RESUMEN
AIM: This article describes the search for the source of infection after a female dental receptionist was diagnosed with Legionnaires' disease. METHODOLOGY: An environmental investigation was carried out to locate the source of the infection. Samples were taken from different sources at sites where the dental receptionist resided and worked, and tested for Legionella pneumophila. Thermal measures were employed to eliminate the favourable conditions for the growth of Legionellae. RESULTS: The initial sampling of 13 sites indicated that there were four sample points which showed the presence of Legionella. Heat shock treatment of the hot water system was introduced as an intervention measure. A subsequent sampling of 14 sites indicated that two sample points showed the presence of Legionella. Water supply temperatures were found to be within the Legionella spp. ideal growth range. Faults were identified and measures were taken to regulate thermal temperatures outside the range which permits Legionellae growth. CONCLUSION: There is scientific evidence that water used as a coolant and irrigant during dental procedures can be heavily contaminated with micro-organisms. Thermal control of water and measures to correct faulty water systems can assist in prevention of Legionnaires' disease.