Integrated vector control approach Dr Kulrajat Bhasin.


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Integrated vector control approach Dr Kulrajat Bhasin.

  1. 1. Integrated vector control approach Dr. Kulrajat Bhasin 1
  2. 2. Plan of presentation • • • • • • • • Introduction Principles of vector control Integrated vector control approach. Selection criteria for vector control measures Evolution of Integrated vector control approach. Integrated vector control approach for mosquito. Key elements of an IVC Strategy. References. 2
  3. 3. Introduction • Vector - definition • Common vectors and diseases - Mosquito : Malaria, filaria, viral encephalitis e.g.., Japanese encephalitis, viral fevers e.g.., Dengue, west Nile. - Housefly : typhoid and Para typhoid fever, diarrhea, dysentery, cholera, gastroenteritis, amoebiasis, helminthic infestations, poliomyelitis, conjunctivitis, trachoma, anthrax, etc. - Sand fly : Kala azar, oriental sore, sand fly fever, oraya fever • Transmission of disease- Direct contact, mechanical, biological (propagative, cyclopropagative, cyclodevelopmental). 3
  4. 4. Principles of vector control 1. Environmental control: the best approach as the results are likely to be permanent. 2. Chemical control 3. Biological control 4. Genetic control 5. Newer methods like insect growth regulators, chemosterilents, pheromones 4
  5. 5. Integrated vector control approach • No single method is likely to provide a solution in all situations. The present trend is to adapt a IVC approach. • Vector control approach combining two or more methods with a view to obtain maximum results with minimum efforts. • “Integrated vector control approach is the present trend for vector control defined as utilization of all appropriate technological and management techniques to bring out an effective degree of vector suppression in a cost effective manner and also to avoid the overuse of one of the methods”. • Selection of methods is not possible without detailed field information on the ecology, bionomics of vectors, role in disease transmission. 5
  6. 6. Life cycle of Mosquito 4 Common stages in development namely : 1. Egg, 2.Larva , 3.pupa and 4. adult 6
  7. 7. Habits of vectors A knowledge of these habits is essential from the point of view of controlling them as well as the part they play in transmission of disease Mosquito Housefly 1. • • Feeding habits: males never bite and subsist on plant juices females on the other hand are hematophagus 2. Time of biting: generally evening (aedes fearless females) 3. Resting habits: exophyllic . Vegetations, shrubs , tree holes, cattle sheds. 4.Breeding habits: anopheles-prefer clean water culicines - dirty polluted water. aedes - artificial collections of water( rainy season) mansonia – aquatic plants( water hyacinth 5. Hibernation: in winters or when condns not favorable in adult stage 6. Dispersal : not far unless swept away with air currents( yellow fever) 7. Life span : normally varies from 8 – 34 days but males as a rule are short lived 1. • • • • • • • 2. 3. 4. 5. 6. 7. Breeding habits : in order of importance are Fresh horse manure Human excreta Manure of other animals Garbage Decaying fruits and vegs Organic rubbish dumps Liquid wastes scattered on ground Feeding habits : does not bite, mechanical transmission. Cannot eat solid food so vomits and making a soln sucks in a liquid state Restlessness : moves to and fro. Vomit drop : fly vomits frequently which is a culture of disease agents Defecation : habit of defecating depositing bacteria on exposed food Resting habits : on vertical surfaces and hanging objects and tendency to fly towards light. Dispersal : up to 4 miles or more from point of origin 7
  8. 8. Selection criteria for vector control measures 1. Effectiveness. 2. Safety. 3. Simplicity of use- indications, contraindications, skills, difficulties in using. 4. Cost 5. Time and effort 6. Type of benefit. 7. Social acceptability- local context. 8. Support requirements. 8
