Một số đặc điểm dịch tễ học bệnh sốt xuất huyết dengue và hiệu quả mô hình giám sát chủ động vector truyền bệnh tại tỉnh bình phước tt tiếng anh

1 INTRODUCTION For decades, dengue has been one of the most infectious diseases in many countries and has spread to many parts of the world The disease occurs in the tropics and subtropics, in which Southeast Asia and the Western Pacific are the two places with the highest incidence It is estimated that there are about 390 million dengue hemorrhagic cases worldwide each year with 96 million people have serious clinical manifestations The world in general and Vietnam in particular are looking for effective measures to control dengue fever The radical solution is to reduce and eliminate mosquito breeding resources But after many years of implementing measures to prevent dengue, the dengue epidemic is still complicated In 1999, the National Program against Dengue Hemorrhagic Fever in Vietnam was established and put into operation with the goal of reducing death, reducing morbidity, preventing epidemics and socializing dengue fever prevention activities Binh Phuoc is one of the provinces in the Southeast where high prevalence of dengue fever Although the National Dengue Hemorrhagic Fever Project has been implemented throughout the districts, dengue fever often arises every year, sometimes arising and spread in some communes and wards After many years of implementing the project, due to budget constraints, the cooperative network only implemented in about 10% of the communes, prioritizing the selection of communes with high disease incidence, low educational level and economy, difficult to reach the mass media However, after 2013, dengue fever prevention activities have been integrated in the activities of the health centers Therefore, with the hypothesis that building a volunteer network in the community along with grassroots health will help replace the collaborator model for effective community-based dengue prevention, we conducted research on the subject: “Some epidemiological characteristics of dengue hemorrhagic fever and effectiveness of active surveillance model of vector transmission in Binh Phuoc province” with the following objectives: Describe the epidemiological characteristics of dengue hemorrhagic fever in Binh Phuoc province for the period of 2008 - 2016 Evaluate the effectiveness of the dengue viral vector surveillance model at the grassroots level for the period 2013-2016 NEW CONTRIBUTIONS OF THE DISSERTATION This study was the first to have a well-established scientific database on the epidemiological characteristics of dengue hemorrhagic fever in Binh Phuoc for the period 2008-2016, showing the cyclical nature of the epidemic At the same time, the study provides a model using grassroots health workers and volunteers to build a vector surveillance network, prevention and control of dengue fever in the community LAYOUT OF THE DISSERTATION The dissertation consists of 123 pages, 28 tables, 10 charts, boxes and 123 references including 57 foreign ones There are page background, 30 pages Literature review, 21 pages Research methodology, 35 page research results, 31 pages discussion, page conclusion and page recommendations CHAPTER LITERATURE REVIEW 1.1 History of Dengue virus detection and vectorization 1.1.1 Dengue hemorrhagic fever concept Dengue fever or Dengue hemorrhagic fever (DHF) is an acute Dengue virus infection that is transmitted by mosquitoes and can cause major epidemics 1.1.2 History of virus detection and vectorization In the years 1778 - 1780, the first recorded dengue epidemic occurred in Asia, Africa and North America After World War II, a dengue epidemic appeared in Southeast Asia and has since spread throughout the world Dengue virus is the main cause of dengue fever By 1906, Bancroft had demonstrated that the main vector was Aedes aegypti Recent studies in the Philippines, Indonesia, and the Western Pacific have demonstrated that Aedes albopictus, Aedes polyneiensis are also vectors that are involved in dengue transmission 1.2 Dengue hemorrhagic fever epidemiology Dengue has become an epidemic and is now circulating in more than 100 countries in tropical areas, Southeast Asia and the Western Pacific, Africa, and Africa with about 2.5 billion people living in epidemic risk areas Southeast Asia and the Western Pacific are the two most affected regions Dengue is one of the major public health burdens and is a major public health concern around the world The annual number of dengue cases is estimated at 50 million people, 500,000 cases of DHF are hospitalized each year, 90% of which are under 15 years old The average death rate is about 5% The number of dengue cases reported over the past 55 years has increased to 2,427 times The worst affected areas are