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Vector Control Methods Module 3A Introduction

Vector Control Methods Module 3A Introduction. Decision to carry out vector Control . Common Vectors and their control. Regular assessment needed for immediate control Must identify vector and understand life cycle for effective control.

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Vector Control Methods Module 3A Introduction

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  1. Vector Control MethodsModule 3AIntroduction

  2. Decision to carry out vector Control

  3. Common Vectors and their control • Regular assessment needed for immediate control • Must identify vector and understand life cycle for effective control. • Distinguish – and prioritise - between disease risk and nuisance • Use environmental controls where possible • Only use chemical spraying as last resort, as • Frequent use causes resistance • Can be poisonous • Environmentally polluting

  4. Planning a vector control campaign • Strategy • Identify vector with certainty • Determine environmental factors involved • Map breeding sites & population spread • Assess risk of disease epidemic • Determine objectives – acceptable levels and control methods • Determine indicators by which to measure the impact of the campaign

  5. Vector control campaign: Strategy • Identify vector with certainty • Determine environmental factors involved: • Breeding sites • Feeding areas • Map breeding sites & population spread • Assess risk of disease epidemic • Determine any chemical resistance of vectors • Plan areas to be covered by campaign

  6. Vector control campaign: Objectives Environmental controls alone? Hygiene promotion campaign? Chemical response needed? A combination may be the optimum solution to reduce the risk of epidemics

  7. Vector control campaign: Indicators

  8. Vector control campaign: Planning the programme Before implementing control measures, ensure: • Objectives are clearly defined • Control method options are clearly defined • Host country regulations & role understood • Sufficient resources & personnel • Supervision & training requirements met • Logistics arranged • Role of affected community clarified

  9. Example vector control campaign Source: UNHCR, 1997.

  10. Example vector control campaign • Divide area into operational zones small enough to be treated by a team (4-5 people) • One worker can use 8-10 hand-sprayers a day, each containing 8 litres of solution • With an application rate of 40 ml of solution per m2, one worker can treat about 1,800 m2 a day, or 36 dwellings of 50 m2 each.

  11. Vector control practical Exercise 1: Calculate the amount of permethrin (50% EC formulation) needed to impregnate 200 mosquito nets with a dose of 0.2 g/m2. The net dimensions are 2m height by 2m length, and 1m width, with an overlap band of 0.3m width.(N.B. EC = emulsifiable concentrate, to be diluted with water).

  12. Vector control practical Exercise 2: In a malaria outbreak in a tented camp area, your cluster has decided to treat all the dwellings with a residual spraying of pyrethroid compound to reduce the mosquito population. You need to spray 1500 shelters with deltamethrin, which is provided in a 2.5% WP (wettable powder) formulation. The shelters have an average surface area of 75m2. Calculate the amount of deltamethrin and the quantity of water needed. (N.B. 0.04 l/m2 solution is a standard coverage value for spraying insecticide).

  13. Summary & conclusions • Wrap-up session • Outstanding Issues • Sources of further information

  14. Terms for how vectors behave: • Anthropophilic: bite humans • Zoophilic: bite animals • Endophagic: bite indoors • Exophagic: bite outdoors • Endophilic: rest indoors after a blood meal • Exophilic: rest outdoors after a blood meal

  15. Information needed for design of prevention strategies: Vectors and their behaviour Is there a risk of an outbreak? Who are the most at risk? Feasibility (security, access, funding, available materials, adequate human resources, local capacity)? People’s behaviour (mobile/fixed, sleep inside/outside etc)? Type of shelter used? Strong preferences/dislikes? Previous experiences

  16. Which intervention is the most cost effective? IRS is much cheaper for one off interventions. Must repeat IRS every 6-10 months in area of constant, high transmission Over 2 years it may be cheaper to use ITNs and the families will have a greater level of control and responsibility. For refugees and IDPs use of insecticide treated plastic sheeting can be effective and economical as it provides shelter and control of malaria mosquitoes and flies

  17. Challenges to controlling VBDs in emergencies: Efficacious tools Ensuring access to efficacious tools for prevention and treatment Acceptability - a major key to effectiveness of the tools Suitability - there on time & fit “Know How” to use correctly

  18. Current wisdom for main VBD control Early detection and confirmatory diagnosis Effective treatment Intermittent preventative malaria treatment (IPT) of Pregnant women Long lasting insecticide treated nets (LLINs) to protect from vector bites(malaria, filariasis + leishmaniasis) Indoor Residual Spaying (IRS) of dwellings to kill resting insect vectors(malaria and rift valley fever)

  19. Larvicide to kill larval forms of vectors in surface water breeding sites(dengue and malaria) • ITPS to provide duel protection (shelter and LL IRS) for displaced families(malaria and flies) • Tsetse fly traps (sleeping sickness)

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