  9. 9. Evolution of the integrated vector control • Vector control has been a part of malaria control activities since the early 20th century. • During the pre-DDT era, reduction of vector mosquitoes largely relied on larviciding & environmental management of breeding habitats. • 1950s- DDT and other insecticides were extensively used. • 1970s, development of insecticide resistance, poor human acceptance and environmental concerns against the use of insecticides. • This led to a rethinking in vector control strategies. • 1980s, WHO proposed an Integrated Vector Control (IVC) strategy based on the principles of Integrated Pest Management in agriculture. 9
  10. 10. Integrated vector control approach for mosquito Mosquito Control Measures Anti larval measures 1. Anti adult measures Environmental 1. Space sprays control 2. Residual 2. Chemical sprays control 3. Genetic control 3. Biological control Protection against mosquito bites Legislative control 1. Mosquito nets Civic laws 2. Screening 3. Repellents 10
  11. 11. Anti-larval measures Environmental control The most important step in reducing the number of mosquitoes 1.Elimination of breeding places (source reduction) like,  Filling and leveling  Drainage of breeding places  Water management 2.Proper disposal of refuse other wastes. 3.Cleanliness in and around the houses . Community involvement & multisectoral coordination 11
  12. 12. Chemical Control Larvicide Formulation Duration Petroleum oil- Diesel oil and Larvicidal oil Suspension 1-2 weeks Paris green Granules 2 weeks Organophosphorus compounds Abate Malathion Fenthion Chlorpyrifos Emulsifiable conc Emulsifiable conc Emulsifiable conc EC, Suspension 2-11 weeks 1-3 weeks 1-2weeks 2-4 weeks Insect growth regulators- Diflubenzuron, Methoprene, Pyriproxyfen Suspension/ Granules 4-8 weeks Bacterial LarvicidesBacillus thuringiensis H-14 B. Sphaericus EC/ Granules 1-2 weeks 2-8 weeks 12
  13. 13. • Highly toxic to insect larvae or pupae, interfering with development into adults. Used in large scales in USA.. • Costly & have restricted availability -not used in India. • Particularly useful if insects have developed resistance to insecticides or because of their environmental effect. • Safe to human beings and environment. 1. Juvenile hormone analogues: prevent development of larvae into pupa or pupae into adult. Ex. Methoprene 2. Chitin synthesis inhibitors: interfere with moulting process, killing larvae when they moult. Act more rapidly. Ex. Diflubenzuron and Triflumoron. 13
  14. 14. • Expanded form of polystyrene granules - available commercially with diameter ranging from 0.6 to 2.5 mm. • Increased by boiling. • They do not decay and remain floating for years. • Spread on surface of water to form floating layer. A layer of 1-2 cm is sufficient if it covers the surface. • Easily blown or washed away- only sites where water remains confined -wells. • Used safe in drinking water 14
  15. 15. Biological Control • Natural enemies into the environment-includes Insects, Viruses, Bacteria, Protozoa, Fungi and Fish. • Only two of them have become widely employed. They are Larvivorous fish and Biolarvicides. 15
  16. 16. 1.Larvivorous fish • Feed on mosquito larvae. • Easy, practical, cheap; they have no food value. • They should have the following characteristics – Preference for mosquito larvae over other types of food – Small size – High reproduction rate – Tolerance to pollution, temperature fluctuation & transportation. • Two species are widely usedGambusia - clean water, tolerate wide range of temperature, pH water salinities. Guppy- Polluted water, cannot <10 degree C. 16
  17. 17. • Useful in ornamental tanks, wells, Garden ponds, fountains, swimming pools, large water collection. • Approximately 5 fish per sq.m of water surface. Advantages a. Long term effective control measure. b. Cost effective. c. Environmentally safe. d. Controls variety of mosquito species. Disadvantages a. Effective when large numbers eventually establish themselves. b. takes 1-2 months; not suitable - quick anti larval measures are needed. 17 c. less effective in waters with much vegetation or floating garbage.
