Demographic profile of the Sivasagar district
Table 1 showed the demography and health care facility of the Sivasagar district of Assam. With 1024 villages, the district has a population of 11.51 lakh as per the population census 2011, Government of Assam. The rural population of the district constitutes 93.90% of the total population and shares 90.44% of the total population of Assam. The population density of the district currently stands at 431 per sq km. The district also has a high sex ratio (…). The majority community in the district is Hindu (87.51%), followed by Muslim (8.30%), Christian (2.88%) and otherslike Sikh, Buddhist, Jain (1.3%). The district has an average literacy rate of 80.41%, which is below the literacy rate of Assam (88.88%). The district has a central District Civil Hospital (DCH) located at the Sivasagar town, the headquarters of the district and two subdistrict hospitals. In addition, the healthcare system of the district comprises eight Block Level Primary Health Centers (BPHC), namely Sapekhati, Patsaku, Galekey, Khelua,Demow, Gaurisagar, Kalogaon and Morabazar BPHCs. A total of 36 PHCs, 1 community health centers (CHC), 1dispensary,4 model hospitalsand 220- PHC sub-centers work in collaboration with BPHC. The CHCs constitute the secondary level of healthcare designed to provide referrals as well as specialist healthcare in rural areas. CHCs have been envisaged as only one type and will act both as Block level health administrative units and gatekeepers for referrals to a higher level of facilities. All essential services such as routine and emergency care, medicine, Gynecology, Pediatrics, AYUSH, etc.,aremade available by CHCs. All the epidemiological disease surveillance work is carried out by PHC sub-centers distributed all across the district, and each sub-center covers about 4 to 5 villages. In addition to seven reserved beds for clinical management of JE cases, there is also a dedicated public health laboratory for JE test and serum sample analysis through IgM ELISA in DCH of Sivasagar district. In District Civil Hospital (DCH), six bedded Pediatric Intensive Care Unit (PICU) is also functioning. However, critical patients are referred to Assam Medical College & Hospital, Dibrugarh, located at Dibrugarh town for intensive care about 80 km away from district Hospital.
Table 1 Demographic profile of Sivasagar District
Parameters
|
Number
|
Population
|
1151050
|
Rural Population
|
1040954
|
Population Density (per sq km)
|
431
|
Villages
|
1024
|
Tea Estates
|
98
|
Sex Ration (Male/Female)
|
1000/954
|
Literacy Rate (%)
|
84.41
|
District Hospital
|
1
|
Sub District Hospital
|
2
|
Block PHC
|
8
|
CHC
|
1
|
PHC
|
36
|
Dispensary
|
1
|
Model Hospital
|
4
|
Sub-centers
|
220
|
Trend of AES and JE cases in Sivasagar district
Figure 1 showed the trend of AES, JE, and fatality ratesfrom 2011 to 2020 in the Sivasagar district of Assam. The overall AES and JE cases during the study periodwas found to be 1081 and 588, respectively. Similarly, the death cases were found to be 333 and 180 for AES and JE, respectively.Out of the total AES cases, 54.39% were found to be JE cases, and 54.05% deaths were reported due to JE out of 333 AES death cases. During the period of study, there was a significant decline inencephalitis cases from 2011 to 2020. The positive cases, number of deaths, and CFR were found to be the highest in the year 2011 (21.76% of total cases) followed by 2015 (11.39%), 2013, 2014 and 2017 (10.88% each)), and lowest in 2020 (3.06%). Similarly, the highest death cases were reported in 2011, followed by 2013 and 2012.However, the cases were increased in 2017 and 2019. In 2017, the cases were increased dramatically from 51 to 100 cases, an increase by double. Figure 1 also showed the Case Fatality Rate (CFR) due to Japanese Encephalitis that ranges between 13-45% during 2011 to 2020. The overall CFR of the district during the period 2011 to 2020 was found to be 28.16%. There was a fluctuation of CFR from 2011 to 2013, reaching the highest to 45.31% and lowest to 36.72%. However, from 2014 onwards, there was a significant decline (P≤0.05 level) in JE cases in the Sivasagar district.
Age-wise distribution of AES and JE cases in Sivasagar district
The prevalence of AES cases in different age-groups of Sivasagar district of Assam during the period from 2011 to 2020 is presented in Figure 3. It is found that the AES cases were significantly higher in the age-group>30 years of the district compared to a younger age. The total number of AES cases during the period was found to be 94, 185, 208, 377, and 217 cases for the age-groups 0-5, 6-15, 16-30, 31-60, and above 60 years, respectively. Age group 31 to 60 years showed the highest susceptibility to AES (34.87%), followed by age group>60 years (20.07%). Similarly, the numbers of AES death cases were found to be much higher in age-group>31-60 years, constituting about 38.44% of the total death cases of the district, followed by age- group >60 years, which is about 30.03% of total AES death in the district for the period. The lowest cases reported from children belonging to age-group 0-5 years with 8.6% of total cases. Similarly, the lowest death reported among the children belonging to age group 0-5 years with 7.2% of total death. On the other hand, there -was a steep increase of AES cases in the age-group 6-15 years during 2016-17 compared to other age groups.
Figure 3b showed the prevalence of JE cases in all the five different age-groups of Sivasagar district of Assam from 2011 to 2020. JE cases were found to be significantly different in different age-groups. Like AES, higher JE cases were observed in olderpeople (>30 years) compared to younger age-groups (<30 years). The transmission rate among children (0-5 years) was significantly less and reported at only 6.8%. 14.45% and 16.83% of JE cases were reported in the age-group 6-15 and 15-30 years, respectively. Almost 61.9% of JE cases were reported from age group above 30 years.Total 30.61% of JE death cases were reported out of the total JE cases in the district. JEdeath is significantly higher in the age-group >30 years (77.22%). 40.55% death cases were reported from age group 30-60 years and 36.66% from age group>60 years.
