Improving Awareness and Transmission Risk Reduction Related To Japanese Encephalitis in Ayeyarwady Region of Myanmar

Mya MM, Win AYN, Kyaw PP, Thaung S, Oo PM, Lin Z, Oo T, Wai KT and Thant K

Published on: 2023-06-02

Abstract

The selection is based on the 2012-2017 data of JE cases reported. Ayeyawady Regions was selected. From the Ayeyawady Region, Pantanaw Township that reported JE cases was selected purposively followed by random selection of Kyontonekalay and Kyonthet RHC. From Kyontonekalay RHC, Kyontonekalay and Pathew villages and from Kyonthet RHC, Aque and Kyonthet villages were selected. Kyontonekalay and Kyonthet villages have high density of pig farms, and Pathew and Aque villages have low density of pig farms. Therefore, this study covered two RHC four villages. For entomological surveys, breeding sites and vector density were sought in all four selected villages. Mosquitoes were collected from fixed mosquito catching stations of both field areas using Kanda net (K net) for animal bait, Indoor, outdoor and pig farms catches using light trap catches methods for 4 days during the study periods in each study site. Mosquitoes were caught with WHO sucking tubes from 18:00 to 06:00 hours of the next day. For identification of breeding sites larval surveys were conducted in and around two kilo-meters from the study villages. Collected adult mosquitoes and adult emerged from larva survey were identified by species according to different identification keys. Map out the location of vector breeding site, pig farming site and human settlement areas in the study villages will be recorded using GPS device. Result revealed that main JE vector, Culex tritaeniorhynchus adult and larvae were abundantly collected in both polluted water pools and rice fields in all selected villages. Other species Cx. vishnui, Cx. quinquefasciatus , Mansonia species and some Anopheles species were collected in water pools and polluted creeks and these species of adult mosquitoes were collected in high number by cattle bate and in pig farms collection . High number of pig farms and JE vector Culex tritaeniorhynchus are available in all study areas. Old and new JE history was available in both Kyontonekalay and Kyonthet villages. Therefore the study recommended that VBDC need to distribute LLIN nets and health education to all family members in the villages to protect JE transmission.

