INTRODUCTION
Acute Encephalitis Syndrome (AES) is defined by WHO as follows: “Clinically any person of any age at any time of year having acute onset of fever and a change in mental status which involves signs and symptoms such as confusion, disorientation, coma, or inability to talk and/ or new onset of seizures (excluding simple febrile seizures).” Viruses have been majorly attributed to be the cause of AES in India albeit other sources such as, fungus, parasites, bacteria, spirochetes, chemical, and toxins have also cropped up over the past few decades.
In India, AES was clinically diagnosed for the first time in 1955 in Madras now Tamil Nadu. Currently ,the disease is endemic in nearly 171 districts in around 19 States. Between the time span of 2008 and 2014, there have been over 44,000 cases and around 6000 deaths from AES in India, particularly in the states of Bihar and UP.
AETIOLOGY (CAUSE) OF AES
Encephalitis is a complex syndrome of multiple aetiologies , though Japanese encephalitis virus (JEV) is the leading diagnosed cause in our country. JEV is a common mosquito borne flaviviruses , prevalent mostly in eastern and southern Asia, covering a region having population of over three billion. [3] Other causes include enteroviruses , scrub typhus, measles and other viruses (non JEV outbreak) circulating in the local area. Thus , the disease spectrum of AES seems to be wide .
AES/JE cases reported from 2013 to 2018 in India
The history of AES in India is divided into 3 phases:
(a)First phase: Period before 1975 when only a few cases with JE etiology were identified.
(b) Second phase :between 1975 and 1999 when more JEV cases were reported with frequent outbreaks led to the development of JE endemic regions near the Gangetic plains as well as parts of Deccan and Tamil Nadu.
(c)Third phase : between 2000 and 2010, a dramatic change was observed in the AES scenario, which saw the rise in non-JE outbreaks mostly caused by viruses such as Chandipura virus (CHPV), Nipah virus (NiV), and other enteroviruses .
OUTBREAK OF AES IN THE COUNTRY
In the states of Bihar, West Bengal, UP, Bihar, Assam, and Tamil Nadu were recognized as JEV endemic zones. In 2013, beginning from the monsoon months till the cease of November, 2,205 people were notified to be infected by JEV, and the death toll grew to 590 . In 2014 , many cases of AES were reported from the states of Assam (2,195 cases, 360 deaths), West Bengal (2,381 cases, 169 deaths), UP (3,329 cases, 628 deaths), and Bihar (1,384 cases, 356 deaths) .JEV was the major reason of these deaths though virologists also identified another causative agent in the form of a ‘toxin-mediated illness’.
In June 2019, an outbreak of AES happened in 222 blocks of Muzaffarpur and the adjoining districts in Bihar. The outbreak resulted , in the death of total 154 children and a total of 400 cases were reported in the first three weeks of June 2019. Approximately 85 children of them died at the Sri Krishna Medical College and Hospital (SKMCH), the largest state-operated hospital in the state of Bihar, while at least 18 children died at the Kejriwal Matrisadan, a trust-run hospital .Most of them were aged between 1 and 10 years. Total 647 cases of AES including 161 deaths were diclosed between 1 June and 20 September 2019.
Association of acute toxic encephalilitis with litchi consumption in an outbreak in Muzaffarpur, India
A study done recently has also postulated a relationship between consumption of litchi and AES16. This case-control study points that the outbreak has emerged from toxicity following consumption of litchi fruits, which contains compounds like hypoglycin A and methylene cyclopropylglycine (MCPG). The study further claims to have evidenced the presence of MCPG and hypoglycin in litchi and the metabolites of these toxins in human biological specimens. The study however, did not contrast litchi-associated cases with the controls taken from the infected community but with sick controls lacking neurological disease and no history of altered mental status or seizures in the previous three months and admitted to a case-surveillance hospital less than seven days from admission of the case.
CONCLUSION
It was inferred from the given reading that acute encephalitis syndrome (AES) is serious problem in India sporadically showing several time since it was first clinically diagnosed in madras in 1955. Japanese encephalitis virus (JEV) is attributed to be the major cause of AES in the country though other causative organisms are also there. There is seasonal and geographical variation in the causative organisms among AES cases. The symptoms of the disease are quite similar to other neurological disorders. The pattern of disease spread is shown to be pediatric causing considerable morbidity and mortality in children and young adults.
REFERENCE
WHO – recommended standards for surveillance of selected vaccine-preventable diseases Geneva :WHO; 20:00876
Webb JK, Perreira SM. Clinical diagnosis of arthropod borne type viral encephalitis in children in North Arcot district, Madras State, India. Indian J Med Sci. 1956;10:572.
Guidelines clinical management of Acute Encephalitis Syndrome including Japanese Encephalitis. Government of India. Directorate of National Vector Borne Disease Control Programme 22, Shamnath Marg, Delhi-110054 Directorate General of Health Services, Ministry of Health & Family welfare .
Joshi R, Kalantri SP, Reingold A, Colford JM Jr: Changing landscape of acute encephalitis syndrome in India: a systematic review. Natl Med J India 2012;25:212–220.
Ghosh, S., & Basu, A. (2016). Acute Encephalitis Syndrome in India: The Changing Scenario. Annals of Neurosciences, 23(3), 131–133.
Heat, lack of nutrition, awareness add to AES, Bihar kids toll over 100". The Indian Express. Indian Express Group. 18 June 2019. OCLC 70274541. Archived from the original on 18 June 2019. Retrieved 18 June 2019.
By Medha Varshney
gaurimv25@gmail.com
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