Determination of Legionella Spp Prevalence in Hot Springs, Lakes, Hospitals and Drinking Water Distribution Systems in Ethiopia
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Date
2020-06-06
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Addis Ababa University
Abstract
Legionnaires’ disease is an emerging atypical pneumonia type of illness caused by inhalation of aerosols contaminated by Legionella Spp. There is limited information about the prevalence of Legionella Spp., from Ethiopian water systems. A cross-sectional descriptive study which entails the quantitative investigation of Legionella spp from Hot Springs, Lakes, hospitals and drinking water distribution Systems was conducted from Dec 14, 2016, to June 20, 2018. Representative water and biofilm samples collected and analyzed following standard procedures. 1L of water samples was concentrated by membrane filtration techniques by using 47 mm diameter cellulose membranes with a pore size of 0.2μm, microbes retained by the filter transferred to a sterile test tube containing distilled water and further eluted from the filter by vortex-mixing for 5-10 minutes. Biofilm samples were collected from water distribution system by sterilized Dacron Tipped swabs by rubbing three to four times inside water pipe. For Legionella isolation, about 0.1 ml of filtered and biofilm samples were spread plated on Buffered Charcoal Yeast Extract Agar, while Plate count agar were used for Heterotrophic plate Count and standard microbial procedures were followed. physicochemical qualities of water samples analyzed by portable digital photometer instruments following instrument instructions. Among a total of 220 water samples 46(43.3%) of hot spring samples; 22(38.6%) of hospital water samples; 8(30.7%) of Addis Ababa water distribution system and 19(61.3%) of natural water samples were positive to Legionella spp. The Legionella colonies of hot springs range from Log10 2.60 ±0.69 to 3.22±0.78; natural water bodies 1.66±0.8 to 3.29±0.3; Addis Ababa water distribution samples 1 to 1.41±0.8 and Hospital water samples 1.22±0.46 to 2.8±1.41 Log10 cfu/l. Meanwhile 23(21.7%), 12(21.05%) and 3(11.5%) of hot springs, hospital water samples and Addis Ababa water distribution system had HPC >300cfu/ml respectively, while 23(74.2%) natural water bodies had HPC>2500cfu/ml. Temperature (OC) range were 35.3±1.4 to 48.3±5.5 in hot springs IV
while from 18.6±1.1-25.2±0.4 in natural water bodies; pH varies 6.5-7.5 in hot springs; 6.9-7.4 in hospital water; 6.6 to 8.5 in natural water bodies; mean Fluoride and Iron levels range 2.6-30.4 and 6.1-23.1mg/l in hot springs; 0.2-0.4 and 0.6-0.6mg/l in hospital water samples; 0.2-7.1 and 0.4-8.4mg/l in natural water bodies but range from 0.21-30.4 and 0.34-23.1mg/l respectively. The mean free residual chlorine from the sampled hospital and Addis Ababa water distribution system was below 0.2mg/l. The minimum and maximum concentration of elements all samples ranged, Potassium 1.9-44.8mg/L; Phosphate 4.95-48.3mg/L; Sulfate 2.2-59.7mg/L; Total alkalinity 61.7-4752.0mg/L; Total Dissolved Solids 88.7-2569mg/L; Electrical Conductivity 130-1813.7(μS/cm). Significant level of correlation was observed between microbial parameters of Legionella and heterotrophic plate count. HPC correlated with Legionella at P<0.05(r=-0.494) HS2; (r=0.464) Yekatit 12 hospital but at P<0.01 (r=-0.528) HS1; (r=-0.722) HS3; (r=0.859) AAWDS; (r=-0.461) Zewditu hospital (ZH). Significant positive correlations observed between Legionella and Temperature r= 0.424(HS2), with TDS r=0.463(HS1), with phosphate r=0.497(HS4); whereas negative correlations observed with fluoride r=-0.497(HS4), Temperature r =-0.416(Y12H), with free residual chlorine between r=-0.468 to -0.751 from all of sampled hospitals and Addis Ababa water distribution system. This study indicates the presence of Legionella within diverse physicochemical water sources and can enlarge our knowledge towards Legionella and associated physical-chemical and microbial parameters from Ethiopian water bodies. Education and awareness have to be given for potable water suppliers, property or building owners about risks associated with Legionella and other infections. Potable water systems should have to maintain adequate treatment residual chlorine and practice good pipe maintenance as important water safety plans. Water systems have to be closely monitored the microbial level and mechanisms to control and prevent possible outbreak are needed by owners, stakeholders, and regulatory bodies. Legionella species identification by molecular methods needs to be determined by further study.
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Keywords
Legionella Spp, Hpc, Physicochemical and Microbiological Quality, Water Distribution System, Hot Springs, Hospitals, Lakes, River