Health & Management / Managing for West Nile Virus Infection / List of hyperlinked Techniques & Protocols:
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Introduction and General Information

Prevention and control of arboviral diseases is accomplished most effectively through a comprehensive integrated mosquito management program; effective mosquito control begins with a surveillance program that targets pest and vector species, identifies and maps the habitats of the immature forms (larvae and pupae) by season, and documents the need for control. (D67, D147)

  • Vector control is most effective when directed at the species responsible for virus transmission. For optimum impact both enzootic/epizootic and epidemic vectors should be targeted. (P32.1.w3)

Habitat management for the control of West Nile Virus acts to reduce the population of vector mosquito species. It includes both large-scale and small scale habitat management for source reduction, and also local management against adults.

  • Source reduction, the alteration or elimination of habitat suitable for mosquito larvae, to prevent mosquitoes from breeding in those locations, remains the most effective and economical method of long-term mosquito control in many habitats. (D67, W175.Nov01.wnv21)
Published Guidelines linked in Wildpro

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Sanitation (Local Source Reduction)

The most important action which can be taken by an individual property owner is to remove from their property "all man-made potential sources of stagnant water in which mosquitoes might breed." (W30.Nov01.WNV3) 
  • Awareness that mosquitoes are able to breed in any puddle that lasts for more than four days is key to local source reduction. (W30.Nov01.WNV3)
  • It is also important to recognise that many species of mosquito, including those which have been implicated in the WN virus epizootic in the USA, lay eggs in standing water with an organic content. (D72)

Local source reduction measures:

The following activities which may be undertaken by individual property owners to prevent mosquitoes from breeding on their property

  • Destroy or dispose of containers that collect and hold water, such as tin cans, old tires, buckets, unused plastic swimming pools or other objects. 
  • Do not allow water to accumulate at the base of flower pots or in pet dishes for more than two days.
  • Drill holes in the bottom of containers which are left outdoors;
  • Clean debris from rain gutters yearly and remove any standing water under or around structures, or on flat roofs. 
  • Check around faucets and air conditioner units and repair leaks or puddles that remain for several days.
  • Eliminate seepage from cisterns, cesspools, and septic tanks.
  • Change water in bird baths and wading pools at least once a week. Stock ornamental pools with top feeding predacious minnows (mosquito fish). These minnows are about one to one and a half inches in length and can be purchased, or native fish may be seined from local streams and creeks. Ornamental pools may be treated with biological larvicides (Bacillus thuringiensis subsp. israelensis or products containing Methoprene, an insect growth regulator) under some circumstances. (W175.Nov01.WNV2)
  • Remove excessive vegetation from ornamental ponds.
  • Fill or drain puddles, ditches and swampy areas, and either remove, drain, treat with biological larvicides or products containing insect growth regulators, or fill tree holes and stumps with mortar.
  • Turn over wheelbarrows and plastic wading pools when they are not in use;
  • Eliminate standing water around animal watering troughs, clean out livestock watering troughs thoroughly at least once a month and preferably flush through twice a week;
  • Irrigate lawns and gardens carefully to prevent excess water that may stand for several days
  • Cleaning and chlorinating swimming pools that are not in use; and 
  • Avoiding letting water collect on the top of swimming pool covers or covers over boats etc.
  • Check around construction sites, including do-it-yourself improvements, to ensure that proper backfilling and grading are present, avoiding drainage problems.
  • Cover rain barrels with screening, or empty weekly.

(D67, D72, D73, P32.1.w23, P32.1.w27, W30.Nov01.WNV3, W175.Nov01.WNV2) 

  • N.B. a study undertaken in Mississippi in 2002 indicated the importance of local source reduction; the greatest increases in the risk of WNV infection were found to be associated with environmental factors favouring mosquito populations, including the presence of a septic tank in the yard, the presence of an ornamental pond, having an abandoned property nearby and having standing puddles nearby. (P48.4.w9)
  • Public education is vital to maximise local source reduction measures (D70, P32.1.w27). See: Education and communication for West Nile Virus

Larger scale sanitation measures:

On a larger scale, sanitation involves efforts such as cleaning or flushing storm drains, removing tire piles, stream restoration, catch basin cleaning etc.