Southeast Asia and the Western Pacific In particular, countries with high mortality and morbidity in recent years are Vietnam, Thailand, Indonesia, Malaysia, Philippines, Singapore, Laos, Cambodia In Vietnam, the first dengue epidemic occurred in the North in 1958, in the south in 1960 with the death of 60 pediatric diarrhea patients Before 1990, DHF occurred cyclically with an average duration of 3-4 years After 1990, the disease has continued with increasing intensity and scale From 1999 to 2003, the average number of cases was reduced to 36,826 cases and 66 deaths each year Peak season of DHF is from June to October every year Between 2001 and 2011, 76.9% of dengue cases and 83.3% of dengue deaths occurred in 20 southern provinces About 90% of deaths from DHF are below the age of 15 Currently, the population in the DHF area is estimated at 70 million people 1.3 Some measures to control transmission vector of dengue hemorrhagic fever 1.3.1 Chemical measure: Use insecticides, but currently the situation of Aedes mosquito resistance to chemicals is increasing, so sooner or later, chemical intervention will be ineffective 1.3.2 Biological measure Biological measures are mainly used to eliminate larvae, cut off the infectious cycle of diseases such as Mesocyclop, water bugs, dragonfly larvae, fungi, Wolbachia bacteria, by raising fish in water containers etc 1.3.3 Community model involved in dengue fever prevention Many studies of foreign authors have highly appreciated the model of community-based dengue prevention Community participation is integral to dengue prevention Social mobilization and behavior change communication have brought many benefits to the dengue prevention program such as reducing the frequency of dengue transmission in epidemics, helping health facilities not to be overloaded by too many infected cases at the same time; reducing dengue virus infection multiple times; The community plays a crucial role in rapid action when outbreaks occur and at the same time, improve the environmental health conditions In Vietnam, since 1999, the national dengue fever prevention and control project has been established and operated nationwide with the goal of reducing the morbidity and morbidity of dengue The project's main strategy is to control community-based larvae In order to implement this strategy, the project focused on communication education in both direct and indirect forms Indirect communication is carried out through mass media such as radio, television, newspapers, pictures etc In this way, the project provides the community with the most basic knowledge about Prevention of dengue fever, with the ultimate desire is that people themselves change their attitudes and behaviors properly in dengue prevention However, changing the behavior of people is a very complex matter Therefore, in addition to the indirect communication, the dengue fever prevention and control project has piloted the method of direct communication in the community, monitored with the support of local authorities In order to effectively implement the project, governments and health authorities at all levels work out action plans to take appropriate measures to eliminate the source of the transmission vector at home Collaborators will be the intermediary in communicating the plans, methods and basic knowledge on dengue fever control and at the same time help people implement necessary measures to eliminate the larvae However, the resources of the project are insufficient to cover the entirety of the project but only in the pilot communes which account for about 10% of communes and wards 1.4 Research on the effectiveness of community-based dengue prevention activities through collaborative activities Assessing the effectiveness of collaborators is a complex task that involves many aspects: from the input, the operation process, to the outputs Changes in people's knowledge, attitudes and behaviors, and the increase in the number of households without larvae are the most direct, recognizable, and most visible manifestations Most of the studies focused only on investigating the improvement of insect indices through household surveys before, during, and after the intervention, without surveying the behavior of the people Other studies are concerned only with the behavior of people before, during and after intervention, with little attention to insect indices CHAPTER SUBJECTS AND METHODOLOGY 2.1 Research subjects * Phase1: study the epidemiological characteristics: - Patients with dengue fever - Transmission vectors * Phase 2: community intervention study: - Volunteers are participating in the monitoring team for dengue control in intervention communes - Heads of household s or representatives - Water containers and household waste - Transmission