Dust mites Studies examining thresholds of exposure relevant to disease
1.5.2. Factors associated with exposure to dust mite allergens
Dust mites are found in the bedding, pillows, mattresses, carpets and upholstered furni- ture of homes, where they feed on scales from human skin Tovey et al., 1981. They absorb water from the air, and therefore require a relative humidity above 50 to survive Arlian, 1992. T his restricts the environments inhabitable by mites and is a major controlling factor in the geographical distribution of dust mites. Reducing indoor air humidity has recently been used with some success as a mite eradication strategy Arlian, Neal Vyszenski-Moher, 1999; Arlian et al., 2001. In major cities of the north-eastern United States, multifamily buildings are often overheated during the winter, which leads to low humidity air indoors and precludes the proliferation of dust mites Chew et al., 1999a. Mite genera vary geographically, with Dermataphagoidesbeing more common in temperate climates and Blomia being found only in tropical climates Arlian, Morgan Neal, 2002.1.6. Proposed thresholds of exposure to allergens associated with allergic asthma
1.6.1. Studies examining thresholds of exposure relevant to disease
Prior exposure to an allergen is necessary for an immediate hypersensitivity immune response; however, the quantity of allergen necessary for sensitization appears to depend on the allergen in question, concurrent exposure to other substances that stimulate the immune system and the genetic predisposition of the individual being exposed. In exa- mining thresholds of exposure to pests or more specifically allergens from those pests that lead to allergic disease, it is first necessary to consider allergic sensitization and symp- toms of allergic diseases as separate outcomes. The level of allergens in homes necessary for allergic sensitization – that is, development IgE antibodies – is probably less than is necessary for precipitating asthma symptoms Platts-Mills et al., 1992. For example, for dust mite allergens, the proposed threshold of exposure for sensitization is fivefold lower than that for asthma symptoms Sporik et al., 1990. The strongest scientific evidence for a threshold level of exposure to an allergen exists for dust mite allergens; however, the levels proposed by Sporik and colleagues 1990 have been debated by subsequent studies Warner et al., 1996. Due to the design of studies conducted to date, mostly cross-sectional and lacking controls non-asthmatics, the thres- holds for developing sensitization to cockroach and mouse allergens have not been well established. Recent studies suggest that the differences observed between studies that eva- luated the risk of exposure to mite allergens may likely be due to the influence of concur- rent exposures that alter the immunological response and genetic factors that affect an individual’s susceptibility to produce IgE antibodies in response to an allergen see sub- section 1.1.1.1 Kleeberger Peeden, 2005.1.6.1.1. Dust mites
Based on findings from a prospective birth cohort in 1990, Sporik and colleagues propo- sed a threshold level of the dust mite allergen Der p 1 from the house dust mite Dermatophagoides pteronyssinus sufficient for sensitization 2 µgg and a threshold for an increased risk of asthma 10 µgg Sporik et al., 1990. However, subsequent studies have proposed that exposure to much lower concentrations is sufficient for sensitization in a sizeable fraction of the population Munir et al., 1995; Warner et al., 1996. Exposure to dust mite allergens in the home does appear to have a dose–response relationship, with those individuals exposed to more allergen being more likely to become sensitized to mite allergens, especially among those with atopic mothers Platts-Mills et al., 2001; Cole Johnson et al., 2004; Brussee et al., 2005; Kerkhof et al., 2005. In communities where dust mite allergen in most homes is greater than 10 µgg, the population response appears to plateau, leading to the majority of allergic individuals being sensitized to mite, likely indicating saturation Marks, 1998. As discussed in subsection 1.6.1, the response to exposure to dust mite allergens, as well as to other allergens, is likely influenced by environmental exposures and the genetic pre- Public Health Significance of Urban Pests Allergic asthma 25 24 disposition of the individual, and this can explain differences in thresholds reported from different studies. A recent study in a birth cohort in Manchester, England, found that increasing exposure to dust mite allergens was associated with an increased risk of sen- sitization, but that effect was dampened if the children were also exposed to higher levels of endotoxin. However, the modifying effect of endotoxin was only observed in children with a specific genetic polymorphism in a gene for an endotoxin binding receptor Simpson et al., 2006. From this example, it is clear that defining allergen exposure thres- holds is complicated by other environmental exposures and by individual genetic sus- ceptibilities.1.6.1.2. Cockroaches
Parts
» TAP.COM - PUBLIC HEALTH SIGNIFICANCE OF URBAN PESTS - WHO/EUROPE - WORLD ...
