1. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Greater Mekong Subregion Malaria Elimination Training. The Imerial Mae Ping Hotel, Chiang Mai, Thailand 10 – 21 st August 2015. Approaches and interventions for malaria vector control in Greater Mekong Subregion. Dr Rabindra Abeyasinghe (MVP) Regional Office for the Western Pacific Approaches and interventions for malaria vector control in Greater Mekong Subregion. Dr Rabindra Abeyasinghe (MVP) Regional Office for the Western Pacific

2. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand.

3. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Outline List the different vector control methods and their role in malaria elimination Describe the technical and operational issues related to vector control measures

4. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Understanding the life cycle of malaria vectors – Key points for control

5. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Vector bionomics Factors defining the bionomics: Larval breeding sites, feeding and resting behaviours including peak biting times, insecticide susceptibility and behavioural resistance Larval breeding site characteristics: light intensity, salinity, turbidity, flow or movement, vegetation, size, natural or man made Feeding and resting behaviours: feeding habit, biting habit, biting time, pre-feeding and post-feeding resting sites

6. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Use of bionomics for vector control Most control interventions are based on exploiting the bionomics of vectors. Hence it is imperative to know and understand the bionomics of major vector species. Monitoring and evaluation of VC interventions should be closely linked to epidemiological information and review of vector bionomics.

7. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Equilibrium Relationship Between prevalence and vectorial capacity

8. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Vectorial capacity The expression for the definition of vectorial capacity can be divided into 5 stages: –The primary, infective, case is bitten by a certain number of mosquitoes per day (ma) or the man-biting rate (bites per man per night by vector population) –Man biting habit (a) –Some of these mosquitoes get infected (c). –Some of these mosquitoes survive the extrinsic incubation period so they are alive and infectious (e -ng ). –They bite a certain number of humans before they die (a/g). –Some of these humans get infected (b). C = ma 2 bce -ng g

9. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Effects of control interventions Long lasting insecticidal nets reduce m, a, and 1/g (increase g) Indoor Residual Spraying reduces m and 1/g (increases g), it may also reduce a if the insecticide has a repellent effect; Space spraying, source reduction and larviciding reduce m; Reduction of man-vector contact reduces a; Treatment of cases increases r (decreases 1/r).

10. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Effects of Parameters on C and R 0 Reduction of m reduces C (and R 0 ) linearly. Reduction of 1/r reduces R 0 linearly. Reduction of a result in a squared reduction in C (and R 0 ). Increase of g is amplified much more by the exponential form of the survival of the mosquito through the extrinsic incubation period, e -gn, in addition to the reduction of the longevity 1/g. C = ma 2 bc e -ng R 0 = ma 2 bc e -ng g rg

11. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Malaria vector control methods 1. Reducing human-vector contact –Insecticide-treated mosquito nets (ITN) –Improved housing –Repellents and mosquito coils 2. Adult mosquito control –Insecticide-treated mosquito nets (ITN) –Indoor residual spraying (IRS) –Space spraying 3. Larval control –Larviciding –Source reduction –Larvivorous fish

12. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Insecticide treated nets ITN programmes may be used; –as a method of personal protection for high risk groups, –for transmission control with a target of high coverage exceeding 80% of the entire population. Advantages of insecticide-treated nets –Low cost –No need for special equipment –Few organization and logistical problems –Low amount of insecticide needed –Compatibility with local customs –Suppression of the population of bed bugs, head lice and nuisance insects –Protection against cold, dust, rats and snakes –Community-based

13. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Limitations of ITN programmes Exophilic and exophagic mosquitoes decrease the effectiveness For people who have allergies the use of pyrethroid- impregnated nets is limited Lack of participation of groups at risk may limit the effectiveness

14. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Components of ITN programmes Following information should be considered in planning, training, implementing and evaluating ITN programmes; –What are the behavioural patterns of the vectors? Exo-/Endophagic/peak biting periods/sleeping patterns/ are people outdoors (outside ITNs) at times when mosquitoes bite most –Night-time movements and habits of people likely to affect exposure to vectors, including the time they go to bed? (This will vary with age, sex, and occupation). –Attitudes of the people towards the use of nets? –Preference for size, shape and colour of the nets? –Who uses nets already? Are there seasonal variations in net use patterns? –How do people react to insecticide use? –What is the economic status of most people? (This will affect net ownership, the ability to pay for insecticides and net (re)treatments.)

15. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Long Lasting Insecticidal Nets Advantages of LLINs –No re-treatment (4–5 years) –Storage of insecticide not required –Direct handling of insecticides avoided –Reduced insecticide use –Reduced environmental hazard Disadvantages of LLINs –Need for removal and safe disposal of old nets at the end of their useful lifespan –Potential for the development of insecticide resistance in vectors

16. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Estimation of the number of nets needed When the size of the target population has been estimated, the number of nets needed to cover the target population should be calculated. It is generally assumed that one net can cover two people so if the target population in an endemic malaria area is 100 000, the number of nets needed to cover the target population is 100 000 / 2 = 50 000.

17. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Conditions for use and effectiveness of IRS IRS is recommended only where: –a majority of the vector population is endophilic, –the vector population is susceptible to the chosen insecticides, –a high percentage of the houses or structures in the operational area have adequate sprayable surfaces, –spraying is done correctly. Mosquitoes rest in various locations during the gonotrophic cycle. Resting takes place indoors in human habitations, in animal shelters and outdoors on vegetation. The preferred vector resting sites in houses are walls, eaves, under furniture, and cool, dark, humid places.

18. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Indications for IRS in malaria control the control of epidemics detected in the early stages of development, where spraying can be done early enough to cut off peak transmission; the control of seasonal transmission in areas with high malaria mortality, morbidity, and disease severity in order to reduce peaks of incidence; Focal spraying for elimination and prevention of re-introduction; special risk situations, (e.g. non-immune population groups temporarily exposed to transmission risks) such as refugee camps, settlers in development project areas, labour camps, and army and police posts ; the reduction of transmission and the curtailment of the spread of drug-resistant parasites in areas with major drug resistance problems.

19. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Advantages & limitations of IRS Advantages of IRS –Very effective for species with endophilic and endophagic behaviour –More effective on vectorial capacity than other measures Limitations of IRS –High cost –Requires well trained personnel –In long term use the community participation may decrease –Due consideration should be given to the safe disposal of excess insecticide –Potential for the development of insecticide resistance in vectors

20. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Integrated Vector Management – a tool for preventing re-introduction and sustaining malaria free status Integrated Vector Management is a decision-making process for the management of vector populations, so as to reduce or interrupt transmission of vector-borne diseases.

21. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Components of IVM Selection of methods based on knowledge of local vector biology, disease transmission and morbidity Utilization of a range of interventions, often in combination and synergistically Collaboration within the health sector and with other public and private sectors that impact on vector breeding

22. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Components of IVM… Engagement with local communities and other stakeholders A public health regulatory and legislative framework Rational use of insecticides Good management practices

23. Transmission of malaria and measures of transmission intensity, 10 th – 21 st August 2015, The Imperial Mae Ping Hotel, Chiang Mai, Thailand. Thank you