vectors: mosquitoes, larvae 2.2 Research methodology 2.2.1 Study Design: M ixed method study combining quantitative and qualitative research 2.2.1.1 Cross-sectional descriptive study: Evaluate the epidemiological characteristics of dengue in Binh Phuoc for the period 2008 - 2016 2.2.1.2 Community-based interventions with before and after assessment and comparison with the control group The main intervention in the study was the establishment of an insect screening network at the grassroots level in two communes without collaborators of the dengue prevention program Commune health workers are trained to monitor the insect indices in the commune every month Volunteers have been trained in basic knowledge on dengue communication, larval control and treatment methods in the villages Every month, volunteers visit each household, communicate the knowledge about dengue, help people understand the main agent to spread the disease and guide people to remove the larvae inside and outside their houses 2.2.2 Sample selection and sample size - Sample size for epidemiological study: Select the entire sample - Sample size for intervention study: Use the formula for calculating the sample size: {z n= 1−α / } 2p(1− p) + z1−β p1(1− p1) + p2 (1− p2) ( p1 − p2)2 The sample size was 276, in fact, there were 294 participants after intervention and 287 participants in the control group were eligible for inclusion in the data analysis 2.2.3 Techniques used in the study: interviews, group discussions, mosquito larvae monitoring, adult mosquitoes, dengue diagnostic tests 2.3.4 Data processing: Data were analyzed using SPSS 16.0 software and statistical tests in biomedical research CHAPTER RESEARCH RESULTS 20 6000 5237 18 5000 4000 16 3521 3470 2881 3000 2008 2009 1415 1000 1895 630 2010 2011 Number of morbidity 12 10 2346 2099 2000 14 2012 2013 2014 2015 2016 Number of deaths Chart 3.1 Number of morbidity/ deaths from DHF in the period 2008-2016 Chart 3.1 shows that DHF is regularly detected in Binh Phuoc province with the number of cases fluctuates over the years In 2008, the number of morbidity was 3521 patients, then tended to decrease markedly in 2009 and then increased and decreased slightly in the next years The epidemic was in 2012 with over 5000 cases but then the number of cases fell sharply and the lowest was in 2014 and then tends to increase in the years of 2015 and 2016 Thus, the chart has shown an evident trend of the epidemic cycle in every years 1200 1000 968 964 954 922 800 600 658 624.6 662 594.2 523 453 453.4 424 440.2 423 400 200 58.4 50 28 25 113 61.4 23 14 44 43.6 26 10 2008 257.2 198 180 124 116.4 57 29 17 2012 113 TB (08'‐12') 213 176 287 269.6 231 227 224 205 168.6 10 2015 11 244 197 167 131 12 2016 Chart 3.2 Number of dengue cases from 2008 to 2015 by the months of the year Chart 3.2 shows that patients with DHF occur throughout the year from January to December Dengue epidemic starts in May and large outbreaks occur from June to August and then gradually reduce In 2008 and 2012, the incidence of DHF in Binh Phuoc province was higher than the average for 2008-2012 573.8 600 3.5 500 412.9 367.8 400 322.5 300 259.1 239.2 2.5 205.6 1.5 200 149.8 0.7 0.4 100 0.1 0.5 0.2 0.2 67.6 0.2 0.3 2013 2014 2015 0 0.5 2008 2009 2010 2011 2012 2016 Number of morbidity/100000 people Chart 3.3 Number of morbidity/ deaths from DHF per 100000 people for the period 2008-2016 The results of Chart 3.3 show that the incidence of dengue hemorrhagic fever per 100,000 people in the years of 2008, 2012 and 2016 was the highest Thus, according to the population structure, the trend of epidemic cycle is still every years However, the mortality rate tends to decrease 665.5 700 600 500 477.7 437.5 400 359.6 315.9 300 266.6 202.6 200 129.6 97.6 124.5 100 Binh Bu Long Dang Bu Bu Gia Chon Dong Hon Loc Phuoc Đong Dop Map Thanh Phu Quan Ninh Long Xoai Chart 3.4 Average number of morbidity/100,000 people by living area It is clear in Chart 3.4 that the average number of cases per 100,000 people is highest in Chon Thanh (665.5), then Dong Xoai (477.7), Hon Quan (437.5), Dong Phu (359.6) ) Bu Dang has the lowest average number of cases in the province 400 332 300 269 344 369 339 297 209 200 138 91 100 64 58 37 67 ≤5 ->10 11->15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55 56-60 >60 Chart 3.5 Average number of DHF cases by age group Chart 3.5 shows the number of cases with dengue hemorrhage fever occurring most in the 16-20-year-old group, followed by the groups aged 11-15, 21-25, 25-30, 5-10 The group of 5-year olds had 269 cases per year, on average The incidence of DHF in the group of 30 years old and over gradually decreased Table 3.1 Index of households with Aedes aegypti, distributed monthly Months 01 02 03 04 05 06 07 2008 28 30 32 38 50 56 60 2009 12 