i MINISTRY OF TRAINING AND EDUCATION MINISTRY OF HEALTH NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY * NGUYỄN LÂM THE EFFECTIVENESS OF COMMUNITY – BASED METHOD IN DENGUE VECTOR CONTROL AT CAI BE DISTRICT, TIEN GIANG PROVINCE, 2012-2013 Major: Public health No: 62720301 SUMMARY OF PHD THESIS IN PUBLIC HEALTH Hanoi – 2015 ii STUDY WAS COMPLETED AT THE NATIONAL INSTITUTE OF HYGIENE AND EPIDEMIOLOGY The scientific guidace: Prof Dr Tran Ngoc Huu Prof Dr Nguyen Anh Dung Reviewer 1: ……………………………………… Reviewer 2: ……………………………………… Reviewer 3: ……………………………………… The thesis will be defended at the state thesis Council meeting at National Institute of Hygiene and Epidemiology, at hour ,day month year 2015 Thesis can be fond at: National Library Library of National Institute of Hygiene and Epidemiology INTRODUCTION Dengue hemorrhagic fever (DHF) is an acute mosquito-borne viral infectious disease and can cause of major outbreak Aedes aegypti is the main vector transmitted disease Dengue is found in tropical and subtropical climates worldwide The disease is now endemic in more than 100 countries in South-East Asia and Western Pacific regions Appropximately 40% of the world’s population live in areas where there is a risk of dengue transmission Each year, there are about 50 million dengue infections and around 500,000 individuals are hospitalized with DHF In Vietnam, DHF is local endemic and appears in rainy season Recently, each year, there are several hundred thousand infected cases and about hundred of those affected die As of now, there is unknown specific anti-viral medicine for dengue fever and no vaccine for dengue Finding effective vector control methods in order to restraint DHF has been challenging not only for Vietnam but also for the world While waiting for the development of a vacine, the only method to control or prevent the transmission dengue virus is to combat vector mosquitoes through the involment of community Tien Giang has the highest mortality rate of DHF in the Southern area In last few years, the disease prevention has been supported by the local government and organisations but why it hasn’t brought the high effect? Have vector control guidances met the actual local condition? How and what methods of the health education and communication for dengue vector prevention to encourage the community participation in an active and longterm effectiveness? While waiting for the effective solution of vacine as well as other biological methods in research and trial period and to solve the current urge problem of DHF prevetion in Tien Giang, we have conducted the research: “The effectiveness of community – based method in dengue vector control in Cai Be district, Tien Giang province, 2012-2013” There are two objectives of this research: The description of the knowledge, the attitude and the practice of the local people in the implementation of DHF control and prevention solutions and control the vector index in Cai Be district, Tien Giang province, 2012-2013 The assessment of the effectiveness of community – based vector control method in Cai Be district, Tien Giang province, 2012-2013 Scientific contributions and practical value: - The intervention program is totally based on community, community work and responsibility, community selected vector control methods, participation in planning and implementing The vector control activity covered all households in the intervention areas Simple and eassy applying vector control methods were used appropriately and effective in reducing the vector index in the community - Saving the cost of the vector control at the community was by using the vector control force as the leader of the household and students with the support and involment of the hightly respected public figures (self-management group and teachers) Each member above was considered as a collaborator of the national program and they controlled vector at their own households - While the current communication measurement in the DHF/DF vector control have to face with many challenges in applying to each local area, the community-based vector control in this research matched the demand and the current situation This research succeeded in mobilizing the community in practising the vector control, providing the scientific evidence in the effectiveness of the vector control This research also worked as the base to implement the intervention at the community The result of this research can be used in the evaluation research of the effectively implementing intervention in the DHF/DF prevention as well as in providing the baseline data for future studies THESIS STRUCTURE The thesis has 126 pages, 51 tables, 17 pictures and 11 appendixes In which: The introduction and objective parts take pages, the overview takes 33 pages, the method part takes 19 pages, the results part takes 34 pages, the discussion part takes 35 pages, the conclusion part takes page and the recommendation part takes page The thesis has 146 references that are included 103 Vietnamese and 43 English references Chapter OVERVIEW 1.1 Definition of Dengue hemorrhagic fever/ Dengue fever Dengue Hemoharrgic Fever (DHF) or Dengue Fever (DF) is an acute mosquito-borne disease caused by the dengue virus and can cause of major outbreak Dengue virus belongs to the family Flaviviridae; genus Flavivirus and four serotypes of the virus have been found Aedes aegypti is a primarily vector transmitted disease 1.2 Current situation of DHF/DF 1.2.1 Current global situtation of DHF/DF Dengue pandemic has occured in the sub-tropical and temperate climate areas, South-East Asia and Western Pacific regions are the most seriously affected According to the strategic plan of WHO from 2008 – 2015, there are about 1.8 billion (>70%) of the population at risk for dengue in South-East Asia region 1.2.2 Current situation of DHF/DF in Vietnam DHF/DF is a local endemic disease in Vietnam, one of 10 declared infectious diseases and has the highest infection and mortality rate The populations at risk of acquiring dengue viral infections in dengue circulation regions is around 70 million 1.2.3 Current situation of DHF/DF in Southern Vietnam The first recorded case was in the Melkong Delta, then spreaded into many epidemics with the cyle of 3-5 years In 1998, there were 123.997 cases and 347 cases of death In 2005, the dengue-infected case was at No.2 after the diarrhea in the list of 24 infectious diseases From 2006-2012, the incidence of infected cases was higher than the average of the cases from 2000-2005 In 2007, the infected rate/100.000 population was highest from 1999 but was less than 1998 In 2008, the rate of mortality/infection increased again (0.109%) The outbreak in 2010 had higher cases than in 2009 and the infection rate per 100.000 population increased 13.9% compared with the average of 2003-2007 From 20112013, the percentage of infection and death case decreased The rate of infected cases was 72 per 100,000 population in 2014 and decreased in comparison with the rate of 2013 and the average rate of 2006-2010 Dengue virus monitoring was carried out regularly and has found four co-circulating serotypes DEN-1 virus was predominant than other serotypes during years from 2006 – 2014 The number of insect in 2010 was higher than 2009 and the average of 2004-2008 The mosquito density in 2012 was in the range of 0.3-0.7 (mosquito/household) which was higher than 2011 and less than the average of 2007-2011 In 2013, the BI index was in the range of 28-50 and less than at the same time period of 2012 and remained unchanged in 2014 1.2.4 The situation of DHF/DF in Tien Giang Tien Giang continuously had the high rate of the dengue virus infection with the circulation of serotypes and the vector index changed with none specific regulation The BI index and the average of the Aedes condensity index were always at the high level among other Southern regions Currently, there has very small amount of budget or none for the cost of the DHF/DF disease prevention activity which has undertaken by local authorities, so the local authority also determined local people as a main force in the vector control activity However, the communication activity has limited, failed to meet the requirement in communication for changing behavior and failed to make the habit of the local people in the vector control practice through each household 1.3 The dengue vector physiology and ecology: 1.3.1 Aedes albopictus mosquitoes The adult Aedes albopictus has a fairy small size (about 3/16 inch) and almost similar with Aedes aegypti except for a white line along the back The physilogical ecology of Aedes albopictus is the same as Aedes albopictus 1.3.2 Aedes aegypti mosquitoes Aedes aegypti has an average size with the alternative black body with many white flakes Aedes aegypti stays horizontally The female mosquito sucks blood and lays eggs with the active time during the daytime and at the peak in the early morning and late afternoon The average life expectancy of the female mosquito is 30 days The female fertilizes times in a lifetime and each time with 58-78 eggs The life cycle has periods and during 10-15 days Aedes aegypti has distributed in tropical and temperate climate areas over all continents 1.4 The dengue vector surveillance and investigation 1.4.1 Monitoring adult mosquitoes The density index of Aedes mosquitoes is the average of the Aedes female number in an investigated household The index of the house with mosquitoes is a percentage of houses positive for adult female mosquitoes 1.4.2 Monitoring Aedes larva: There are frequently used index The house index (HI): percentage of houses positive for Aedes larvae The container index (CI): percentage of all containers with water that are Aede larva/pupa positive Breteau Index (BI): number of Aedes positive containers per 100 houses The larval density : The average number of Aedes larva in an investigated household 1.5 Method and model of vector prevention The research of antiviral vaccine against Dengue virus has been developing and going into clinical trials In Vietnam, the DHF/DF preventive strategy is included the pilot colaborator model in 10% of the commune and province; the activity of the colaborator