Keywords

Japanese encephalitis; Pig farm; Culex tritaeniorhynchus; Vectors; Epidemic

Introduction

Japanese encephalitis (JE) is the zoonotic disease caused by a JE virus (JEV) which is a mosquito-borne flavivirus spread to human through the bite of Culex mosquitoes. Culex tritaeniorhynchus is the primary vector. The virus cycles between amplifier hosts such as pigs and wading birds and Human [1]. Most of JEV in human is asymptomatic as less than 1% of infected people develop symptoms and incubation period is 5-15 days. Illness usually begins with acute fever followed by focal neurological deficits. Case fatality rate is approximately 20-30% and among survivors, 30-50 % has serious neurologic or psychiatric sequanlae [2]. To date, threats to JE outbreaks are mostly found in 27 countries in Asia and the Pacific Region in temperate and tropical regions including Myanmar. Since 1974, Myanmar reported its first outbreak of JE and in 2014, there was an outbreak in 46 villages of nine townships of Rakhine State coupled with lack of awareness of JE transmission and prevention among the villagers [3,4]. As JE is endemic in many parts of Myanmar, the existence of source, vectors and seed virus outbreak can occur at any time. Cases reported were slightly higher in rural population than in urban population. Simultaneously, VBDC implements awareness raising activities to improve alertness but limited. As of August 2017, data from Department of Public Health indicated a total of 491 JE cases occurred in the whole country especially from Yangon, Bago, Tanintharyi and Ayeyawady Regions and Kayin, Rakhine and Shan States [5]. In Dawpon Township, Yangon Region JE virus infection was detected in 52.1% of pigs. The known JEV vector mosquito species, especially Culex tritaeniorhynchus, were found in the study area but no concurrent human JEV infections were elicited [6]. In Myanmar, isolate of virus from pigs in DikeOo pig farm was done by PCR in 2009 and the isolate was identified as genotype III [7]. Japanese encephalitis virus isolated in C6/36 mosquito cells, identified by Immunofluorescent assay and reverse Transcriptase-Polymerase Chain Reaction, and then sequenced by DNA sequencer using pig blood sample from Thakayta Township. The Isolate was found Genotype 1[8]. An investigation on JEV infection in Bogalay Township Myanmar was done in 1999. Findings showed that JEV antibodies were detected in 33% of the pigs. They also found the Culex vector mosquitoes especially Culex vishnui followed by Culex tritaeniorhynchus. JE virus antibodies were not detected among the villages during the study [9]. There were reported cases in Kachin State, Myanmar in 2013. The spread of the virus in Australia is of particular concern to Australian health officials due to the unplanned introduction of Culex gelidus, a potential vector of the virus, from Asia. However, the current presence on mainland Australia is minimal. There had been 116 deaths reported in Odisha's backward Malkangiri district of India in 2016. The most important vector is Culex tritaeniorhynchus, which feeds on cattle in preference to humans. Japanese Encephalitis virus isolation has been made from a variety of mosquito species such as Culicine mosquitoes mainly Culex vishnui group (Culex tritaeniorhynchus, Culex vishnui and Culex pseudovishnui) are the chief vectors of JE in different parts of India [10]. Out of four major strategies for JE prevention and control (health education, vector control, immunization of people and pigs and epidemic preparedness and response) guided by World Health Organization, Southeast Asia Regional Office (SEARO/WHO), Myanmar is going to add JE vaccination in national immunization program for children starting from September 2017. However, community has poor understanding about the interplay of human health, animal health, changing agricultural practices, environment and socio-economic factors, and health care infrastructure. There is a need to focus disease prevention by mitigating the transmission risk through improvement of the awareness raising programs and risk reduction actions by incorporating one health concept in rural areas of vulnerable sites in Myanmar. Therefore the study planned to determine the vector bionomics of Culex species and responsible for Japanese Encephalitis transmission in 4 villages of Pantanaw Township Ayeyawady Region.

Methodology

Study Design

A cross-sectional descriptive study design was done.

Study Population

Study population consisted pig farmers, veterinarians, village authorities, health staff from rural health centers, village volunteers and insect collectors.

Study Area and Study Period

Pantanaw Township, Ayeyawady Region was selected. The selection is based on the 2017 data of JE cases reported. Pantanaw Township was found highest JE cases (20) reported. Therefore the study was conducted from Oct 2018 to March 2019.

Figure 1: Map of the study areas (Pantanaw Township, Ayeyawady Region).

 

Sample Size Determination and Sampling Procedure

The occurrence of JE vectors and it breeding sites and density were measured in four villages of Pantanaw Township, Ayeyawady Region. From the Ayeyawady Region, Pantanaw Township that reported 20 JE cases in 2017 was selected purposively followed by random selection of Kyontonekalay and Kyonthet RHCs. From Kyontonekalay RHC, Kyontonekalay and Pathew villages and from Kyonthet RHC Kyonthet and Aque villages were selected. Kyontonekalay and Kyonthet villages have high density of pig farms and Pathew and Aque villages had low density of pig farms. Therefore, this study covered two RHC and four villages.

Study Tools/ Data Collection Methods

For objective 1: Mosquitoes were collected from fixed mosquito catching stations between pig farm and human households of selected Kyontonekalay, Pathew, Kyonthet and Aque villages of both field areas of Kyontonekalay and Kyonthet RHCs using Kanda big mosquito nets (330 x 330 x 180 cm) (K-net) for animal bait and CDC light traps method was used for indoor and outdoor mosquitoes collection, Pig farms and cow shed collection in the selected areas of four villages. Animal bait big mosquito net, cow shed, Pig farms and light traps mosquito catching were conducted with WHO sucking tubes from 18:00 to 06:00 hours of the next day. All collected mosquitoes were kept in individual labeled paper cups.