16 20 40 40 20 12 2010 12 12 36 36 16 20 2011 21 25 34 30 33 61.5 42 2012 17.5 17.5 17.5 33 55 23.5 43 Average 18.1 20.1 27.9 35.4 37.2 35.4 35.4 08’-12’ 2013 20 20 23 35 43.5 40 25 2014 17.5 17.5 17.5 30 34 25 33 2015 8.5 10 23 33 28.5 20 2016 6.67 10 6.7 26.7 33.3 40 30 Years 08 09 10 11 12 54 32 44 36 36 44 36 40 20 10 50 26 42 34 26 38 22 22 36 31 25 33.5 16.5 33.5 10 42.2 29.9 32.9 31.9 22.6 21.5 13.4 11.5 11.5 23.5 30 22 32 25 20 28 33.5 27 23 11.5 30 56.7 33.3 33.3 23.3 Table 3.3 shows the index of households with larvae found highest in the years of 2008, 2009, 2011 and 2016 In these years, larvae indexes in most months were higher compared to the average of years from 2008 to 2012 In the rainy season, this index increased quite high compared to in the dry season Table 3.2 Index of water containers having Aedes larvae in 100 investigated households, distributed monthly in the period 2008-2016 Years 01 02 03 04 28 30 38 42 24 28 30 50 20 16 46 48 22.5 29 25 39.5 30 37.5 31.5 78 05 92 30 10 51 75 Months 06 07 102 104 24 24 30 40 99 128 23.5 70 08 94 84 120 38 43 09 78 50 50 32 41.5 10 72 46 44 28 20 11 62 36 38 50 43 2008 2009 2010 2011 2012 Average 24.9 28.1 34.1 51.5 51.6 55.7 73.2 75.8 50.3 42 45.8 08’-12’ 2013 25 20 33.5 40 46.5 58 25 28 16.5 11.5 11.5 2014 17.5 15 20 31.5 22.5 28 38 35 26.5 45 36.5 2015 8.5 11.5 23.5 36.5 36.5 20 30 43.5 33.5 25 2016 10 10 27 47 53 40 43 123 47 57 12 62 30 34 35 10 34.2 23.5 25 11.5 27 10 The Breteau index of months in the year 2008 was much higher than the average of years (2008-2012) In the years of 2010, 2011 and 2016, peaks of BI index in the rainy season were higher than the average Table 3.3 Index of households with Aedesaegypti mosquito, distributed monthly Months Years 01 02 03 04 2008 10 10 2009 10 13.3 13.3 16 24 10 10 2010 10 6.7 20 6.7 10 13.3 35 13.3 23.3 20 2011 13.5 17.5 21.5 23 2012 13.5 13.5 22.5 20 Average 08’-12’ 2013 30 06 07 08 09 10 11 12 36.7 43.3 53.3 43.3 33.3 26.7 26.7 36.7 26.7 23.3 30 32.5 33.5 23.3 36.5 16.5 20 15 16.7 13.3 15 10 13.3 10 6.7 16.5 11.5 23.5 13.5 30 15 11.4 12.2 18.12 20.46 26.44 21.14 24.02 31.66 25.04 19.98 17.64 13.74 12 9.985 21.5 29.95 2014 13.5 30 2015 13.5 2016 05 33.5 22 22 21.5 21.5 25 11.5 20 16.5 31.5 31.5 17 33.5 20 20 23.3 36.67 35 6.67 6.67 3.33 26.67 30 30 33.3 16.5 16.5 20 15 30 22 15 21.5 11.5 30 15 16.67 16.67 Table 3.7 shows that from 2008 to 2016, the index of households with Aedes aegypti mosquito have always been quite high and are in danger signs of epidemics in each month, the peak of epidemic outbreaks is from April and May to September and October every year Compared with the five-year average (2008 - 2012), in the years of 2008, 2011 and 2016, the number of households with Aedes aegypti mosquitoes increased in the rainy season Particularly, there were two peaks in August and September 2008 and September 2016, with the number of mosquitoes rising by about 40% to nearly 60% of the surveyed houses 14 Results from Table 3.15 show that the sources of information that people were provided about dengue before our intervention are mainly from television After intervention, the information on DHF that people were provided from photographs, loudspeakers, health workers and from local organizations and unions organizations increased in the group of intervention The difference with p 0.05 43 > 0.05 90.3 < 0.05 103 The results of Table 3.16 also show that, after intervention, people have better understanding of the signs of DHF disease (p 0.05 < 0.05 % 23.1 58.2 39.4 47.1 n 212 283 264 278 > 0.05 < 0.05 % 72.1 96.3 92.0 96.9 n 216 279 % 73.5 94.9 < 0.05 268 277 93.4 96.5 > 0.05 HQCT (%) 132 28 25.8 15 n 221 282 261 278 Keep water > 0.05 21.0 < 0.05 containers closed % 75.2 95.9 90.9 96.9 n 194 288 260 278 Cleaning water > 0.05 41.6 0.05 86.8 < 0.05 % 41.8 87.8 74.2 91.3 n 106 222 210 240 Check larvae > 0.05 97.9 < 0.05 weekly % 36.1 76.5 73.2 83.6 Table 3.21 shows that after intervention more than 80% of the study subjects had larvae tested, 76.5% checked larvae in their water containers weekly Intervention effectiveness was 86.8% and 97.9%, respectively Table 3.10 Practice of the study subjects on killing larvae and mosquitoes Content Destroy the container Use mosquito incense Use mosquito spray Use mosquito rackets or lamps n % n % n % n % Intervention group Control group HQCT (n=294) (n=287) (%) Before After p Before After p 110 260 231 272 > 0.05 118.6 < 0.05 37.4 88.4 80.5 94.8 103 129 96 115 > 0.05 > 0.05 5.4 35.0 43.9 33.5 40.1 97 114 109 120 > 0.05 > 0.05 7.5 33.0 38.8 38.0 41.8 21 24 21 27 > 0.05 > 0.05 13.7 7.1 8.2 7.3 9.4 Table 3.22 shows that after intervention, the larvae killing and controlling practice of the study subjects was better than before intervention (p 0.05 2013 14 84.6 20 82.0 >0.05 2014 24.2 36.9