Issues for Pest Management

Issues for Pest Management

Dr Stephen BattersbyPresident, CIEH

Summary

• Health risks from rodents

• EU & the Biocidal Products Directive (BPD)

• Resistance & second generation anti-coagulants

• Other pests, e.g. bedbugs

• Public sector cuts and pest control services

• Climate change and vector control

Rodents and public health

• It has been suggested that mice are merely a nuisance pest – that is not so

• WHO Publication “Public Health Significance of Urban Pests “ - mice “should be treated as a potential threat to public health”

• Rat infestations in urban areas also a symptom of a degraded environment

Summary of diseases associated with rodents (primarily Rattus spp and Mus spp)

Human disease Vector, pathogen or both

Ectoparasites

Bubonic plague Asiatic rat flea – Y. pestis

Louse Borne Relapsing Fever (LBRF)

Body louse – B. recurrentis

Tick-borne relapsing fever Ticks (Ornithodoros hermsi) – Borrelia spp.

Lyme disease Ticks (Ixodes spp.) – B. burgdorferi

Rickettsial pox a Rodent mite (Liponyssoides sanguineus) – Rickettsia akari

Murine typhusa Asiatic rat flea – R. typhiBody louse– R. typhi

a Indicates zoonoses of both house mice and Rattus spp.;

Summary of diseases associated with rodents (primarily Rattus spp and Mus spp), 2

Human disease Vector, pathogen or both EndoparasitesCapillariasis Capillaria spp.Toxocariasis Toxocara spp.Rat tapeworm infection Hymenolepis nanaAngiostrongylosis Strongyloidea sppDiarrhoeal disease Trichuris spp.Diarrhoeal disease Hymenolepis spp.Diarrhoeal disease Taenia spp.Schistosomiasis Schistosoma spp.Trichinellosis Trichinella spp.Cryptosporidiosis a C. parvumToxoplasmosis a T. gondiiBabesiosis Babesia spp.Sarcosporidiosis Sarcocystis spp.Coccidiosis Coccidia (Eimeria spp.)Amoebic dysentery Entamoeba spp.(e.g E. Histolytica and E.

muris)

Summary of diseases associated with rodents (primarily Rattus spp and Mus spp), 3

Human disease Vector, pathogen or bothBacteria

Leptospirosis a(Weils’ disease) Leptospira spp.Listeriosis Listeria spp.Yersiniosis Y. enterocoliticaPasteurellosis Pasteurella spp.Rat-bite fever (and Haverhill fever) a Streptobacillus moniliformis &

Spirillum minusMelioidosis Pseudomonas spp.Q fever C. burnetii Salmonellosis a Salmonella spp.Diarrhoeal disease Vibrio spp.Tularemia F. tularensisE. coli 0157/VTEC E.coli 0157

Summary of diseases associated with rodents (primarily Rattus spp and Mus spp), 4

Human disease Vector, pathogen or both

VirusHantaan fever (Haemorrhagic fever with renal syndrome (HFRS))

Hantavirus (Bunyaviridae)

Haemorrhagic fever with pulmonary syndrome (HFPS)

Sin nombre hantavirus

Lassa fever Arenaviridae virus

Lymphocytic choriomeningitis b Lymphocytic choriomeningitis virus

b Indicates zoonosis only of house mice Mus musculis

Examples of pathogens that may be transmitted by rodents & risk

Disease Agent Carrier or

Reservoir

Pop at

risk

Chance

Severity – human health

Q FeverBacteria,Gammaproteobacteria

Reservoir 3 2 3

Toxoplasmosis

Parasite, Sporozoea

Reservoir3 2 2

E. coli 0157/VTEC

Bacteria,Gammaproteobacteria

Carrier 2 1 3

Based on: Meerburg BG, Singleton GR, & Kijlstra A, 2009, Rodent-borne diseases and their risks for public health, Critical Reviews in Microbiology, 2009; 35(3): 221–270

NB. This is a global assessment.

• In Baltimore USA, Hantavirus antibody prevalence rates of 50%+ have been found

(See: Easterbrook JD, Shields, T Klein SL & Glass GE, Vector Borne Zoonotic Dis. 2005 Fall;5(3):296-9: Yanagihara R, Rev Infect Dis 1990 May Jun;12(3):449-57R: and Childs JE, Korch GW, Glass GE, LeDuc JW, Shah KV Am J Epidemiol. 1987 Jul;126(1):55-68. for example)

• Humans are the only known disease end point of the infection.