Sex-wise distribution of AES and JE cases in Darrang district
The gender-wise distribution of AES and JE cases from 2011 to 2020 is presented in Figure 4. It is observed from the study that both the AES and JE cases were significantly higher in male population compared to female (Figure 4). Out of 1081 cases,in our study,669 and 412 cases were reported in male and female. Both the AES and JE positive and death cases showed almost similar trends in both male and female populations. JE cases were observed in a similar pattern of occurrence in the district during the study period. Total 370 JE cases were reported in male population, while 218 cases in female population from the study area. Male and female showed significant differences (P≤0.05 level) in terms of JE susceptibility throughout study. Similarly, out of 180 JE death cases, 115 (63.89%) and 65 (36.11%) deaths were reported in males and females. It has also been observed that the JE cases were much higher in the male population in almost all the age-groups. The percent of JE cases and mortality reported in male and female population of the district during the study period is shown in Figure 4d. Correlation study revealed that an increase in male or female cases has significant relation (P≤0.01level) to AES or JE cases.
Seasonal prevalence of AES and JE cases in Sivasagar district
The month-wise prevalence and seasonal trend of JE cases analyzed from 2011 to 2020are presented in Figure 5. It was observed that the spikes of JE outbreak starts from May every year and continues till August. Highest JE cases were reported in July followed by June almost every year from 2011 to 2020. Out of 588 JE cases during the study period, 561 cases (about 95.41%) occurred during the month from May to August. The number of cases reported in June and Julywas133 (22.62%) and 372 (63.26%), respectively. The outbreak of JE was found to be almost dormant from September to April, although few cases were reported throughout the year. Figure5 showed the seasonalvariation of JE cases during the period 2011-20. In the year 2017 and2019 the cases were reported from January and reached peak in June andJuly. However, the maximum deaths were reported only in June andJuly. The transmission of Japanese Encephalitis cases has increasedduring the rainy seasons and declined post rainy seasons.
Block-wise distribution of AES and JE cases in Darrang district
The distribution and prevalence of AES and JE cases in different blocks of Sivasagar district from 2011 to 2020are presented in Figure 6(a-h). The study reveals differences in the prevalence of AES and JE cases in all eight blocks of Sivasagar district. During the study period (2011-20), the total numbers of AES cases were 141, 221, 60, 66, 174, 57, 216, and 146 in Demow, Galekey, Gaurisagar, Kalogaon, Khelua, Morabazar, Patsaku, and Sapekhati block. On the other hand, JE cases were found to be highest in Galekey block (23.46%), followed by Patsaku (18.19%), Khelua (16.49%), Sapekhati (13.06%), Dimow (11.05), Kalogaon (6.46%), Gaurisagar (5.95%) and Morabazar (5.10%). Similarly, death cases due to AES and JE were highest in Galeky block (26.12%),followed by Khelua, Patsaku, Dimow, Sapekhati, Gaurisagar, Morabazar and Kalogaon. During the study period, the peak of encephalitis cases were recorded in 2011-14 in all the blocks, and later on, there was a decline of encephalitis cases. Thehighly affected blocks were Galeky, Patsaku and Khelua. Morabazar block found to be low endemic in comparison to other blocks. A maximum of two-four years continuous increase or decrease in the number of cases have been observed during the period of study from the block level disease surveillance. The study also revealed that both positive and death cases of AES and JE resurged in all the blocks in the year 2020 except Morabazar, which showed a decreasing fatality trend during the period of study (Figure 6f).
JE Vaccination
Vaccination is the most cost-effective therapeutic intervention to achieve long-term protection. In 2006, the Government of India launched a JE vaccination campaign for children from 0 - 15 years of age. This was followed by immunization of new cohorts as an integral component of the Universal Immunization Programme with a single dose of live attenuated JE vaccine (SA–14-14-2) in 11 highly endemic districts of four states (Assam, Karnataka, Uttar Pradesh, and West Bengal). Figure 7 showed the total population and percentage coverage under JE vaccination programme in Sivasagar district of Assam from 2011 to 2020 for the age group of 09-18 months. A total of 112932 individuals have been covered under the vaccination program out of 203361 targeted populations during the period of study (data source: district Immunization Programme, Sivasagar). It was observed that, during the launch of Routine Immunization Programme in 2011-12, the coverage was very poor (13.59%) with one dose only (age above one year). Similarly, during 2012-13 the coverage was also found to be very poor (28.03%). Later on the programme was revised to two doses of JE RI by GoI. The coverage increased in 2016-17, 2017-18, 2019-20 and 2020-21 reported above 70%. The Target population found to be similar in all the years except 2020-21. There was a slight decline in the target population and coverage in the year 2020-21 (Figure 7). The highest percentage coverage was found in 2020-21 (88.77%). Mass JE vaccination campaigns in children aged 1 to 15 years and adults 16 years above were carried out in 2011-12 with target and coverage population sizes of 583330 and 554739 (95.10%), respectively. Similarly, adult (age-group 16-60 years) JE campaign for left out in 2011-12 was carried out during 2014-15 in Sivasagar district of Assam achieving 138719 (77.49%) population coverage out of targeted 179006 population size.