THAUMETOPOEA-PITYOCAMPA CATERPILLAR AND MAN - MORPHOLOGY OF VENOM APPARATUS - EPIDEMIOLOGICAL INVESTIGATION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 106  (10) , 769-778
Abstract
The combination of a mechanical phenomenon (penetration of the hair) and a chemical phenomenon (discharge of a toxic substance) accounts for the pathological symptomatalogy induced by the processional pine caterpillar. Epidemiological study delineated the regions infested by the pine caterpillar and described the dermatitis inflicted by this caterpillar with special emphasis on frequency of ocular lesions. A close correlation was noted between the geographical density of the populations of T. pityocampa Schiff and the geographical density of the clinical cases recorded. Skin tests confirmed that the urticant substance was histamine-liberating. A morphological study of the urticant apparatus of this caterpillar (mirror and urticant hairs) was undertaken with the scanning electron microscope. The progressive placement of the bristles on the cuticular pads of the mirror was followed during the last 3 larval stages (L3, L4 and L5). The urticant hair, hollow on the inside, carried pointed spikes directed towards its distal end. There was no hole or pores on the hair and the necessity to grind the bristles to extract the urticant substance suggested that the hair was a bulb which must be broken in the skin in order to release its urticant substance (histamine-liberating).