Indoor residual spraying

The World Health Organization (WHO) recommends IRS as one of three primary means of malaria control, the others being use of insecticide treated bednets (ITNs) and prompt treatment of confirmed cases with artemisinin-based combination therapies (ACTs).{{cite web|url=https://www.who.int/topics/malaria/en/|title=WHO – Malaria|last=World Health Organization|access-date=2008-11-22}} While previously the WHO had recommended IRS only in areas of sporadic malaria transmission, in 2006 it began recommending IRS in areas of endemic, stable transmission as well.{{cite web|url=http://www.pops.int/documents/ddt/Global%20status%20of%20DDT%20SSC%2020Oct08.pdf|title=Global status of DDT and its alternatives for use in vector control to prevent disease|last=van den Berg|first=Henk|date=October 23, 2008|publisher=Stockholm Convention/United Nations Environment Programme|access-date=2008-11-22|url-status=dead|archive-url=https://web.archive.org/web/20101217022138/http://www.pops.int/documents/ddt/Global%20status%20of%20DDT%20SSC%2020Oct08.pdf|archive-date=December 17, 2010}}

According to the WHO:[https://iris.who.int/bitstream/handle/10665/69386/WHO_HTM_MAL_2006.1112_eng.pdf?sequence=1&isAllowed=y Indoor Residual Spraying: Use of Indoor Residual Spraying for Scaling Up Global Malaria Control and Elimination.] World Health Organization, 2006.

{{cquote|[N]ational governments should:

1. Introduce and/or scale up coverage of targeted IRS as a primary malaria control intervention in countries where available data indicates that it can be effective towards achieving malaria targets.
2. Take all necessary steps to ensure effective implementation of IRS interventions, including selecting the appropriate insecticide, spraying where and when necessary and sustaining a high level of coverage, and to prevent unauthorized or un-recommended use of public health insecticides.
3. Strengthen the managerial capacity of national malaria control programmes and improve human, technical and financial resources for the timely delivery and high coverage of effective interventions including IRS, with adequate monitoring and evaluation.}}

Furthermore, for IRS to be effective:

1. There must be a high percentage of sprayable surfaces within each dwelling.
2. The vector (mosquitos) must feed or rest indoors.
3. The targeted vectors must be susceptible (i.e. not resistant) to the insecticide being sprayed.

The WHO further states that "insecticide susceptibility and vector behaviour; safety for humans and the environment; and efficacy and cost-effectiveness" are factors that must be considered when selecting an insecticide for IRS.

Currently, the WHO has approved 13 different insecticides for the IRS.

According to 2010 Cochrane review, IRS is an effective strategy for reducing malaria incidence. It is about as effective as using insecticide treated nets (ITN)s, though ITNs may be more effective at reducing morbidity in some situations.{{cite journal |vauthors=Pluess B, Tanser FC, Lengeler C, Sharp BL |title=Indoor residual spraying for preventing malaria |journal=Cochrane Database Syst Rev |volume=4 |issue= 4|pages=CD006657 |year=2010 |pmid=20393950 |doi=10.1002/14651858.CD006657.pub2 |editor1-last=Lengeler |editor1-first=Christian|pmc=6532743 }}

Few studies have directly compared the cost effectiveness of IRS directly with other methods of malaria control. A study from 2008 assessed the cost effectiveness of seven African anti-malaria campaigns: two IRS campaigns and five insecticide treated bednet (ITN) distribution campaigns. The authors found that on a cost-per-child-death-averted basis, all were about the same, but the ITN campaigns were slightly more cost effective.{{cite journal|last=Yukich|first=Joshua O|date=17 December 2008|title=Costs and consequences of large-scale vector control for malaria|journal=Malaria Journal|volume=7|issue=258|pages=258|doi=10.1186/1475-2875-7-258|pmid=19091114|pmc=2625363|display-authors=etal |doi-access=free }}

With regard to the cost effectiveness of various pesticides vis-a-vis each other for IRS, historically DDT has been considered the most cost effective, mainly because it lasts longer than alternatives and therefore dwellings can be sprayed less frequently. But actual studies on cost effectiveness are lacking, and none have taken into account the adverse health and environmental effects of DDT or its alternatives. The United Nations Environment Programme (UNEP) concluded in 2008 that "IRS with DDT remains affordable and effective in many situations but, with regard to the direct costs, the relative advantage of DDT vis-à-vis alternative insecticides seems to be diminishing. The contextual evidence base on cost-effectiveness needs strengthening, and the external costs of DDT use vis-à-vis alternative insecticides require a careful assessment."

