EHJ May 2002, pages 152-153 Are rat complaints increasing due to a lack of co-ordination on rodent control policies? Tracey Khanna reports

The National Rodent Survey Report 2001, published by the National Pest Technician's Association (NPTA) in December 2001, was the organisation's second annual attempt at assessing the nature and true extent of the UK's rodent problem.¹ The results point to a sharp increase in rat complaints received by local authorities during the period 1999-2000, and the statistics were pounced on by the media and local radio stations - keen to capitalise on the public's fears and sensationalise the problem.

In July/August last year, the NPTA sent a survey questionnaire to every district and borough council and unitary authority within England, Northern Ireland, Scotland and Wales. However, according to J Barrie Sheard, promotions officer to the NPTA and member of the CIEH, only half responded. This problem appears to have been compounded in Northern Ireland, where the particularly poor response rate has led the NPTA to conclude that "these particular statistics are not a true reflection of the actual situation".

Nonetheless, the overall results of the survey point to a rodent problem that is on the up. While average figures for brown rats (Rattus norvegicus), varied wildly between individual local authorities, the average total UK figures suggest a 6 per cent increase in brown rats on the previous period. Adding this 6 per cent increase to the 18 per cent increase reported in the previous year's report, the NPTA claims that there has been a reportable total increase of 24 per cent for the years 1998, 1999 and 2000.

With regard to house mice and what the NPTA terms "summer rat" (the total number of brown rat infestations reported and dealt with during the summer period of April to September), the report shows a total average decrease of 5 per cent in 2000 for house mice and a total average decrease of 1 per cent for the "summer rat". Adding these figures to those reported for the period 1998-1999, indicates that there has been an overall average increase of 30 percent in reports of "summer rat" and an overall decrease of 7 per cent for house mice (see table 1).

Following the release of its first report, the NPTA came under fire from a number of academic institutions and organisations who criticised the methodology used. Despite this criticism, the NPTA says that it had little help in the production of this second report from those same bodies. Apart from one major change, deleting all questions concerned with the black rat (Rattus rattus), and one minor change, asking for total number of initial visits "where a treatment was carried out" rather than just number of initial visits, the NPTA used the same methodology for its second report.

Mr Sheard presses the point that in keeping to the same statistical methods year on year, the annual results are directly comparable. According to Mr Sheard, "since the report was published, we have had two local authorities contact us to say that they were sorry they had not supported us". He goes on to say that some local authorities have indicated that they will computerise the survey in future years, if the organisation keeps to the same methodology.

However, questions concerning the black rat were left off the survey this year because, according to the NPTA, "not one local authority in the previous survey (1998-1999) had any statistics identifying the black rat". Worryingly, the NPTA questions whether local authorities are able to distinguish between the brown and black rat anymore! More likely, says David Aldbury, the group secretary of the CIEH's National Pest Advisory Panel (NPAP), is that local authorities are not reporting infestations of Rattus rattus due to this species being of lesser "significance" in the UK than Rattus norvegicus.

One of the main criticisms levelled at the NPTA's survey is that it relies on complaints made to local authorities as a measure of infestation. Thus, one complaint could represent the sighting of a single rat or multiple rats, and equally, several complaints in the same area could relate to the same rat, or rats. However, according to John Swift, writing in International Pest Control last year, while the number of rat complaints cannot indicate a specific level of infestation, over time it is likely that complaint levels are indicative of infestation trends.²

Mr Swift, senior environmental health officer with Leeds City Council, has identified the possibility of a "10-year cycle" with regard to complaints made to the council. From the data held by Leeds CC, he has concluded that complaint peaks have been occurring regularly at the end of decades, with intervening trough years.2 If this 10-year cycle is proved to exist, through further collection of accurate population data, Mr Swift believes that there are a number of implications as far as control measures are concerned. "Control should not be concerned in dealing with the obvious rats," he says, "but greater efforts must be made to seek out the sources of infestation".

As one pest control professional has commented, "in my area all rat complaints can be tracked back to some problem with the sewer system, except on the town outskirts where there are open ditches etc, which is entirely due to the age and condition of the sewers and lack of maintenance".

Many EHOs and private pest control contractors find themselves in the position whereby they eliminate rats that are present at the time of their visit, but then have to return time and again to deal with the same problem. It seems that a lack of co-operation and co-ordination between water companies, private contractors and local authority departments, and little funding, is making effective control impossible.

In addition to the lack of funding for sewer control from water companies and lack of investment in sewer repairs, there is also still little co-ordination between different local authorities. Each authority tends to deal with complaints on a reactive basis, and little heed is taken of the implications of individual pest control treatments across local authority boundaries.³

In fact, the NPTA is disturbed to note the increasing trend for local authorities to charge for their services - a major issue with regard to control policies. According to the survey report, "the increasing use of charging policies by a proportion of local authorities on what has always been a vital preventative health measure" is "immediately producing a reduction in complaints and request for treatments". As one local authority reports: "We have included out of interest the figures from April to September 2001, because from 1 April we introduced a £25 charge for a complete treatment. We find a 'summer rat' increase from 1999 to 2000 of 16 per cent turning into a 71 per cent decrease from 2000 to 2001. Tells a story doesn't it!"

At the time of writing, the NPAP and the CIEH were co-organising an open members forum (OMF), due to take place in York at the end of April. The main aims and objectives of the OMF are to raise the profile of pest management in the UK, and to establish lines of communication between local authorities, academics, industry and central government. Priority issues that the panel intends to focus on, through its working groups, are the control of rats in sewers, a national baiting strategy, the relationship between surface and sewer infestations and disease transmission.

In the meantime, it seems unlikely that we will see a cessation in the media of its sensationalist coverage of the rats issue as the presence of rats is seen by the public as a direct indication of a dirty and unhealthy environment. And that perception, not the real problems behind rodent control policy, is the political hot potato.

Reference

1. National Rodent Survey Report (2001), National Pest Technicians Association, December 2001, Nottingham.
2. Swift, J (2001) "Rat population dynamics - is there a 10-year cycle?" International Pest Control, July/August 2001, Vol 43 No 4, page 156.
3. Khanna, T (2001) "Public enemy No.1", Environmental Health Journal, Vol 109/04 April 2001, page 106.

For further details of the outcomes of the open members forum on pest control, please contact Andrew Griffiths by e-mail: a.griffiths@cieh.org