Larva Collection

For identification of breeding sites, larval surveys was conducted in polluted water sources in and around three kilo-meters radius from the study site, such as brick kilns, ponds, paddy fields domestic wells, stream/creeks and all different types of water holding places, marshes around the irrigation ditches in paddy fields, hyacinth vegetation and water pools were examined for larvae by 3 Dips /water holding place with WHO dipper [11].

Susceptibility Test: susceptibility of Culex adult mosquitoes was done with WHO test kit.

Resting place: resting mosquitoes were searched in indoor and outdoor of the household, pig farms and cow shed.

The captured larvae and pupae were put in labeled plastic bags and brought back to the laboratory for species identification and colonization.

For Objective 2: Map of the location of Mosquito collection sites, vector breeding sites, pig farming sites and human settlement areas in the study villages were drawn by using Global Positioning System GPS device (GPSMap16 Garman, 18x-5HZ software interface application method by expert person.

Identification of Mosquitoes: Collected adult mosquitoes and adult emerged from larva survey were identified by species according to Peyton and Harrison [12-15].

Data Analysis

Data from various sources were triangulated for meaningful interpretation. Larval density was calculated by larvae/dip and percentage was computed for adult mosquito density per village by Excel software. Map of the study areas were drown by GPS device (GPSMap16 Garman, 18x-5HZ software interface application method by expert person

Results

Table 1. Prevalence of JE vector secondary vectors in selected areas of Pantanaw Township Ayeyawady Region.

                                                         Pantanaw Township Ayeyawady Region
Species Kyontonekalay RHC     Kyonthet RHC    
  Kyontonet % Pathew % Kyotnthet % Aque %
Cx.tritaeniorhynchus 185 20.04 256 30.22 460 32.08 156 24.61
Cx.quinquefasciatus 36 3.9 49 5.79 91 6.35 39 6.15
Cx.vishnui 227 24.59 120 14.17 263 18.34 67 10.57
Cx.gelidus 71 7.69 37 4.37 54 3.77 18 2.84
Cx.fuscocephala 14 1.52 22 2.6 28 1.95 16 2.52
Mansonia 67 7.26 58 6.85 162 11.3 68 10.73
Armigeris 40 4.33 28 3.31 38 2.65 22 3.47
An.minimus 1 0.11 0 0 2 0.14 0 0
An.vagus 75 8.13 39 4.6 60 4.18 66 10.41
An.maculatus 20 2.17 22 2.6 72 5.02 36 5.68
An.tessellatus 22 2.38 14 1.65 54 3.76 20 3.15
An.barbirostris 166 17.97 202 23.85 152 10.59 126 19.87
Total 924 100 847 100 1436 100 634 100

Result revealed that A total of 923, 847, 1434 and 634 mosquitoes were collected from Kyontonekalay, Pathew, Kyonthet and Aque villages of Pantanaw Township respectively in Ayeyawady Region. Of this main JE vector, Culex tritaeniorhynchus adult were found highest 460(32.08%) in Kyonthet village followed by 256(30.22%) Pathew village and lowest was found 185(20.04%) in Kyontonekalay village. Secondary JE vector of Cx. vishnui was found 227(24.59%) in Kyontonekalay village followed by 263(18.34%) in Kyonthet village the lowest was observed in 67(10.57%) in Aque village. Other species, Cx.quinquefasciatus, Cx.gelidus, Cx.fuscocephala, Mansonia and Armigeris species were collected 3.90 -6.35%, 2.84- 7.69%, 1.52 – 2.60%, 6.85 -11.30% and 2.65 -4.33% respectively in study areas. Anopheles species as An.minimus, An.vagus was found 4.18-10.41%, An.maculatus 21.17 -5.68%, An. tessellatus 1.65-3.77% and An. barbirostris 10.59- 23.85% respectively were collected in these studied villages.

Table 2. Different species of mosquito breeding sites in 4 villages in Pantanaw Township, Ayeyawady Region.