has reduced the vector index but not reached the requirement The research of controling epidemic result showed that the effectiveness in limiting the spread of diseases of epidemic potential Some reseachers have found several intergrated models in vector control by using biological agents as Mesocyclops or larvivorous fishes 1.6 Some terms in the research The water container: All containers such as large or small, which contain water even the miscellaneous stuffs and stagnent wastewater container Miscellaneous stuffs: The vase, waster bowl against ants, water bowls for cattles The waste: All the discarded items outside the house such as coconut shell, tires, cans, barrels, buckets, jars, jars broken Containers with lids: all water containers have the lid, so mosquitoes are inaccessible breeding Water containers with larvae: water containers have Aedes aegypti and Aedes albopictus larva inside The percentage of water containers with larvae: The percentage of water containers with larvae inside per total number of similar water containers Larvae source: Any individual or category water containers with large numbers of Aedes larvae that create a large number of Aedes adults Household: A group of people that is living in a same house, eating together and sleep in the same house Indoor and surrounding areas: The indoor house is an area inside of the house with the roof against rainwater The other remaining part of the house is called surrounding area Household without larvae: A household has none Aedes larvae in any water containers Community: is a social unit with the structure A group of people shares and are bound by common characteristics and values which are set through the interaction and communication of the member Community-driven development (CDD) or Community-based activity is a development initiative that provides control of the development process, resources and decision making authority directly to community groups Chapter METHODOLOGY 2.1 Objective Quantitative research: Householder / representatives, students and secondary school teachers, group leaders / mass organizations and DHF vector Qualitative research: Vice director and DHF/DF responsible staffs of the Health Prevetive Center, the official of Secondary of Education and Training Agency, the leader of the People Committee and the Commune Health Center, head/deputy of People's Committee, leaders of mass organizations, the principal of the secondary school, head teachers and class presidents 2.2 The study location and time The research was conducted at Cai Be district, Tien Giang province This research was operated from May 2012 until Feb 2014: The period of assessing the current situation before the intervention from May to Oct 2012; Applying the intervention from Oct 2012 to Oct 2013; Investigating the effectiveness of the intervention from Oct 2013 – Feb 2014 2.3 Study design Cross-sectional study described the situation before the intervention, community intervention with case control group Cross-sectional study analyzed the situation after the intervention, the before and after studies and the quantitative and qualitative studies 2.4 Sample size and sampling method 2.4.1 Quantitative research The communes were chosen by Using purposeful sampling, in which: control communes and intervention communes The calculating formula for estimating the sample size with proportions in the population: n: the minimum sample size of each group; α, β = 0,01: level of significance; Z α/β = 1,96 95% confidance interval; Z 1- = 99%: Force sample The estimate after the intervention has the household without Aedes larvae in the intervention group p1= 85% and the control group p255% Sample size n = 107 (the largest sample size) Because of selecting cluster group sample to increase the accuracy, the sample size will be multiplied with the DEFF = (the design effect) and 5% of reserve samples Sample size after rouded up was 340 Sample size of the head of household participated in study was 340 by selecting probability cluster sampling method The selected cluster was equal the hamlet of the commune The identified sampling interval k was the number of the house per the number of cluster Selecting the first household of each cluster was by choosing randomly Choosing the next household until reaching the required sample size in each cluster was based on the coefficient k Making the list of selected households in each investigated cluster was by following the route, the hamlet and selfmanagement group Sample size of student participated in study was 340: by selecting probability cluster sampling method as selecting the household, the number of the cluster was equal the number of the class Selecting the first student in the cluster was by choosing randomly Sample size of the teacher, the leader of the self-management group: the sample size for investigation was 100 teachers and 150 leaders Using the totally sampling method, 100% teachers and 100% leaders 2.4.2 Quanlitavtive research Purposeful sampling method: Depth interview: A vice director in charge of professional job and a responsible person