Development of a Legionella spp. Surveillance and Control Model for Hotels in Thailand's Tourist Cities

Abstract

This study aimed to examine the situation of Legionella contamination and environmental health management practices, develop a surveillance and control model, and to formulate policy recommendations for Legionella prevention and control for hotels in tourist cities. The study samples consisted of Type 3 and Type 4 hotels. Quantitative data on outbreak occurrence and Legionella management were collected from 463 hotels using structured survey questionnaires. Qualitative data were obtained through water sampling for Legionella detection, questionnaires, and pre - post assessments of prevention and control measures. Focus group discussions and stakeholder consultations were conducted with representatives from 50 hotels and relevant sectors. Data were analyzed using descriptive and inferential statistics. Data collection was conducted between February and August 2025. The results showed that 263 hotels responded to the survey (56.8%), including 194 Type 3 hotels (73.8%) and 69 Type 4 hotels (26.2%). Among 176 hotels that conducted Legionella testing, 21 hotels (11.9%) reported positive Legionella findings, with tap water identified as the most frequently contaminated water source. Overall, 56.5% of hotels had established prevention plans, while 48.7%had implemented control measures; however, systematic monitoring and evaluation of these measures remained limited. Water sampling from 50 hotels detected Legionella in 14 hotels (28%) during the first survey and in 5 of the 14 positive hotels (35.7%) during follow-up sampling. Hot water from showerheads was the most commonly contaminated source. The temperature of contaminated hot water ranged from 37.0 to 50.0 °C, whereas free residual chlorine concentrations in contaminated cooling tower water and potable water systems ranged from non-detectable to 2.15 mg/L. Compliance with the Department of Health guidelines before the first and second rounds of water sampling was associated with effective reduction of Legionella contamination. Significant improvements were observed in the maintenance of cooling towers, potable water systems, and hot water systems following implementation of the intervention (p < 0.05). The proposed 3R2P Model provides a practical framework for strengthening Legionella surveillance and control in hotel settings. Policy recommendations include establishing a centralized surveillance and reporting system, promoting effective Legionella control technologies, developing national regulations and standardized guidelines, and strengthening intersectoral collaboration to support integrated policy implementation.