  18. 18. • Bacteria for the control of mosquito larvae. Bacillus thuringiensis H 14 and Bacillus sphaericus. • Available as wettable powder and granules which contain bacteria, spores and toxic crystals. • Safe to environment , human being and animals but are expensive. Bacillus thuringiensis H 14 • Gram positive, spore forming bacteria which is specifically acts against mosquito larvae. • Produces endotoxin which after ingestion causes gut paralysis & leakage of contents into body cavity leading to death. 18
  19. 19. • • It is applied at 0.5 gm/sq.m 250gm of B. thuringiensis is mixed with 10 L of water to make 2.5% suspension & sprayed at 1L over 50 sq.m every 2 weeks. Bacillus sphaericus • It also produces toxin. • It is more effective in polluted water - suitable for treatment of breeding sites of Culex. • 500gm of B. sphaericus with 10 L of water to make 5% suspension & it is sprayed at 1 L over 50 sq.m. every 3 weeks. Others BiolarvicidesFungi- Coelomyces, Culicinomyces, Nematodes – Romanomermis cluicivorax and R. iyengari. 19
  20. 20. Space sprays – Space sprays are those where the insecticidal formulations is sprayed into the atmosphere in the form of mist or fog. 1. Thermal fog. 2. ULV cold aerosols. – Done where immediate results are needed like during outbreak of disease to bring down mosquito population drastically. – Exophillic vector species. 20
  21. 21. Space sprays (contd) Sl. no Name of Insecticide Formulation Preparation of formulation Equipment used Remarks 1 Pyrethrum extract 2.0% extract 1:19 i.e., 1 part of 20% pyrethrum extract in 19 parts of kerosene Flit pump or hand operated fogging machine Used for indoor spray 2. Technical Malathion 5 parts of tech. Malathion in 95 parts of Diesel oil Vehicle mounted thermal fogging machine Speed of vehicle 6 km/hour Outdoor thermal fogging Used for outdoor spray 3 Deltamethrin 1 litre in 199 litre Diesel 1.25ULV Thermal fogging machine Outdoor thermal fogging Used for outdoor spray 21
  22. 22. Advantages of space sprays • Immediate effect - suitable for control of disease outbreak. • Less insecticide is required for one application. • Kills exophillic species of mosquito. Disadvantages of Space sprays • Effect lasts for shorter period- repeated at least once a week. • The cost of equipment, operational and maintenance - high; • Needs specially trained staff for maintenance and repair. • May cause pollution. • Problems with acceptability. 22
  23. 23. Indoor Residual Sprays • Application of insecticides to surfaces so that the insecticide particles remain on the surface in the form, size and quantity suitable for insects to pick up on contact and sufficient to exert a lethal effect over a long period. • Endophillic species. Knapsack sprayer Compression pneumatic sprayer 23
  24. 24. Indoor Residual Sprays Sl. Name of the insecticide No. Dosage Residual effect in weeks 1 DDT 50% wp 1 gm 10 -12 2 3 4 BHC 50% wp Malathion 25% wp Deltamethrin 2.5% wp 200 mg 2 gm 20 mg 6–8 6–8 10 -12 5 6 7 Alpha Cyperthrin 5.0% wp Cyfluthrin 10% wp Lamdadcyhalothrin 10% wp 25 mg 25 mg 25 mg 10 -12 10 -12 10 -12 8 9 Fenitrothion 40% wp Primiphs-methyl 25% wp 1 gm 2 gm 6–8 6-8 24
  25. 25. 1. May leave visible deposits on walls . 2. Non acceptability. 3. Painting or re-plastering of walls after application reduces or eliminates efficacy of insecticides. 4. People may be reluctant to allow stranger into their houses. 25
  26. 26. • Methods such as 1. sterile male technique 2. Cytoplasmic incompatability 3. Chromosomal translocations 4. Sex distortion 5. Gene replacement Limitations: 1. Lack of mating competitiveness released males. 2. Immigration of fertile females from regions close to the release sites. 26
  27. 27. • Reallocation or introduction of cattle or domestic animals between settlements and mosquito breeding i.e. ring of cattle sheds on the outskirts of a village with houses in the center. • Many mosquito prefer animal blood than human blood and hence decreases biting of human and transmission of disease. • In Japan it is proved to be effective against Culex. 27
