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

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

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:

1 Describe the epidemiological characteristics of dengue hemorrhagic fever in Binh Phuoc province for the period of 2008 - 2016

2 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, 5 boxes and 123 references including 57 foreign ones There are 3 page background, 30 pages Literature review, 21 pages Research methodology, 35 page research results, 31 pages discussion, 3 page conclusion and 3 page recommendations

CHAPTER 1 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 2 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

2 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:

2 2 1

2 2 2 1 1 1 2

/ 1

) (

) 1 ( ) 1 ( )

1 ( 2

p p

p p p p z p p z

n

−

− +

− +

−

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 3 RESEARCH RESULTS

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 2 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 4 years

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

Chart 3.3 Number of morbidity/ deaths from DHF per 100000 people for the

231 205 197

50 44 113

180 523

968

922 964

658 424 224 167 58.4 43.6 61.4 116.4

257.2 440.2

624.6 594.2

453.4 269.6 168.6 131

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 4 years However, the mortality rate tends to decrease

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

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

Bu Dang

Bu Dop

Bu Gia Map

Chon Thanh

Dong Phu

Hon Quan

Loc Ninh

Phuoc Long

Đong Xoai

269

332 344

369 339 297 209 138 91

64 58

37 670

Table 3.1 Index of households with Aedes aegypti, distributed monthly

Table 3.2 Index of water containers having Aedes larvae in 100 investigated

households, distributed monthly in the period 2008-2016

The Breteau index of months in the year 2008 was much higher than the average of 5 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

engue vec ctiveness

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Table 3.4.Collaborators’ activities to mobilize the community participation

during the implementation of the intervention

Commune

Phu Thinh Commune

Number of village health workers, hamlet women,

commune youth union, hamlet leader participating in the

DHF prevention program

11 4

Average number of households a collaborator must

Rate of signed commitments on DHF prevention between

Number of leaflets on DHF distributed (1 time / year x 2

Number of broadcasts on DHF (1 month / time x 2 years) 528 192

Number of meetings for propaganda (6 months / hamlet) 88 32

Number of posters of DHF hung in public areas 14 7

Activities of the intervention program on DHF prevention

Health education and communication programs aiming at: Improving people's knowledge and practice on early identification of DHF disease, changing their

wrong attitudes and opinions, changing risk behaviors on dengue prevention and control This program is implemented through target audience analysis to create media products In addition, the communication toolkit is designed based

on official letters, decisions and directives on the strengthening of DHF

prevention measures in Vietnam

Communication products

(1) Commitments: The commitment is signed by the household head, the

collaborator, the program supervisor and leader of the Commune People's Committee The commitment is to instruct villagers to carry out activities to eliminate larvae and prevent mosquito bites

(2) Leaflets: Leaflets were designed with two sides with specific

instructions, help people know how to prevent DHF, recognize the disease early

and guide how to handle Leaflets were distributed to each household

(3) Poster: large size posters are hang in crowded areas to attract people's

attentions The posters specifically guide the development cycle of vectors and

measures to eliminate mosquito larvae

3.2.2 Effectiveness of improving knowledge, attitudes and practices of the people

Table 3.5 Comparing the understanding of the causes of DHF

Content

Intervention group

(n=294)

Control group (n=287)

Intervention effectiveness (%) Before After p Before After p

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

Table 3.7 Comparison of knowledge about dengue disease awareness and

management

Hiểu biết đúng

Intervention group (n=294)

Control group

(%) Before After p Before After p

Table 3.8 Rate of people accepted or supported actions to protect water

resources from insects or larvae

Action

Intervention group (n=294)

Control group

(%) Before After p Before After p

Fish raising n 68 171 < 0.05 113 136

> 0.05 132

% 23.1 58.2 39.4 47.1 Water containers

rinsed and cleaned