Meteorological Conditions Associated with AES/JE Outbreak 2019 in Bihar - Open Journal Systems

 
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Meteorological Conditions Associated with AES/JE Outbreak 2019 in Bihar - Open Journal Systems
Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7   765

 Meteorological Conditions Associated with AES/JE Outbreak
                        2019 in Bihar

                          SC Bhan1, Anand Shankar2, Ragini Mishra3, GS Shilpashree4
    1
     Scientist F, India Meteorological Department, New Delhi, 2Scientist B, India Meteorological Department,
    Patna, 3State Surveillance Officer, IDSP, State Health Society, Bihar, Patna, 4Senior Research Fellow, India
                                       Meteorological Department, New Delhi

                                                        Abstract
    Analysis of the incidences of AES during 2019 over Bihar brought out the highest incidence of AES cases in
    June (78.5%) followed by July (12.6%). A similar pattern was found in the number of deaths associated with
    AES. Maximum incidences were reported from Muzaffarpur (559) and East Champaran (113) districts in
    north Bihar; and Gaya in south Bihar (72). More than 50% of the incidences and deaths were reported from
    children up to the age of 5 years; and more than 90% from children up to the age of 10 years indicating high
    vulnerability of children. Female children were found to be impacted more with 53% of the total incidences
    and 58% of the total deaths.

    The highest percentage of AES cases (78.5%) were reported in June followed by July (12.6%). The highest
    percentage of deaths were reported in June (69.5%) followed by July (19%). An analysis of the incidences of
    AES cases in the worst affected district (Muzaffarpur) shows a high degree of correlation with the maximum
    temperature of the past few days. A second-degree polynomial best described the relationship between the
    mean maximum temperature of the last two days and the incidence of AES cases in Muzaffarpur district
    (R2=0.74).

    Keywords:- Mean Maximum Temperature, Acute Encephalitis Syndrome, AES, Heat Index, Monsoon, Bihar,
    Muzaffarpur

                     Introduction                               remains unknown in 68-75% of patients4. The history
                                                                of AES in India is documented in association with JE,
     Acute Encephalitis Syndrome (AES) defined as acute
                                                                with the virus first being reported from southern India
onset of fever and a change in mental status including
                                                                in 1955. The sources of viral infection resulting in AES
symptoms such as confusion, disorientation, or inability
                                                                may differ across regions5. The most common of AES is
to talk and/or new onset of seizures excluding febrile
                                                                Japanese encephalitis (JE) - a vector-borne viral disease
convulsions is thought to be caused by a wide variety of
                                                                caused by the JE virus of group B arbovirus (Flavivirus)
conditions. Multiple factors like viruses, bacteria, fungi,
                                                                and is transmitted to humans by the Culicine Mosquito.
parasites, and toxins may cause AES1. It is estimated that
                                                                JE generally affects the central nervous system and
a population of 375 million is at risk of acquiring AES
                                                                can cause serious complications and death with a
in India2. Besides the JE virus, other viruses that have
                                                                high fatality rate6. The survivors may also experience
resulted in a high incidence of AES in India are Dengue
                                                                convulsions, episodic headache, abnormal behavior,
virus, Entero-virus, Herpes Simplex Virus, Measles
                                                                intellectual deficit, incoordination of movements, jerky
and Chandipura virus3. However, the etiology of AES
                                                                limb movements, speech disorder, cranial nerve palsy,
                                                                gaze palsy, parkinsonian features, impaired hearing, etc.
Corresponding Author:                                           Incidence is high among the children due to a lack of
SC Bhan, Scientist F,                                           immunity from natural infections. The disease has a high
India Meteorological Department,                                rate of death (about 25%) among the infected children.
Mausam Bhawan, Lodhi Road, New Delhi-110003                     About 30% - 40% of the survivors suffer from physical
Meteorological Conditions Associated with AES/JE Outbreak 2019 in Bihar - Open Journal Systems
766    Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7