  • "To prevent standing water, federal, state and local governments should maintain the existing drainage structures on their properties such as preserves, sumps, recharge basins, sewage or wastewater treatment facilities, street catch basins, salt marsh ditches, upland streams, ponds, and pools (unless law dictates otherwise). IPM [Integrated Management Plan] strategies to eliminate larval mosquito breeding should be pursued. Privately owned or operated sewer facilities should be maintained in a similar fashion to eliminate larval mosquito breeding." (D72)
  • It is important to ensure that community-level actions are taken to clean up used tire piles and other large trash/rubbish sites and to drain large pooled water sources with vegetated edges and a high organic content. (V.w42)
  • In some situations open breeding sites may be filled with soil to eliminate standing water. (D73)
  • Standing waters such as salt-marshes, sewage lagoons, dairy lagoons, storm-water retention ponds and farm dug-outs can be modified to be unsuitable for mosquito breeding by good design, such as shorelines which slope steeply and are gravelled, manipulation of water levels and control of emergent vegetation.
  • Existing sites may have shallow and marginal areas altered so they are deeper with an increased slope; this decreases the establishment of emergent vegetation.
  • Wide ditches along major roads may be modified to make them less efficient mosquito breeding sites by running a narrower, deeper ditch through the centre. 
  • Shallow depressions and unnecessary ditches that hold water may be filled or their drainage improved. (D73)
  • Scraping sediment from the bottom of roadside ditches may make them less attractive mosquito habitat. (D73)
  • Patches of flooded habitat near to roadside ditches may be drained into the ditch, which is more accessible for further control if required (D73)
  • If ditches do not flow and contain stagnant water for a week or more they may produce large mosquito populations; persons noting such ditches should report them to an appropriate authority (e.g. a Mosquito Control Office or Public Health Office). (W175.Nov01.WNV2)
  • N.B. local wildlife officials should be consulted prior to carrying out source reduction to ensure that the proposed measures are acceptable from the point of view of wildlife habitat. 

    (D70, D72, D73, P32.1.w27, V.w42, W175.Nov01.WNV)

Associated techniques linked from Wildpro

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Large Scale Water Management

Avoiding the presence of standing stagnant nutrient-rich water is particularly important to avoid breeding mosquitoes. (P32.1.w8)

Depending on the water body in question it may be possible to use draining, filling, controlled fluctuation of water levels and shoreline alterations (to make them smooth and free of vegetation) to reduce mosquito breeding. (D71

  • Draining of mosquito habitat, particularly in urban settings, is commonly an effective control measure. (P32.1.w8)

The following information on water management is quoted directly from the CDC Epidemic/Epizootic West Nile Virus in the United States: Revised Guidelines for Surveillance, Prevention and Control (D67): [Text copied directly]

Water management for mosquito control is a form of source reduction that is conducted in fresh and saltwater breeding habitats. Water management programs for vector control generally take two forms: 

a. Impoundment Management

Impoundments are mosquito-producing marshes around which dikes are constructed, thereby allowing water to stand or to be pumped onto the marsh surface from the adjacent estuary. This eliminates mosquito oviposition sites on the impounded marsh and effectively reduces their populations. Rotational Impoundment Management (RIM) is the technique developed to minimally flood the marsh during the summer months and then use flapgated culverts to reintegrate impoundments to the estuary for the remainder of the year, thereby allowing the marsh to provide many of its natural functions. Although impoundments usually achieve adequate control of salt-marsh mosquitoes, there are situations where impoundments can collect stormwater or rainwater and create freshwater mosquito problems which must be addressed using other techniques.

b. Open Marsh Water Management (OMWM)

Ditching as a source reduction mosquito control technique has been used for many years. Open marsh water management is a technique whereby mosquito producing locations on the marsh surface are connected to deep water habitat (e.g., tidal creeks, deep ditches) with shallow ditches. Mosquito broods are controlled without pesticide use by allowing larvivorous fish access to mosquito-producing depressions. Conversely, the draining of these locations occurs before adult mosquitoes can emerge. OMWM can also include establishing or improving a hydrological connection between the marsh and estuary, providing natural resource enhancement as well as mosquito control benefits. The use of shallow ditching (ditches approx. 3 ft. or less in depth rather than the deep ditching used in years past) is considered more environmentally acceptable because with shallow ditches, fewer unnatural hydrological impacts occur to the marsh.

Associated techniques linked from Wildpro

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Reducing Habitat for Adult Mosquitoes

Local vegetation clearance, including cutting down weeds around houses and regular mowing of lawns, has been suggested as a method of reducing resting places for adult mosquitoes in the vicinity of houses. (W175.Nov01.WNV2)
Associated techniques linked from Wildpro

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Authors & Referees

Authors Debra Bourne (V.w5)
Referee Suzanne I. Boardman (V.w6); Becki Lawson (V.w26)

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