  28. 28. a. Mosquito Nets • Mosquito bite during sleep. They also protect against other creatures like spiders, cockroaches, lizards and rats. • Best pattern is rectangular net. • Size of the openings in the net is should not exceed 0.0475 inch in any diameter. The number of holes in one square inch is usually 150. Disadvantages of Untreated Nets 1. Mosquito can feed when body makes contact with the net. 2. Hungry mosquito wait on or near the net until net is opened. 3. After failing to get through the net Mosquito are diverted to unprotected people sleeping nearby. 28
  29. 29. Insecticides Treated bed Nets • • • • Provide better and effective protection by not only preventing mosquito bites & also killing them. They are prepared by soaking the net in insecticidal solution & dried. Nylon nets are preferred - more durable, insecticide stays longer duration and quicker in drying after impregnation. Synthetic Pyrethroids are used for impregnation. Permethrin,Deltamethrin, Cyfluthrin and Lambdacyhalothrin are used. 29
  30. 30. b. Repellents • Mainly used for application on exposed parts of skin. • They act by preventing human-insect contact and do not knock down or kill. • Chief advantage is short duration of protection. Useful for Plantation workers, Army people, Labors who work outdoor at night and Travelers. • N-N-Diethyl-3-toluamide (DEET),indalone, dimethyl pthalate, dimethyl carbate. • DEET is best available product; effect last for 4-6 hours. on application. 30
  31. 31. Personal Prophylaxis(contd) c. Screening- Screening of buildings with zinc, aluminum, plastic or bronze having 16 meshes to the inch is recommended. d. Protective clothing. d. Others- Mosquito hitting swatter, use of fan at high speed, repellents. 31
  32. 32. Personal Prophylaxis(contd) Insecticide Vaporizers • Protect against mosquito and biting flies by, 1. Irritating and disturbing them after contact and preventing them from biting and also preventing them entering room. 2. Paralyzing or killing them. • Coils, mats, liquid vaporizers and aerosols/spray- Transfluthrin, Legislative control • Use of laws to prevent / reduce propagation and spread of vectors is an effective means of vector management, through stringent approach. 32
  33. 33. •Intermittent irrigation •Water level management •Land filling •Channelling •Draining •Exotic natural enemies •Larvivorous fish •Microbial agents Source reduction Biological •Insect growth regulators •Adulticides •Larvicides Chemical IVC Health Education •Community •School education •TV •Mass media Personal Protection Bed nets and repellents 33
  34. 34. Key elements of an IVC Strategy 1. Advocacy, social mobilization and legislation – Promotion and inclusion of IVC principles. – Empowerment of communities for sustainability. – Establishment or strengthening - regulatory & legislative control for public health. 2. Collaboration within the health sector and other sectors: – Agriculture and agriculture development projects. – Urban sector; – Industrial development; – Infrastructure development projects; – Water resources development projects; – Housing projects; 34
  35. 35. 3. Integrated approach • IRS in high risk areas and in epidemic situations based on vector behavior and community acceptance. • Use of insecticide-treated nets/long-lasting insecticidal nets and other personal protection methods. • Environmental management. • Biological control. 4. Evidence-based decision making • IVC strategy requires assessment of the vector control needs based on the local factors. • Demands efficient surveillance/ information management system that highlights targets for vector control interventions. 35
  36. 36. 5. Operational and implementation research • Strong operational and implementation research support for development of new and modified tools 6. Capacity building • expertise at the central, as well as peripheral levels. • developing tools and guidelines in local languages and training of personnel for vector control. 7. Monitoring and evaluation • indicators as per the local requirements and targets set. • Inputs, costs & outcome of different interventions, when used singly or in combination & simultaneously or consecutively in a defined area, must be monitored. 36
  37. 37. Thank you 37