» Risk of developing allergic sensitization
» Risk factors for developing asthma
» Public health impact of urban asthma
» Dust sampling Airborne sampling Comparison of various methods of allergen exposure assessment
» Cockroach sensitization and asthma
» Size characteristics of airborne mouse and rat allergens Residential exposures
» Dust mites Studies examining thresholds of exposure relevant to disease
» Cockroaches Rodents Studies examining thresholds of exposure relevant to disease
» Comprehensive avoidance of dust mite allergens Multifaceted primary prevention studies
» Limited avoidance of dust mite allergens
» Targeting housing conditions of high-risk groups
» Smokybrown cockroach American cockroach Oriental cockroach
» Brownbanded cockroach Allergy and asthma overview
» Food contamination and disease transmission
» Cost of control and management
» Impact of poverty Cockroaches
» Public costs 1. Cost of health-related conditions
» IPM of cockroaches Cockroaches
» Baits Cockroach control: pesticide applications
» Alternative strategies Cockroach control: sanitation practices
» Biological control Conclusions Cockroaches
» Origins and natural history Habitats within the home
» Food Limiting factors Distribution in Europe and N orth America
» CEH Distribution in Europe and N orth America
» The building envelope Impact of building construction
» The ventilation and heating system
» Furniture and furnishings Overall effect of the housing environment on health or illness
» Sampling methods Dust mite and allergen inspection and detection methods
» Mechanical solutions Modifying environmental conditions
» Washing Dusting Dry cleaning Vacuuming
» Home disinfectants Electric blankets Bed heaters Freezing
» Sunlight Steam cleaning Cleaning
» Autoclaving Steam cleaning Temperature control
» Barrier fabrics Temperature control
» Habitat modification Carpets Physical control methods
» Soft furnishings Air filters
» Anti-allergy sprays Antimicrobial treatments Dehumidifiers
» Pesticides Building construction Methods of house dust mite control
» Control methods Medical practitioners Other
» Background Biology and bionomics
» Other species of Cimicidae that can affect people
» Evidence of resurgence in N orth America
» Future prospects Resurgence of bedbug populations in Europe and North America
» Importance as pests Economic impact Bites and health effects
» Conducive environmental conditions An integrated approach to bedbug management
» Physical removal Exclusion Physical removal and exclusion
» Inspection Detection Inspection, detection and education
» Heat Cold Controlled atmospheres
» Use of pest management products
» Benchmarks for success in bedbug management Conclusions
» Introduction Flea biology Fleas
» Health risk and exposure assessment
» Cost for control and management
» Cost of health-related conditions
» Flea exclusion and physical removal Pesticide applications for flea control
» Foggers General surface treatments IGRs
» On-animal products Conducive environmental conditions
» Pharaoh ant biology Overview of biology and distribution in Europe and North America
» Health hazards 1. Pharaoh ant infestations: pathogen transmission and contamination
» Pharaoh ant distribution and population monitoring
» Fire ant population assessment and monitoring methods
» Fire ant geographic range and potential expansion Fire ants: stinging incidents
» Fire ants: cost of eradication
» Physical exclusion Residual contact insecticides
» Insecticidal baits Fire ants: cost of health-related issues, control and management
» Efficacy of management practices
» Implementation of fire ant control programmes
» Confirmation. Determine where control is needed.