and mental impairment7. The disease was first recognized         Warning Signals for the AES outbreak and thus help
in Japan in 1924. JE has been reported to be endemic in          in the preparedness of the Health Sector to prevent any
large parts of the Asia and Pacific regions, especially in       future impending outbreaks in the State.
the South Asian and Western Pacific regions8. Nearly
42% of 3187 reported cases of JE were from countries in                              Climate of Bihar
the South-East Asia region, with India alone accounting               Bihar is a land-locked state that mainly comes under
for about 80% of these cases. JE has been identified             the climate type subtropical monsoon, mild and dry
as the primary cause of the syndrome8. Tiwari et al.             winter, hot summer except the districts of Jamui, Banka,
attributed a fatality rate of 30%–50% to JE in southern          Munger, Lakhisarai, Khagaria, Sheikhpura and some
and eastern Asia. The outbreaks of JE in Gorakhpur               parts of Bhagalpur, Saharsa and Begusarai located in
and Basti divisions in eastern UP during 2005, led to            the extreme southeastern part of the State which comes
the development of surveillance guidelines for AES               under the type Tropical Savanna, Hot seasonally dry13
and JE by the National Vector Borne Disease Control              (usually winter). May is the hottest month with a mean
Programme (NVBDCP). These guidelines required JE                 maximum temperature of about 37OC in the plains.
to be reported as an AES and after confirmation from the         The mean maximum temperature ranges from 34OC
sentinel sites, a line-list of JE cases needed to be drawn       to 40.5OC over the state during May with the southern
and sent in prescribed formats9. Outbreaks of acute              parts of the state being the hottest and the northern parts
encephalitis syndrome (AES) have occurred previously             being the coldest. In January, the minima of the mean
in the northern regions of Bihar state and eastern               minimum temperature are observed over the eastern
regions of Uttar Pradesh state of India. The first case          region of the state. The skies are heavily clouded during
of AES in Muzaffarpur district was recorded in 1995.             the South West Monsoon season (June-September),
Muzaffarpur district, suffers repeated epidemics of acute        particularly during July and August13.
encephalopathy in children for the past 16-17 years.
Initially, the focus of the disease outbreak was limited            The total average annual rainfall of the state is
to the Muzaffarpur district but the recent trend shows           1194.9 mm with an average of 50 rainy days.
that it has spread to many other districts in Bihar10.
                                                                      The Southwest monsoon sets in over eastern parts of
Extreme heat and humidity of Muzaffarpur causing heat
                                                                 the state by about the middle of the second week of June.
stroke leading to encephalopathy along with a sudden
                                                                 July and August are the rainiest months, accounting
drop in cases when the rains set in and the temperatures
                                                                 individually, to about 28% and 24% of the annual
dropped has also been reported in a study11. As per
                                                                 rainfall, respectively. Withdrawal of the southwest
reports of State Surveillance Unit, IDSP, State Health
                                                                 monsoon begins from the northern parts of the state in
Society Bihar, the peak of the AES outbreak in Bihar
                                                                 the first week of October13.
has been observed in June that has been consistent since
the last five years12. The total cases & number of deaths                        Data and Methodology
reported in 2017, 2018 & 2019 in Bihar has been 268 &
56; 179 & 45, and 1089 & (236), respectively. In 2019,                Bihar is one of the 36 Metrological subdivisions
AES cases were reported from 34 districts in the State.          of India with four Departmental observatories at
The majority of the cases were reported during 2019              Patna, Gaya, Bhagalpur and Purnea, and seven part-
were from Muzaffarpur followed by East Champaran,                time Observatories. Meteorological data from one of
Vaishali, and Gaya. The age group most affected was              the observatories located in Muzaffarpur city has been
0-5 years (53.44%) and 5-10 years (37.37%). Females              used for analysis in this study. Data on the incidence of
(53.16%) were more affected than males (46.83%).                 AES cases (known and unknown) and associated deaths
                                                                 were collected from the daily reporting and monitoring
    The present report informs about the epidemiology of         of the cases being done by the State Surveillance Unit,
AES in Bihar as well as its meteorological interpretation.       Integrated Disease Surveillance Programme. The
The report also highlights the use of meteorological             program regularly shares the data with concerned district
data to establish co-relation with the AES outbreak.             administration for proper and timely intervention to
The meteorological data may be used to generate Early            control the disease outbreak (Source: State Surveillance
Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7    767