Sr. No. Type of water holding place Kyontone kalay Pathew Kyonthet Aque Total No. of larvae Mosquitoes species
Larvae Larvae Larvae Larvae
1 brick kilns 23 5 26 15 69 Cx. tritaeniorhynchus Cx. vishnui
Cx. quinquefasciatus
  Ponds 21 16 39 16 92 Cx. tritaeniorhynchus Cx. quinquefasciatus Cx. vishnui
An. maculatus
An. barbirostris
  rice fields 138 123 257 129 647 Cx. tritaeniorhynchus Cx. quinquefasciatus Cx. vishnui
An. minimus
An. barbirostris
An. vagus
  Slowly running water 15 27 38 15 95 Cx. quinquefasciatus
An.minimus
An.maculatus
  Stream 23 27 31 36 117 Cx. tritaeniorhynchus
Cx. vishnui
An. maculatus
 An. barbirostris
  Creeks 19 15 27 18 79 Cx.tritaeniorhynchus
Cx. vishnui
 An. barbirostris
An. vagus
  Foot print 11 5 18 9 43 An vagus,
Cx. tritaeniorhynchus
  Metal drums 44 52 36 47 179 Ae. aegypti
  Concrete tanks 16 13 15 11 55 Ae. aegypti
  Concrete Jars 36 41 82 49 208 Ae. aegypti
  Bago Jars 31 39 64 53 187 Ae. aegypti
Ae. albopictus
  Spirit bows 21 56 74 51 202 Ae. aegypti
Ae. albopictus
  Toilet water 18 6 21 9 54 Ae. aegypti Cx. vishnui, 
Cx.tritaeniorhynchus
  Marshes around irrigation ditches 34 22 34 38 128 Cx. tritaeniorhynchus Cx.quinquefasciatus Cx. vishnui
An. barbirostris
An. vagus
  Hyacinth vegetation 23 38 52 34 147 Cx.tritaeniorhynchus
Cx. vishnui
 An. barbirostris
An. vagus
An.maculatus
  Water pools 67 62 102 79 310 Cx.tritaeniorhynchus Cx. quinquefasciatus
Cx. vishnui 
An. maculatus
An. vagus, An. barbirostris
  Sand pools 7 4 8 2 21 An. tessellatus, An. minimus
  Total 540 547 916 609 2633  

Table 2. Shows that highest number of mosquitoes larvae were collected from rice fields water (647 larvae) followed by polluted stream (117 larvae) and lowest was collected in footprint (43 larvae). Culex tritaeniorhynchus and Cx. vishnui larvae were observed in all type of water holding places. Although in water storage containers as Metal drums, Concreted tanks, Concreted Jars, Bago Jars, and Sprite bows were observed mostly bred Aedes aegypti and Ae. albopictus but Cx.tritaeniorhynchus, Cx. vishnui and Aedes aegypti larvae were growing together in Toilet water containers as plastic buckets, Concrete jars, earthen pot and small Bago jars and small water holding concrete tank in Toilet.

Aedes aegypti and Aedes albopictus larvae were found positive in only household used domestic water storage containers in the studied villages. Cx. tritaeniorhynchus, Cx. vishnui, An.minimus, An. tessellatus, An. barbirostris, An. vagus and An. maculatus were collected from ponds, rice fields, stream, foot prints, sand pools, water pools, slowly running water and creeks of the Kyontonekalay, Pathew, Pyinmadaw canal and Kyonthet streams, Marshes around irrigation ditches, Hyacinth vegetation and non-polluted water pools.

Table 3: Source materials that JE information among community members.