» Fire ants Emerging problems and policy options
» Introduction Biology and bionomics of filth flies in Europe and North America
» N uisance Health hazards 1. Diseases
» Myiasis Health hazards 1. Diseases
» Pesticide applications for fly control Granular baits
» Fly exclusion practices Crack-and-crevice treatments Biological control
» Ultraviolet light traps Sticky traps Jar or bag traps Window traps
» Attractants Perimeter treatments Fly management
» Togaviridae: genus Alphavirus Viruses
» Orthomyxoviridae: genus Orthomyxovirus Bacteria
» Coxiellaceae Anaplasmataceae Spirochaetaceae Bacteria
» Regular nonsporing Gram-positive rods Mycobacteriaceae
» Microsporidia Babesiidae Eimeriidae Protozoa
» Zoonoses and sapronoses of wild birds in the urban ecosystem
» Monitoring and surveillance Management implications 1. Benchmarks
» Techniques for dispersing birds in cities
» Control of wild and feral birds in urban areas
» Economic impact of wild urban birds on human health and of controlling birds
» Introduction Human body lice
» Biological factors Implications for public health
» Louse infestation in Europe and North America
» Physical removal Pesticides Louse management 1. Inspection and detection
» Socioeconomic influences Conducive environmental conditions
» Benchmarks for lice management
» Introduction Ticks of Europe and North America
» LB in Europe and N orth America
» Geographical distribution Lyme borreliosis
» Public health impact of TBE in Europe
» Geographical distribution Geographical distribution Epizootiology and epidemiology
» HME HGA Crimean-Congo haemorrhagic fever
» Boutonneuse fever Rickettsia helvetica
» Clothing Tick removal Clothing impregnation Vaccination
» Host-centred methods Habitat manipulation and urban design
» Tick and tick-borne disease surveillance IPM
» Public activities Pesticide applications
» Surveillance and management Research
» Other mosquito-borne viral infections that cause encephalitides
» Malaria Mosquitoes as a pest nuisance
» Dengue haemorrhagic fever and yellow fever
» Dirofilariasis The spread of mosquitoes and mosquito-borne pathogens
» National reporting and Mosquitoes
» Mosquito control and management
» Sanitation and water management
» Adulticiding Larviciding Mosquito monitoring
» Use of predators biological control Passive protection
» Genetic control and transgenic mosquitoes
» Feeding Biology of commensal rodents 1. Description and natural history
» Reproduction and life cycle of commensal rodents
» Behaviour relevant to control
» Movement Biology of commensal rodents 1. Description and natural history
» Population growth and socialization of commensal rodents
» Sewers and drains Association with urban infrastructure 1. Rodents in housing
» Case study 1 – rat bites in Philadelphia: identifying the factors contributing to risk
» Zoonoses of mice Public health risks in urban areas
» Case study 2: Fairhill case study
» Tree squirrels Types, distribution and abundance
» Chipmunks Ground squirrels, antelope ground squirrels and prairie dogs
» Hamsters Voles Types, distribution and abundance
» Beavers Types, distribution and abundance
» Rabbits and hares Types, distribution and abundance
» Francisella tularensis Major rodent- and lagomorph-related bacterial and rickettsial agents
» California group viruses primarily La Crosse virus CTF virus
» Yersiniae Major rodent- and lagomorph-related bacterial and rickettsial agents
» Borrelia burgdorferi s.l. Tick-borne relapsing fever borreliae
» Toxoplasma Toxocara Major rodent- and lagomorph-related parasitic agents
» Babesiae Leptospirae Major rodent- and lagomorph-related parasitic agents
» Bartonellae Rat-bite fever agents
» Flying squirrels Ground squirrels and antelope ground squirrels
» Tree squirrels Voles and other microtine rodents
» Chipmunks Disease associations with particular types of rodents
» Beavers Disease associations with particular types of rodents
» Rabbits and hares Old World mice
» Dormice N ew World rats and mice
» Introduction The impacts of anthropogenic transformations
» Risk factors for rodent- and lagomorph-related diseases Public health impact
» Costs, control and management of infestations
» Control and management of non-commensal rodents and rodent-related diseases
» Conclusions Non-commensal rodents and lagomorphs
» EU community-level authorization of technical grade active ingredients
» Acute toxicity The precautionary principle
» The substitution doctrine Special considerations given to children’s health
» Toxicity end-points Pesticide hazard identification
» Long-term effects Pesticide hazard identification
» Insecticide synergists N eonicotinoid insecticides
» Spot applications Primary exposure of non-professional users and secondary exposures
» Inhalation Routes of exposure
» Incidental oral exposure Routes of exposure
» Exposure potential Steps of pre-market risk assessment of pesticides
» Tiered approaches to exposure estimation: a basis for risk assessment
» Mathematical mechanistic models Empirical models Some existing models
» Statistical mathematical models SOPs and exposure scenario types
» Comparing pesticide risks from residential and dietary exposures
» Residential applicator exposure assessment
» Toxicity end-points and MOS Residential applicator exposure
» Future actions and data development
» Identification Establishment of threshold levels
» Inspection Evaluation of effectiveness
» Develop an IPM plan Employment of two or more control measures
» Definitions of IPM An integrated approach to managing urban insects and rodents
» Case study 3 Case study 4 Case study 5
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