Unit, IDSP, State Health Society, Bihar).                      observed in the reported number of deaths with the
                                                               highest number of deaths (110) Muzaffarpur followed
               Results and Discussion                          by Purbi Champaran (26), Vaishali (20), and Sitamarhi
    Analysis                                                   (19). Gaya district in south Bihar reported 16 deaths.
                                                               The geographical distribution of total AES cases is given
     Changes in weather patterns and precipitation affect      in Figure 2. Similar distribution has been reported in the
the evolution of many infectious vector-borne diseases         state earlier also13.
like Malaria, Chikungunya, Japanese Encephalitis,
Filariasis, etc. It has found that Acute Encephalitis               Agewise and genderwise distribution:
Syndrome (AES), a deadly brain disease generally
                                                                    Almost all of the 1081 AES cases were from the
affects children of age between 0-15 years. Normally,
                                                               Children aged between 0-15 years with maximum
the children experience symptoms like sudden falls
                                                               impacts on children in the age group of 0-5 years
in blood sugar which ultimately causes death. There
                                                               (53.2%). 37.6 % of cases were from the age group of
were a total number of 1089 AES known and AES
                                                               5 to < 10 years and 8.6% from 10 to < 15 years ago.
unknown cases reported across the Bihar during the
                                                               Only 3 cases of age 15 years or more were reported. Of
year 2019. Seven of these cases were from the adjoining
                                                               the 232 cases of AES related deaths, 52.6 % were from
state of Jharkhand and one from Nepal. Out of these
                                                               the age group less than 5 years, 38.4% from 5 to less
1081 cases, 232 (21.5%) cases reported death. Out of
                                                               than 10 years, and 8.2% from 10 to less than 15 years.
the total 715 known cases of AES, 554 (77.4 %) were
                                                               The highest number of deaths in all the age groups were
of Hypoglycemia and 130 (18.2%) were of Japanese
                                                               reported from Muzaffarpur district. Female children
Encephalitis. Out of all known cases of AES, 23.15 %
                                                               were found to be impacted slightly more by AES. Out
of patients died because of Hypoglycemia, Japanese
                                                               of the total 1081 reported cases, 46.8% were male and
Encephalitis, etc. A description of all the 1089 cases is
                                                               53.2% were female. Out of the total 232 AES related
given in Table 1.
                                                               deaths, 98 were male and 134 were female (Table 2).
    Temporal Distribution:-
                                                                   Relationship of AES incidence with temperature
     Month-wise incidences of AES cases and associated         in Muzaffarpur district:
deaths are given in Figure 1 below. The highest
                                                                    As the highest number of cases were reported in
percentage of AES cases (78.5%) were reported in June
                                                               Muzaffarpur district, a detailed analysis of its relationship
followed by 12.6% in July and 3.2% in August. Similarly
                                                               with temperature carried out for Muzaffarpur district
the highest percentage of deaths were reported in June
                                                               for the month of June as the month accounted for about
(69.5%) followed by July (19%) and August (6%). The
                                                               90% of the cases. Correlation coefficients (CC) were
outbreak of AES occurred mainly from 4th June 2019
                                                               found between the incidences of AES and maximum
to 26th June 2019. The cases significantly decreased
                                                               temperature of the previous day; and the mean maximum
after the onset of Monsoon in Bihar (23rd June 2019).
                                                               temperatures of previous 2, 3, 4, 5, 6, and 7 days. The CC
This seasonal distribution is very similar, to the monthly
                                                               was 0.79 with the maximum temperature of the previous
pattern of AES in Bihar reported earlier14.
                                                               day; and 0.82 with the mean maximum temperature of
    Spatial Distribution:-                                     the previous 2 days. Correlation coefficients were also
                                                               computed between AES incidences and Heat Index for
    Acute Encephalitis Syndrome (AES) cases were               the day. The highest correlation coefficient of 0.56 was
reported from all parts of Bihar except the districts of       found with the heat index of previous day. The plot
Gopalganj, Bhabhua, Khagaria, and Lakhisarai. Highest          of the day to day incidences of AES against the mean
numbers of cases were reported from central districts          maximum temperatures of the previous 2 days given in
of north Bihar, i.e., Muzaffarpur (559) followed by            Figures 3 shows that the incidences of AES generally
Purbi Champaran (113), Vaishali (86) and Samastipur            fluctuated with maximum temperatures. Scatter plot of
(57). Gaya district in south Bihar also reported a high        AES incidences against the maximum temperature of
number of incidences (72). A similar pattern was also          the previous day and the mean maximum temperature
768     Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7