Source of responds

Household members

(n=160) join structured interviews

Frequency

Percentage

JE transmission is occurred from pigs

90

56

transmission is occurred from cows/buffaloes

14

8.7

transmission is occurred from water birds

33

20.6

High risk among under 5 children

87

54.4

High risk those between age 5-15 years

55

34.4

High risk among pig farmers

26

16.3

Nearly 70% of respondents gave high priority to under five children for JE vaccination compared to between 5 to 15 years

72

45

A cross-sectional mixed-methods study design was used by conducting village surveys and focus group discussions in August 2018. Pantanaw Township was selected based upon 2012-2016 data of JE cases reported by the VBDC team, Ayeyawady Regional Public Health Department. Four villages under two RHCs were selected at random followed by random selection of 20 pig farmers and 20 householders without any pig farm was done from the list prepared by village authorities in each village, amounting to 160 join structured interviews. Basic health staff, veterinarians, voluntary health workers, administrative authorities, headmasters, and social organization members, amounting to 40 joined 4 FGDs. Community members cited JE transmission from pigs (90/160, 56%), from cows/buffaloes (14/160, 8.7%) and water birds (33/160, 20.6%). They recognized high risk among under 5 children (87/160, 54.4%), those between age 5-15 years (55/160, 34.4%) and pig farmers (26/160, 16.3%). Nearly 70% of respondents gave high priority to under five children for JE vaccination compared to between 5 to 15 years (72/160, 45%) that required attention. Qualitative strand further elucidated their opinions towards health talks at their villages by health staff in coordination with local authorities and to communicate at schools for sharing information to the teachers identified as the best channel to reach the community. Focus group discussants revealed popular measures to prevent mosquito bites. Findings highlighted the issues not only to improve awareness of JE in the community but also to reduce transmission risk and fill knowledge gaps to implement an integrated one health approach at village level in high-risk endemic regions, and the need to engage multiple stakeholders to formulate effective strategies for transmission risk reduction.

Discussion

Japanese encephalitis (JE), a vector-borne viral disease, is endemic to large parts of Asia and the Pacific regions [16]. An estimated 3 billion people are at risk, and the disease has recently spread to new territories globally [17]. JE is a major public health challenge due to its high epidemic potential, high case–fatality and neuropsychiatric squeal among survivors. JE was first recognized in Japan in 1924. Since the late 1960s, the size of epidemics in Japan and the People’s Republic of China has steadily declined. In contrast, new epidemic foci of JE were reported in the parts of tropical southeastern Asia as late as 1969 [18].

The JE disease is predominantly found in rural and per urban settings, where humans live in closer proximity to these vertebrate hosts. In most temperate areas of Asia, JEV is transmitted mainly during the warm season, when large epidemics can occur. In the tropics and subtropics, transmission can occur year-round but often intensifies during the rainy season and pre-harvest period in rice-cultivating regions.

Japanese Encephalitis (JE)

Is an infection of the brain caused by the Japanese encephalitis virus (JEV).While most infections result in little or no symptoms, occasional inflammation of the brain occurs [19]. In these cases symptoms may include headache, vomiting, fever, confusion, and seizures and this occurs about 5 to 15 days after infection [20].