Hantavirus

Buenos Aires Study

• 10 sites sampled & 151 R.norvegicus trapped

• Hantavirus seroprevalence was 11.9% varying between 0% and 26.1% depending on site

• Hantavirus infections geographically widespread in city

• They have been enzootic for at least 20 years

(Cueto GR, Cavio R, Bellomo C, Padula PJ, Suarez OV, 2008, Trop Med & Int Hlth, 13, 1, 46-51.)

Rodents and public health

• Strategies to address the risks to public health should be more than “individual treatments”

• There is a need for a properly trained and equipped workforce within public authorities to devise and implement coherent pest management strategies

• States should also establish more effective surveillance mechanisms

EU & the Biocidal Products Directive (BPD) etc

• Process of assessment under BPD

• Anti-coagulant rodenticides part of “Product Type 14” comprise 9 of 13 (70%) active substances approved under BPD and represent 90% of products used in practice

• Cost and time to secure Annex 1 listing means 80% of active substances in EU in 2002 withdrawn by manufacturers

• Moves on further restrictions and use of tamper resistant baitboxes required

Resistance & second generation anti-coagulants

• Research to assess the extent of resistance underway in England and Wales

• Without changes in approach it will be impossible to control rats with anti-coagulants in some parts of the UK

• Restrictions on product approvals hamper control – e.g. Brodifacoum approved for indoor use only

• Resistance also has an impact on non-target species and wildlife

Other pests - bedbugs

• Bedbug (Cimex lectularius) numbers are increasing sharply

• Nuisance and economic problem (especially in hotels)

• Feeding at night on sleeping human hosts -itching caused by the bites; possibility of secondary infection are common

• Ineffective treatments common

• See NPAP Pest control procedures manual – Bedbugs (see http://www.cieh.org/npap)

Cuts and pest control services

• NPAP Survey - for all pests, reduction in the overall number of LA.s providing in-house treatments only 89.9%. Provide any service.

• Introductions of even token charges for pest control services decrease demand

• In 2002 174 respondent LA.s provided free treatments for rats in domestic premises in 2009 it was 112 (- 36%) – figures for mice 121 in 2002 to 71 in 2009(- 41%)

Cuts and pest control services 2

• More LA.s taking enforcement action - less time spent in exploring other environmental health options?

• Not necessarily the most cost effective approach

• Loss of LA expertise in pest management & reduction in the services which protect some of the most vulnerable groups and those who are least likely to be able to afford to pay for services

• Increase in ineffective DIY treatments?

Climate change

• Yersinia pestis prevalence in gerbils in Central Asia increases with warmer springs and wetter summers

• Possibility of increased tick-borne encephalitis (TBE) in Europe

• Mosquito problems spatially and temporally more extensive in warmer climates

• Biting insects – non-malarial mosquitoes; increased risk of West Nile Virus? Culex pipiens molestus causes serious biting nuisance.

Climate change

• Risk from invasive species such as Aedes albopictus, has been recorded in nine European countries and caused the Chikungunya outbreak in Italy

• Malarial mosquito vectors - records of clusters of mosquito borne disease cases near airports - “airport malaria” , however land-use changes may be important factor and risk of malaria seems remote in the British Isles

Climate change and human behaviour

• Alien invasive species are a large threat to biodiversity (Mack et al. 2000; IUCN 2008), and the economic damage they cause exceeds 5% of the global gross product (Pimentel 2002).

• Synanthropic rats reflect human activity and are one of the most invasive species – will global travel etc increase infections within rodent population?

• Human behaviour may also change with climate, bringing closer contact between rats and humans

Climate change and human behaviour.2

• Increased water-use and flooding with sewers running at full capacity – causing rats to abandon sewerage system

• Lack of water compromises personal hygiene

• Increased outdoor living

• More food waste not correctly stored and disposed of (and spoilage)

• Doors etc left open compromising “pest proofing” of buildings (dwellings)

Conclusion

• A quick run through some issues

• Pest management is often the forgotten part of environmental health

• Pests can have both direct effects on health including mental health and the quality of life.

• Governments need to take better account of pests and public health in policy development

THANK YOU