Appendix 2 Information on Sewer Baiting and the Control of Rats ...

<strong>Appendix</strong> 2<strong>Information</strong> on Sewer Baiting and the Control of RatsGeneral information on ratsUrban sewers are the perfect man made habitat for rats. They provide a steady influxof food and there is a stable climate so that breeding continues all year round. Sewerscan therefore provide a reservoir of rats which restock surface areas where controlsare in place. Hence, sewer systems are important harborages for urban rat coloniesand should be considered in conjunction with surface control efforts (Twigg 1975).In urban areas of the UK at least a quarter of surface infestations in over a half of thelocal authority districts are due to defects in the sewer system. In some localauthorities over half the surface infestations are attributable to defects below ground(Battersby, 2002).Channon et al (2000), examined data from sewer baiting records over a 13 year periodin one London borough, baiting at a rate of approximately 3000 manholes per year.Plotting the proportion of bait takes against the year showed a gradual decline in therat population. This leveled off at about 1% to 2%, indicating that, even withcontinuous baiting, complete eradication may not be possible and that sewers willalways remain a potential source of infestation.Furthermore, with reports of deterioration in the integrity of the sewerageinfrastructure, coupled with less sewer baiting, (Battersby 1998, 1999), rats may haveincreased opportunities for contact with humans in an urban environment(Bradshaw,1999). This will be particularly relevant in those areas of Belfast currentlyserved by an older sewerage network.A female rat can produce eight young every 3-4 weeks under favorable conditions. Socontrol rates in excess of 80% are essential if treated populations are not to reestablishthemselves in little more than a month.The World Health Organisation, WHO, (1998) has said that rat control in sewersand drains is an essential part of any rat control programme on the surface.Problems associated with rodents:Rats pose a range of health hazards and they can be affected with a large range ofparasites many of which are transmissible to man. They can damage structures,contaminate products, and pose fire and flood risks due to their behavior. Pestinfestations also make urban areas undesirable and can inhibit inward investment.Rats are often found in substandard dwellings where building density is very high.According to one study, the typical rat-bite victim is an impoverished child lessthan 5 years old, living in substandard housing. Also, damage to infrastructure byrats costs the British economy between £62 - £209 million per year. (Urban pests andtheir public health significance: A CIEH Summary2008.)

National Rodent Survey(These surveys involve responses from local authorities in the UK)The National Rodent Survey 2002 suggested that there was a 29% increase in brownrats between 1998 and 2002. One of the possible reasons put forward as to why therodent populations were growing was due to a reduction in funding by the privatizedwater authorities. This has meant that routine sewer surveys and treatments have beencurtailed.The National Rodent Survey 2007/2008 found that brown rats continue to be aproblem. The number of brown rat treatments were found to be over 378,000, up by44% on the previous year, with like-for-like treatment levels up more than 15%. Thesurge in rodent problems across the UK was traced back to a failure to get on top ofpopulations the previous year. Exceptionally mild conditions through the 2006/2007winter meant rats were much less evident than usual in and around buildings.Exacerbated by the decrease in rodent control in many areas this led to a markeddecline in both complaints and treatments. The population of rats increased greatlyand this led to a surge of complaints and treatments with the colder autumn weather in2007.Under half of the recorded treatments took place in the summer and just over half inthe winter. Mainly as a result of the very much higher levels of winter treatment, thisrepresents a clear change from the previous year when over 60% of rat treatmentswere in the summerThe National Rodent Survey 2009/2010 states that local authority economies arealready threatening public health. Their benchmark annual report shows the largestyearly fall in recorded local authority rat treatments since the survey was instituted in1999. At the same time, it reveals that much of this decline results from changes incharging practice rather than any decline in infestation levels. On a like-for-like basisthe latest NPTA survey shows national brown rat treatments were down by 19%, withthe notable exception of Northern Ireland.Rat activity/sewer baiting in BelfastSewer baiting treatments in Belfast increased from 16542 in 2008/09 to 17557 in2009/10, (an increase of 6%), and the rat complaints dropped by almost 4%.Over the last 30 years the levels of rat complaints has increased, with most problemsarising in areas of deprivation.Other research/evidenceIt is the experience of local authorities such as Oldham MBC and Kinston upon HullCC, which have undertaken careful monitoring of rat activity, that above groundinfestations are reduced with proactive baiting, in the latter case using the pulsedbaiting method (CIHE Sewer baiting and the control of rats 2003).

Thames Water staff and a group of EHOs have drawn up the London Sewer BaitingProtocol. London divides into three sectors and each sector identifies rodent hotspotsfor action. Evidence showed hotspots were coming under control and one such areawas Walthamstow High Street, well known for its street market and its prevalence ofrats. A vagrant died in the town square and, when his body was found several weekslater, it had partly been eaten by rats. Now the high street is almost rat free. (CIEHWar on Rats, 1 st July 2011)Paul Charson, Public Protection and licensing manager with West Lancashire BC, hasoutlined their pro-active baiting programme. They monitor rat activity detectedduring their baiting programme and adjust their future programmes accordingly,taking into account their findings. They report approximately a 12% decrease inrodent activity in the sewers since 2006.CIEH –Position statement on sewer baiting- Nov 2003CIEH believes that local authorities should include within their sewer baitingstrategies an element of proactive sewer baiting for those parts of local authority areaswhere this approach is most appropriate.They encourage the development of joint strategies between local authorities andwater companies for sewer baiting and the control of rodent populations.CIEH is concerned that rat control in sewers generally is inadequate and under fundedand this failure is leading to an increased population above ground which localauthorities will have to deal with out of their limited budgets. Token one-offpoisoning in a sewer system will kill some rats. However, even when a population hasbeen reduced to a very small percentage of that originally in place, recovery to theoriginal number can still occur with six months.CIEH believes that public pest management is a job more suited to local authoritiesthan to private companies because pest management goes further than simple pestcontrol. Local knowledge and records within a local authority can help identify thoseareas of a city where the sewers continue or are likely to contain larger populations ofrats. Proactive baiting can therefore still allow for the targeting of resources, as wellas helping to prevent movement of the rats through the sewer catchment area or out ofsewers..

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