Japanese encephalitis virus is generally spread by mosquitoes, specifically those of the Culex type and pigs and wild birds/ water birds serve as a reservoir for the virus. The disease mostly occurs outside of cities and diagnosis is based on blood or cerebrospinal fluid testing [21]. Twentyfour countries in the WHO South-East Asia and Western Pacific regions have Japanese encephalitis virus transmission risk, which includes more than 3 billion people. 21 Japanese encephalitis viruses are transmitted to humans through bites from infected mosquitoes of the Culex species (mainly Cx. tritaeniorhynchus). Humans, once infected, do not develop sufficient viraemia to infect feeding mosquitoes. Prevention is generally with the Japanese encephalitis vaccine, which is both safe and effective. Other measures include avoiding mosquito bites. 21 Once infected there is no specific treatment, with care being supportive. This is generally carried out in hospital.20 Permanent problems occur in up to half of people who recover from encephalopathy. 21 In Pantanaw Township, Ayayawady Region JE vector Cx tritaeniorhynchus was collected in highest density in Pathew 30.22%, Kyonthet 32.08% and Aque 24.16 expect Kyontonekalay 20.04% and suspected vector Culex vishnui was highest density in Kyontonekalay 24.59 and followed in remaining villages. Both species are very common, widespread and new JE cases were reported in 2017 in Pantanaw [22]. The larvae of Cx tritaeniorhynchus, Cx. quinquefasciatus Cx. vishnui and An. minimus were collected from rice field water in highest density and followed by Brick kiln, ponds, slowly running water, stream, creeks, and footprints and also the larvae of main vector Cx tritaeniorhynchus and secondary vector Cx. vishnui were observed in Toilet water containers, Marshes around the irrigation ditches, hyacinth vegetation and polluted water pools. Other species Cx. quinquefasciatus, Cx. gelidus, Mansonia species and some Anopheles species as An. minimus, An. vagus, An. maculatus, An. tessellatus and An. barbirostris were collected by animal bait collection, cow sheds, pig farms and CDC light trap collection. A study in Lapadan Township observed that highest number of main JE vector Culex tritaeniorhynchus and secondary vector Cx vishnui adult were collected by Cattle and pig farm collection and their larvae were abundantly collected from Rice field water and polluted water pools in Lapadan Township, Bago Region (Maung Maung Mya et al., already submitted for publication in MHSR Journal). Other researchers report that the most important vector is Cx. tritaeniorhynchus, which feeds on cattle in preference to humans. It has been proposed that moving swine away from human habitation can divert the mosquito away from humans and swine. The natural hosts of the Japanese encephalitis virus are birds, not humans, and many believe the virus will therefore never be completely eliminated [23]. A South Korea researcher observed that in November 2011, the Japanese encephalitis virus was presented in Cx. bitaeniorhynchus mosquitoes [24]. The common domestic animals include cows, buffaloes, goats, pigs, dogs and horses are available in Pantanaw. The pig is known to be the amplifier host of the JE virus (JEV). Despite this knowledge, unorganized piggeries and Pig farms are common in the study areas of the Ayeyawady Region. Many species of Culex mosquitoes can transmit JE. For Southern Asia, Eastern Asia, and Southeastern Asia, the main vector of JE is Cx. tritaeniorhynchus. For Northern Australia, the main vector is Cx. annulirostris. However, various other secondary vectors may be important [25].Vectors observation study in India by Indian researchers they also revealed that Japanese encephalitis virus isolation has been made from a variety of mosquito species. Culicine mosquitoes mainly Cx. vishnui group (Cx. tritaeniorhynchus, Cx. vishnui and Cx. seudovishnui) are the major vectors of JE in different parts of India. In Anopheles group as An. barbirostris An. paeditaeniatus and An. subpictus isolates and Mansonia group as Ma. annulifera Ma. indiana and Ma. uniformis isolates were found JE virus positive [26]. Cx. vishnui groups are present in many countries of south-east Asia [27,28]. These mosquitoes are usually found in rural rice growing and pig-farming regions of Asia, but can also be found at the outskirts of cities in close proximity to human populations. They prefer to breed in rice fields, and outbreaks of JE are commonly associated with intensive rice cultivation [29,31]. Other researcher revealed that these vectors are primarily outdoor resting in vegetation and other shaded places but in summer may also rest in indoors. And breed in water with luxuriant vegetation mainly in paddy fields and the abundance is related to rice cultivation, shallow ditches and pools [32]. Main vector Cx tritaeniorhynchus and secondary vectors Culex vishnui, An. barbirostris and Mansonia group are in principally cattle feeders, though human and pigs feeding are also recorded in some areas. Japanese Encephalitic Virus is maintained in a zoonotic cycle, which can be both enzootic and epizootic. This cycle involves pigs as the major reservoir / amplifying host, water birds as carriers and mosquitoes as vectors. A Indian researcher revealed that in Thanjavur District, Tamil Nadu, India the Culex vishnui subgroup of mosquitoes consisting of Culex tritaeniorhynchus Giles, Culex vishnui Theobald and Culex pseudovishnui (Colless) have been implicated as major vectors of JE [33]. In the present study villages over 80% of JE vaccination covered under15 age group, although JE transmission risk is very high in remaining children in Pantanaw Township, and need to control mosquito population to reduce JE transmission risk. Study reveals the abundance and prevalence of the major vector Cx. tritaeniorhynchus and secondary vector Cx. vishnui in studied villages in Pantanaw Township. JE vector abundance recorded is a measure of the maximum number of vector mosquitoes prevalent in these areas and this will enable village’s people and authority concerns to develop appropriate vector control strategies.

