Presence and prevalence of Legionella spp in collected rainwater. Biosafety, Air and Water Microbiology Group

Transcription

1 Presence and prevalence of Legionella spp in collected rainwater Ginny Moore Biosafety, Air and Water Microbiology Group PHE Porton Laura Steege Placement student University of Surrey 4 th ESGLI Conference, Amsterdam, September 22 nd 23 rd 2016

2 Responding to a changing climate Government UK National Adaptation Programme help people prepare for the impacts of climate change Industry Water Industry Act (1991) statutory requirement to promote the efficient use of water Domestic user 95% of water does not need to be of potable quality demand can be met through alternative sources 2 Presence and prevalence of Legionella in collected rainwater

3 Collection and use of rainwater Benefits has the potential to reduce water consumption by 6% can reduce the load on storm water drainage systems Uses non-potable indoor activities (e.g. laundry; flushing of toilets) outdoor activities (e.g. watering of gardens) Microbiological risks public perception of risk is low microbiological quality of roof harvested water can be poor 3 Presence and prevalence of Legionella in collected rainwater

4 Rainwater and Legionella Older adults (> 60 years) most likely to spend leisure time gardening most likely to collect and use rainwater Age is a risk factor for Legionnaires disease individuals over the age of 50 have highest risk of infection : case fatality rate for those 70 years or older = 18.6% Potential public health risk presence of Legionella spp in collected rainwater aerosolisation through common gardening activities 4 Presence and prevalence of Legionella in collected rainwater

5 Aims of investigation 1. Investigate the presence and prevalence of Legionella spp in collected rainwater volunteers were asked to supply a sample of water from rainwater storage butts volunteers were also issued with a questionnaire water samples were subjected to microbiological and chemical analysis (ph; nitrate concentration; dissolved oxygen) the presence of Legionella spp was determined via qpcr 5 Presence and prevalence of Legionella in collected rainwater

6 Aims of investigation 2. Investigate factors that influence the level of Legionella spp in collected rainwater two new rainwater storage butts were installed at PHE Porton monthly water samples taken from the surface and via the tap (Oct 2015 Aug 2016) samples subjected to microbiological and chemical analysis the ambient temperature and RH and the temperature of the water (surface and base) was logged continuously number of rain days was also recorded 6 Presence and prevalence of Legionella in collected rainwater

7 Aims of investigation 3. Investigate the dissemination of Legionella spp during common gardening activities watering can filled with water taken from rainwater storage butt hosepipe attached to a submersible water butt pump 7 Presence and prevalence of Legionella in collected rainwater

8 Aims of investigation 3. Investigate the dissemination of Legionella spp during common gardening activities watering can filled with water taken from rainwater storage butt hosepipe attached to a submersible water butt pump cyclone air sampler positioned 1 metre from gardener collecting fluid sampled for Legionella spp and cultured to obtain a heterotrophic plate count 8 Presence and prevalence of Legionella in collected rainwater

9 Presence and prevalence of Legionella spp in collected rainwater 63 volunteers provided water samples taken from 113 different water butts Legionella spp detected (via qpcr) in 107 (95%) of samples (mean: 4.7 x 10 4 gu L -1 ) L. pneumophila SG 1 detected in 2 (1.9%) of 107 Legionella positive samples (mean: 8.9 x 10 3 gu L -1 ) L. longbeachae not detected 9 Presence and prevalence of Legionella in collected rainwater

10 Presence and prevalence of Legionella spp in collected rainwater mean heterotrophic plate count: 2.0 x 10 8 cfu L -1 (range: 3.0 x x 10 9 cfu L -1 ) water chemistry ph: dissolved oxygen: ppm nitrates: ppm No correlation between Legionella counts, HPC, water chemistry or any factor included in the questionnaire (e.g. positioning of the water butt; frequency of use) 10 Presence and prevalence of Legionella in collected rainwater

11 Presence and prevalence of Legionella spp in collected rainwater 10% sub-sample (n=11) water samples taken from surface and via tap Legionella counts (gu L -1 ) were significantly higher in water taken via the tap (i.e. from the base) than in that taken from the surface water samples taken in November and August Legionella counts were significantly higher in November prevalence of L. pneumophila higher in August (0 vs 18%) 11 Presence and prevalence of Legionella in collected rainwater

12 Factors influencing the level of Legionella spp in collected rainwater Temperature of rainwater significantly lower when stored in the shade Legionella counts significantly higher in the water butt positioned in the shade 12 Presence and prevalence of Legionella in collected rainwater

13 Factors influencing the level of Legionella spp in collected rainwater Temperature of rainwater significantly lower at base of storage butt Legionella counts do not significantly differ between sample points 13 Presence and prevalence of Legionella in collected rainwater

14 Factors influencing the level of Legionella spp in collected rainwater Small but significant legionella gradient in established domestic rainwater storage butts 14 Presence and prevalence of Legionella in collected rainwater

15 Factors influencing the level of Legionella spp in collected rainwater Independent variable t-stat p-value mean ambient RH (month prior to sampling) e-07 mean ambient temperature (week prior to sampling) e-05 number of rain days (week prior to sampling) level of dissolved oxygen (ppm) adjusted R Presence and prevalence of Legionella in collected rainwater

16 Perceived risk of using stored rainwater 16 Presence and prevalence of Legionella in collected rainwater

17 Perceived risk of using stored rainwater 17 Presence and prevalence of Legionella in collected rainwater

18 Perceived risk of using stored rainwater 18 Presence and prevalence of Legionella in collected rainwater

19 Dissemination of bacteria during common gardening activities Watering can use: No significant increase in the number of bacteria recovered from the air 19 Presence and prevalence of Legionella in collected rainwater

20 Dissemination of bacteria during common gardening activities Watering can use: No significant increase in the number of bacteria recovered from the air Hose pipe use: Significant increase in the number of bacteria recovered from the air. The fine spray (mist) setting results in more bacteria reaching the users head 20 Presence and prevalence of Legionella in collected rainwater

21 Dissemination of Legionella spp during hose pipe use 21 Presence and prevalence of Legionella in collected rainwater

22 Dissemination of Legionella spp during hose pipe use 22 Presence and prevalence of Legionella in collected rainwater

23 Conclusions Presence and prevalence of Legionella spp in stored rainwater Legionella spp are common contaminants of stored rainwater failure to culture prevented identification L. pneumophila was detected (2.7% in-use rainwater storage butts) Factors influencing the level of Legionella spp in stored rainwater positive effect: ambient temperature and humidity negative effect: persistent rainfall 23 Presence and prevalence of Legionella in collected rainwater

24 Conclusions Dissemination of bacteria during common gardening activities risk associated with common gardening activities is low any associated risk can be minimised by standing upwind A public health risk? L. pneumophila may be present older people should not be discouraged from gardening other organisms likely to be present (e.g. faecal contaminants) hand hygiene should be encouraged 24 Presence and prevalence of Legionella in collected rainwater

25 Thanks to: PHE Porton Engineering and Maintenance Department Sam Collins David Stevenson Idexx Water Nigel Otter All those who sampled their butts