The overall pre-intervention incidence was estimated with a semistructured questionnaire carried out during March 2001. The trees in the street were sprayed with Bacillus thuringiensis, and the insecticide effect was evaluated both in the field and in the laboratory (November 2002). The impact was estimated with a post-intervention questionnaire during March 2002. The age distribution, clinical appearance, persistence (11 days) and seasonality (January-February 2001) of the cases were consistent with dermatitis due to H. nigricans. The mortality of larvae 96 h after the spraying was 100%. The incidence rates before and after the intervention were 10.3% y 1.8% respectively. The coordinated action of National, Provincial and District oficials allowed to identify the problem, to design an operational research, and to perform a preventive control strategy transferable to the community.