The natural cycle of JE virus in Asia involves water birds and Culex mosquitoes. However, unlike many other mosquito-borne diseases, an amplifying host is important in the epidemiology of human JE. In Asia, pigs are considered to be the most important amplifying host, providing a link to humans through their proximity to housing [34].

Countries which have had major epidemics in the past, but which have controlled the disease primarily by vaccination, include China, South Korea, Japan, Taiwan and Thailand. Other countries that still have periodic epidemics include Vietnam, Cambodia, Myanmar, India, Nepal, and Malaysia. Japanese encephalitis has been reported in the Torres Strait Islands and two fatal cases were reported in mainland northern Australia in 1998. There were reported cases in Kachin State, Myanmar in 2013. The spread of the virus in Australia is of particular concern to Australian health officials due to the unplanned introduction of Cx. gelidus, a potential vector of the virus, from Asia. However, the current presence on mainland Australia is minimal. There had been 116 deaths reported in Odisha's backward Malkangiri district of India in 2016. The highest number of cases occurred in children aged between 0 and 10 years: 47% in 1985, 60% in 1988, 88% in 2004, and 94% in 2006 outbreaks, respectively [35].

Risk Factor: Pig farms are situated very close to human households. They are 5-15 meter away between pig farms and households. In each village, 20 to 50% of the households have 1-15 pigs reared in one to two pig farms and 90% of the pig farms are open type. Main JE vector breeding sites as polluted water creeks, pools, rice fields and gutters are available in villages. Rice fields and creeks are situated beside the villages and Culex larvae were abundantly presented in rice field water. Most of the villagers and their family members have not used mosquitoes net when they go to sleep. Rice farming, pig rearing and rural population are the contextual risk factors for

JE [36,37]. Culex tritaeniorhynchus, the primary vector of JEV is found mainly in irrigated rice fields and JE is concentrated mainly in countries where extensive irrigated rice agriculture system [38,39].

Other researcher from Nepal was studied to examine the occupational risk of pig farmers in Nepal and to determine their level of knowledge and practice of JE prevention techniques. He found that pig farmers were exposed to many JE risk factors including poverty and close proximity to pigs, rice paddy fields and water birds, which are the definitive hosts for the virus. Forty?two percent of the farmers had heard of JE, 20% associated it with mosquito bites and 7% named pigs as risk factors. Few protective measures were taken. None of the farmers were vaccinated against JE nor were any pigs, despite an ongoing human vaccination campaign. This farming community had little ownership of land and limited education (Dhakal et al., 2012) [40]. In the present study revealed that 56% of the community members cited JE transmission from pigs, 8.7% from cows/buffaloes and 20.6% from water birds. They recognized high risk among under 5 children (54.4%), those between age 5-15 years (34.4%) and pig farmers (16.3%). Nearly 70% of respondents gave high priority to under five children for JE vaccination compared to between 5 to 15 years (45%) that required attention. Qualitative strand further elucidated their opinions towards health talks at their villages by health staff in coordination with local authorities and to communicate at schools for sharing information to the teachers identified as the best channel to reach the community. Focus group discussants revealed popular measures to prevent mosquito bites. Findings highlighted the issues not only to improve awareness of JE in the community but also to reduce transmission risk and fill knowledge gaps to implement an integrated one health approach at village level in high-risk endemic regions, and the need to engage multiple stakeholders to formulate effective strategies for transmission risk reduction. Un planed pig farming, high temperature, high humidity; vast rice fields and flourishing pig production are responsible for endemicity the JE in Pantanaw Township Ayeyawady Region and same pattern of JE problem was observed in Terai region in Napal [41,42]. Current and future approaches to the diagnosis and control of JEV