of the previous 2 days given in Figure 4 show that the                  Units of Measurements
number of AES cases increased exponentially with
                                                                        Temperature:- Degree Celsius (ºC).
increase in temperature. A second degree polynomial
was found to best defines the variability in AES cases                  Abbreviations and Symbols
with an R2 value of 0.74. The average numbers of cases
were 2.6 cases on the days when maximum temperatures                 AES: - Acute Encephalitis Syndrome, JE: - Japanese
were 33 to 35 Deg C. These were 15.4 and 19.6 on days             Encephalitis, JES: - Japanese Encephalitis Syndrome
with temperature 35 to 37 Deg C and 37 to 39 Deg C;

    Table 1. Analysis of AES Cases in Bihar during 2019

Description                                                                Total Cases            Deaths

Total AES                                                                  1089                   236

Total AES Unknown                                                          372                    70

Total AES Confirmed                                                        717                    166

JE +ve                                                                     130                    27

Meningitis/ Meningoencephalitis /Tubercular Meningitis/Pyogenic/Aseptic
                                                                           6                      0
Meningitis./Acute Meningococcal

Herpes/Measles/ Pox/Mumps/Viral Encephalitis                               7                      3

Hypoglycemia                                                               554                    134

Dyselectrolytemia                                                          3                      2

Chicken Pox                                                                1                      0

Others: Heatstroke, Hyper-pyrexia.                                         16                     0

    Table 2. Age and gender wise distribution of total AES cases

                               Age/Gender                          Number of AES Cases              Number of Deaths

                               < 5 years                           582                              125

                               5 to
Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7   769

Figure. 1. Monthwise distribution of AES cases and reported death of Bihar in 2019.

                         Figure. 2. Districtwise Distribution of AES cases in Bihar
770    Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7

 Figure. 3. Day to day incidences of AES cases in Muzaffarpur district and Mean Maximum Temperature of Previous 2 days
                                                     during June 2019

Figure. 4. Relationship between AES cases and Mean Maximum Temperature of Previous two days for Muzaffarpur, June, 2019
and 52.8 on days with temperature more than 39 Deg C.

                      Conclusion                                     In the most affected district – Muzaffarpur, the
    Analysis of AES incidence during summer 2019                 incidences of AES was found to have a very high
brought out that maximum impact was on children in the           correlation (0.82) with maximum temperature with a
age group of 0-5 years (53.2%) with only 8.6% from 10            lag of two days during the month of June. Increase in
to < 15 years ago. Of 232 cases of AES related deaths,           number of AES cases with maximum temperature brings
52.6 % were from the age group less than 5 years.                out a possibility that advance warning on temperature
Indian Journal of Public Health Research & Development, July 2020, Vol. 11, No. 7   771

could help the health system prepare better to combat                1143-1148.
the AES.                                                       7.    Government of India. Operational Guidelines:
                                                                     National Programme for Prevention and Control
     Ethical Clearance: Not Required
                                                                     of Japanese Encephalitis/Acute Encephalitis
     Source of Funding: Self                                         Syndrome. National Vector Borne Disease
                                                                     Control Programme, Directorate General of Health
     Conflict of Interest: Nil                                       Services, Ministry of Health and Family Welfare.
                                                                     New Delhi. 2014.
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