File:Mosquitoes-Killedy-By-DDT-Lake-Victoria.JPG

For IRS to be effective, at least 80% of premises (houses and animal shelters) in an area must be sprayed, and if enough residents refuse spraying, the effectiveness of the whole program can be jeopardized. Many residents resist spraying of DDT in particular. This is due to a variety of factors, including its smell[http://www.mindfully.org/Health/Malaria-New-Strain.htm In Malaria War, South Africa Turns To Pesticide Long Banned in the West] {{webarchive|url=https://web.archive.org/web/20071013113406/http://mindfully.org/Health/Malaria-New-Strain.htm |date=2007-10-13 }}, Roger Thurow, Wall Street Journal, July 26, 2001 and the stains it leaves on the walls.[http://news.bbc.co.uk/2/hi/africa/1677073.stm DDT and Africa's war on malaria], BBC{{cite journal |vauthors=Mabaso ML, Sharp B, Lengeler C |title=Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying |journal=Trop. Med. Int. Health |volume=9 |issue=8 |pages=846–56 |year=2004 |pmid=15303988 |doi=10.1111/j.1365-3156.2004.01263.x|doi-access= }}[http://ipmworld.umn.edu/chapters/curtiscf.htm Control of Malaria Vectors in Africa and Asia] {{webarchive|url=https://web.archive.org/web/20071002124232/http://ipmworld.umn.edu/chapters/curtiscf.htm |date=2007-10-02 }} C.F.Curtis

While that stain makes it easier to check whether the room has been sprayed, it causes some villagers to resist the spraying of their homes{{Cite news | last = Gladwell | first = Malcolm | author-link = Malcolm Gladwell | title = The Mosquito Killer | newspaper = The New Yorker | date = July 2, 2001 | url = http://www.gladwell.com/2001/2001_07_02_a_ddt.htm | url-status = dead | archive-url = https://web.archive.org/web/20090206205027/http://gladwell.com/2001/2001_07_02_a_ddt.htm | archive-date = February 6, 2009 }}.[http://www.cato.org/pubs/pas/pa513.pdf South Africa's War against Malaria Lessons for the Developing World], Richard Tren and Roger Bate, Cato Institute or to resurface the wall, which eliminates the residual insecticidal effect. Pyrethroid insecticides are reportedly more acceptable since they do not leave visible residues on the walls.

In addition, DDT is not suitable for this type of spraying in Western-style plastered or painted walls, only traditional dwellings with unpainted walls made of mud, sticks, dung, thatch, clay, or cement.{{cite journal |vauthors=Hargreaves K, Hunt RH, Brooke BD, etal |title=Anopheles arabiensis and An. quadriannulatus resistance to DDT in South Africa |journal=Med. Vet. Entomol. |volume=17 |issue=4 |pages=417–22 |year=2003 |pmid=14651656 |doi=10.1111/j.1365-2915.2003.00460.x|s2cid=22748077 }} As rural areas of South Africa become more prosperous, there is a shift towards Western style housing, leaving fewer homes suitable for DDT spraying, and necessitating the use of alternative insecticides.

Other villagers object to DDT spraying because it does not kill cockroaches or bedbugs; rather, it excites such pests making them more active, so that often the use of another insecticide is additionally required. Pyrethroids such as deltamethrin and lambdacyhalothrin, on the other hand, are more acceptable to residents because they kill these nuisance insects as well as mosquitoes. DDT has also been known to kill beneficial insects, such as wasps that kill caterpillars that, unchecked, destroy thatched roofs.

As a result, Mozambique's chief of infectious disease control, Avertino Barreto, says that resistance to DDT spraying is "homegrown", not due to "pressure from environmentalists". "They only want us to use DDT on poor, rural black people," he says. "So whoever suggests DDT use, I say, 'Fine, I'll start spraying in your house first.{{'"}}

As discussed above, DDT is one of several insecticides currently approved by the WHO for use in malaria control. The following table shows recent per country use of DDT for IRS. Unless otherwise noted, data for 2003–2007 is from the 2008 Stockholm Convention/UNEP monograph on the current status of DDT, 2008 data is from the WHO's World Malaria Report 2009,World Health Organization, [https://web.archive.org/web/20091224160716/http://www.who.int/malaria/publications/atoz/9789241563901/en/index.html World Malaria Report 2009], 2009. and 2009 data is from the 2010 report of the Stockholm Convention's DDT expert group.{{cite web|url=http://chm.pops.int/Convention/COP/hrMeetings/COP5/COP5Documents/tabid/1268/language/en-GB/Default.aspx|title=UNEP/POPS/COP.5/5. Report of the expert group on the assessment of the production and use of DDT and its alternatives for disease vector control.|last=DDT Expert Group of the Stockholm Convention|date=15 Dec 2010|publisher=United Nation Environment Programme|access-date=11 April 2011}} The World Malaria Report 2009 does not report the amount of DDT used in each country, only whether it is used or not. Accordingly, countries are listed as using 0 or "some" DDT. Use statistics for 2009–2011 are available from a report of Stockholm Convention's DDT Export Group{{Cite web | url=http://chm.pops.int/Implementation/PesticidePOPs/DDT/DDTMeetings/DDTEG42012/tabid/2942/mctl/ViewDetails/EventModID/874/EventID/338/xmid/9462/Default.aspx | title=DDT-Eg4}}

{{Reflist|30em}}

• [https://web.archive.org/web/20090518051854/http://apps.who.int/malaria/docs/WHO-TRS-936s.pdf MALARIA VECTOR CONTROL AND PERSONAL PROTECTION], WHO Technical Report Series No. 936. 2006.

Category:Pesticides

Category:Malaria