The detection of JE vectors and JE virus infection is problematic due to the short duration of viremia and the asymptomatic nature of infection. These factors present a challenge to obtaining a definitive diagnosis of JE virus infection and vectors of JE or for establishing prevalence levels in livestock populations and density of vector mosquitoes. Therefore, diagnosis relies on the use of a combination of epidemiological, clinical, serological pathological and entomological findings. Study observed the abundance and prevalence of the major vector Cx. tritaeniorhynchus in Pantanaw Township Ayeyawady Region. JE vector abundance recorded is a measure of the maximum number of vector mosquitoes prevalent in this area and this will enable people to develop appropriate vector control strategies.

Various challenges for JE prevention and control include - (i) land use pattern and rice cultivation - paddy is not only the staple food, but also is a major economic activity and key source of employment and income generation in the country. Paddy farming is carried out all over the country. In Myanmar a stronger association is found to exist between JE incidence and percentage of irrigated land, mainly the paddy field. However, sudden improvements in agricultural practices are not feasible 40 (ii) growing pig husbandry without sanitary and hygienic consideration: Government has been prioritizing pig farming as the potential means of alleviating poverty. The small investment and relatively higher return in pig farming has attracted all class of people in these areas. The farms are however, maintained under unsanitary practices [43]. iii Climate change and vector adaptation to high altitude region (iv) Close pig-human-rice field interaction (v) poverty and access to health care: like other tropical disease, JE also disproportionately affects the poor more frequently and more severely.

Conclusion

Pigs are main host for JE virus. Pig farms are situated very close to human household. Main JE vector, Cx. tritaeniorhynchus adult and larvae were abundantly collected in polluted water pools, rice fields and creeks in all selected villages. Secondary vectors species as Cx. vishnui, Cx. quinquefasciatus, Mansonia species and some Anopheles species An. vagus and An. barbirostris, An. maculatus adults were collected in high number in each village and malaria vector An. minimus adult was very small amount in Kyontonekalay and Kyonthet villages. High number of pig farms and JE vector Cx. tritaeniorhynchus are available in all study areas. Old and new JE history was available in both Kyontonekalay and Kyonthet villages. Therefore, the study recommended that VBDC need to give LLIN nets and health education to all family members in villages to protect JE transmission in villages. This study helps not only to improve the awareness of JE in the community but also to reduce the transmission risk and to fill the knowledge gaps of stakeholders and community members to implement an integrated one health approach at village level in high risk endemic regions. This study provides further information on risk of JE transmission in study areas support the vector borne diseases control programme in Myanmar. Japanese encephalitis is a public health problem, not only for Asia but for the entire world. However, JE is rising throughout Asia, because epidemics are typically noticed only after outbreaks, and because the disease may go largely unobserved in endemic regions. Environmental and ecological factors are responsible for the spread of JEV. Control may be possible only after developing a strong surveillance system together with a high-quality immunization program. Implementation of a vaccination program for young children, as well as modified agricultural practices, pig vaccination, rigorous monitoring, vector control, and improved living standards can reduce the number of JE cases.

Acknowledgements

The authors are thankful to the Ministry of Health and Sports for supporting the IR grant to do this research. We would like to thank Dr. Kyaw Zin Thant former Director General Department of Medical Research for permission to do research. We thankful to Township Medical Officer, authority concerns from villages and Township, and VBDC members who were helpful during the study period. We also thank the staff of Medical Entomology research Division, Department of Medical Research for general help. Sincere thanks for providing financial support over the many fruitful years of entomological research.

Competing Interest

The authors have declared that no competing interests exist.

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