in DHF/DF of the Health Prevention Center in district; a responsible person in charge of the secondary school in the education and training department; two CPC leaders; two principal teacher of the secondary school and two leaders of the CHS in two intervention communes Group discussion: two discussions with the representative of hamlet and self-management group, there were 12 chosen people in each group interview Two interviews with the group of the head teacher, there were 10 selected people in each group interview There were interviews with the class president and 15 selected students were chosen in each interview The workshop with stakeholders to identify priority measures in the DHF/DF vector control had 40 people attending 2.5 The variable and evaluation index 2.5.1 The variable index Including the information of the objective, knowledge, attitude and practice in the DHF/DF prevetion 2.5.2 The evaluation index The proportion of the sex, the education level and occupation, the proportion of the receiving information source, the rate of having good knowledge, attitude and practice in the DHF/DF prevention The house index (HI) with having Aedes larvae, the CI with existed Aedes larvae, the BI, the HI with existed Aedes adult 2.6 The implement and skill for collecting information 2.6.1 The implement for collecting information 11 Table 3.23 Protection of water containers before intervention Control Intervened Difference Commune Commune (%) Water containers (n=930) (n=930) Freq (%) Freq (%) Active/Used water containers 1498 100 1520 100 1,47 Covered with lid 295 19,69 312 20,53 4,27 Fish raising 134 8,95 137 9,01 0,67 Unprotected container 541 36,11 531 34,93 -3,27 Aedes larvae detected 528 35,25 540 35,53 0,79 Sundry and abandoned containers detected Aedes 1144 100 1341 100 17,22 larvae Active/Used water containers 450 39,3 454 33,9 -13,74 The percentage of active water containers and containers with fish in control group were 20.53% and 9.01% respectively, while the percentages were 19.69% and 8.95% among intervened households The percentage of active water containers in intervened group detected Aedes larvae was 35.53%, 33.9% of abandoned water containers detected larvae while the percentages of control group are 35.25% and 39.3% respectively 3.2 Effectiveness of vector control intervention 3.2.1 Results of vector surveillance after the intervention The average number of Aedes larvae per household before the intervention (August 2012) was 32.47 (larvaes/household), and 3.39 (larvaes/household) after the intervention (August 2013), equivalent to a decrease of 89.56% The percentage of water containers containing Aedes larvae decreased from 35.54% to 11.83% (66.71% decrease equivalent) The curve shows that DI and BI of intervened group decreased significantly in comparision with the control group 12 BI-Intervened commune BI-Control commune DI-Intervened commune DI-Control commune Figure 3.1 Breteau Index and DI between 9/2012 and 12/2013 3.2.2 Information sources and acceptability Table 3.25-3.26 Information sources and acceptability Control Intervened Commune commune Information source p p*** (n=930) (n=930) Before After Before After TV 78,9 87,5 0,028 77,8 89,7 0,017 Commune’s radio 36,3 39,1 0,088 36,1 47,3 0,002 Books, newspaper 11,8 11,3 0,768 12,4 13,1 0,445 Picture, leaflet, poster 25,3 30,4 0,022 27,3 34,9 0,003 Teacher 18,2 18,8 0,473 19,2 37,7 0,001 Medical staff 36,7 40,1 0,511 39,5 43,5 0,038 Self-management 20,2 21,4 0,254 23,5 39,7 0,032 group/MOs Used to know 88,7 89,9 1,35 89,6 100 χ test, p: pre-post comparison in control group; p***: in intervened group After the implementation of intervention program, there was an increase in the information sources (p0.05) Information acceptability increased 11.61% in comparison with before the intervention The effectiveness of intervention in intervened group was 10.25% higher than it was in control group 13 3.2.3 The improvement of knowledge regarding disease prevention Table 3.33 Knowledge of participants on DHF prevention and control Control Intervened Intervention commune EI commune EI Knowledge efficiency (%) (%) (n=930) (n=930) (%) Before After Trước sau Correct 56,3 61,6 57,1 94,1 9,41 64,8 55,38 Incorrect 43,7 38,4 42,9 5,9 Test χ2=5,616; p=0,092 χ2= 11,177; p=0,001 3.2.3 The improvement of knowledge regarding disease prevention There was an increase in the percentage of participants with correct knowledge on DHF prevention and control by 64.8% in comparison with before the intervention, from 57.1% to 94.1% (p0.05) Table 3.34 Changes in average score of knowledge after the intervention Control Intervened Differ Differ Intervention Average commune commune ence ence Efficiency score (n=930) (n=930) (%) (%) (%) Before After Trước Sau Correct 34,91 35,65 35,22 44,12 2,12 25,27 23,15 knowledge + 5,54 + 6,21 + 5,04 + 6,25 CI 95% CI 95% Paired t-test (35,14-36,16), p>0,05 (43,71-44,54), p0,05 (15,15-15,30), p0.05) Although it is not statistically significant, the primary results reveal the variety between two groups, however, the efficiency indicator (EI) should be included in postintervention analysis that compares between intervened group and control group to prove the effectiveness caused by the intervention The number of water containers in intervened group and control group were 2.642 and 2.861 respectively Among the water containers of intervened communes, 978 ones were detected with Aedes larvae while it was 994 containers in control group The number of larvae detected 20 containers in intervened group was 1.64% higher than in control group The Breteau Index (BI=107) of intervened group was 1.9% higher than the control group However, the indicator of Aedes larvae detected water containers of intervened group (CI=34.7%) was 6.22% higher than in the control group (37.0%) The vector indicator of this study was fairly higher than other researches that were conducted in the South Concerning the active water containers, the percentage of lid covered containers in intervened group (20.5%) was higher than in control group (19.7%), equivalent to 4.06% of difference The active containers, which contained fish, only accounted for 9% (similar in two groups) Unprotected containers were reported with 3.32% of difference between two groups (34.9% and 36.1% for intervened and control group, respectively) Aedes larvae detected water containers made up 35.5% of households that was similar to control group There was a remarkable decrease in the percentage of sundry and abandoned containers that were infested with Aedes larvae (decrease by 71.37%) while the decrease in control group was only 13.74% Aedes larvae detected household index shows that 62.4% of intervened households were detected with larvae that was 1.27% lower than in control group (63.2%) Aedes mosquito detected household index was 57.6% that was 11.63% higher than control group (51.6%) 4.2 The improvement in vector control activity The percentage of people with correct knowledge on DHF prevention and control increased 64.8% after the intervention (p0.05) The percentage of people with correct knowledge in this study is higher than a study in Dong Thap (2006, 50%) and a study in Can Tho (207, 85%) The intervention indicator is also higher than in a study in Bac Lieu Communication intervention through health collaborators and school is in conducive to 15.8% of the increase in correct knowledge The intervention contributed to the change in attitude in DHF prevention and control, after the intervention, the percentage of correct attitude increased 44.17% (p[...]... Ngoc Huu, Nguyen Anh Dung (2013) “Vector control of dengue hermorrhagic fever in school, Tien Giang Province, 2012- 2014”, Journal of Prevetive Medicine, Volume XXIII, No 10 (146), page 132135 2 Nguyen Lam, Do Nguyen Thuy Nhi, Tran Ngoc Huu, Nguyen Anh Dung (2014), “Vector control of dengue hermorrhagic fever based on selfmanagenement group model in Cai Be district, Tien Giang, 2012- 1013”, Journal of Prevetive... between case and control groups The percentage of correct knowledge, attitude and practices regarding dengue prevention in intervened group were 57.1%, 64.3% and 32.9%, respectively While the percentage in control group were 56.3%, 60.5% and 35.7%, respectively (p>0.05) Table 3.22 Vector indicators of Dengue fever Control Intervened Difference commune Commune (%) Indicators (n=930) (n=930) Number of... intervention 3.2.1 Results of vector surveillance after the intervention The average number of Aedes larvae per household before the intervention (August 2012) was 32.47 (larvaes/household), and 3.39 (larvaes/household) after the intervention (August 2013) , equivalent to a decrease of 89.56% The percentage of water containers containing Aedes larvae decreased from 35.54% to 11.83% (66.71% decrease equivalent)... group decreased significantly in comparision with the control group 12 BI-Intervened commune BI-Control commune DI-Intervened commune DI-Control commune Figure 3.1 Breteau Index and DI between 9 /2012 and 12 /2013 3.2.2 Information sources and acceptability Table 3.25-3.26 Information sources and acceptability Control Intervened Commune commune Information source p p*** (n=930) (n=930) Before After Before... proved by the ethics council of National Institute of Hygiene and Epidemiology 10 Chapter 3 STUDY RESULTS 3.1 Knowledge, Attitude and Practice regarding Dengue prevention and vector indicators Table 3.21 Knowledge, Attitude and Practices regarding dengue prevention Control Intervened Knowledge, commune (n=930) Commune (n=930) p* Attitude and Practices Freq (%) Freq (%) Correct knowledge 524 56,3 531 ... of Dengue hemorrhagic fever/ Dengue fever Dengue Hemoharrgic Fever (DHF) or Dengue Fever (DF) is an acute mosquito-borne disease caused by the dengue virus and can cause of major outbreak Dengue. .. district, Tien Giang province, 2012- 2013 The assessment of the effectiveness of community – based vector control method in Cai Be district, Tien Giang province, 2012- 2013 Scientific contributions... prevetion in Tien Giang, we have conducted the research: “The effectiveness of community – based method in dengue vector control in Cai Be district, Tien Giang province, 2012- 2013 2 There are