page_title: 2019 Bihar encephalitis outbreak
section_title: Cause
hierarchical_section_title: 2019 Bihar encephalitis outbreak / Cause
caption_attribution_description: Lychees (Litchi chinensis), picture taken at Saint-Benoît (Réunion island)
context_page_description: In June 2019, an outbreak of acute encephalitis syndrome occurred in Muzaffarpur and the adjoining districts in Bihar state of India resulting in deaths of more than 150 children, mainly due to hypoglycemia. In subsequent months more cases and deaths were reported. The cause of outbreak is unclear. Malnutrition, climate, hygiene, inadequate health facilities, and lack of awareness are considered as contributing factors. The lychee fruit toxins are also cited as plausible cause of AES.
context_section_description: The cause of the outbreak is unclear.
  AES can be caused by different microorganisms including virus, bacteria, fungi, parasites and spirochetes, as well as chemicals and toxins. AES mostly affects children below 15. In India, AES was chiefly associated with Japanese encephalitis virus (JEV) before 1975. The JEV cases and outbreaks became more frequent and endemic regions developed between 1975 and 1999. After 1999, non-JEV cases and outbreaks of AES were increasingly reported caused by other viruses including Chandipura virus (CHPV), Nipah virus (NiV), and enteroviruses. After 2012, it is observed that the cause shifting to JEV. Initial examination shows little sign of the JEV or other viral routes in the affected children. A study by AIIMS Patna found the presence of enterovirus.
  High temperature, humidity, malnutrition, poor hygiene and lack of awareness are known aggravating factors of AES. Cases of AES tend to occur during the country's monsoon season. In June 2019, the temperature in Muzaffarpur had remained above 40 °C (104 °F) and the rains were delayed which might have aggravated the situation. It was the second-longest heatwave in the region. Poverty and malnutrition is widespread among children in the region. Malnourished children lack a buffer stock of sugar as glycogen in the liver which puts them at higher risk of hypoglycemia. Awareness campaigns were carried out in March–April 2019 but were not conducted later due to the 2019 Indian general elections. The local administration was not watchful due to the few cases of AES in recent years.
  The region is the largest producer of lychee fruits in India. A 2014 study published in Lancet found that the methylene cyclopropyl acetic acid and hypoglycin A found in unripe lychee (Litchi chinensis) fruit can cause hypoglycemia and cited them as plausible cause of AES outbreaks. A diet heavy on unripe lychee fruits without having an otherwise full meal later in the day may put malnourished children at risk of hypoglycemia. Others disputed the findings citing the unlikeliness of very large consumption of unripe lychee fruits, lack of cases in healthy, well-nourished children and many other pediatric illnesses causing hypoglycemia. Health officials reported that most of the victims suffered severe hypoglycemia.
  The hospitals and primary health centres lacked the required facilities to treat children.
caption: Lychee fruits, which naturally include toxins related to encephalitis, are suspected to have been a contributing factor in the outbreak.
exif: {"Image Make": "EASTMAN KODAK COMPANY", "Image Model": "KODAK DX6440 ZOOM DIGITAL CAMERA", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "118", "EXIF ExposureTime": "1/90", "EXIF FNumber": "17/5", "EXIF ExposureProgram": "Program Normal", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2003:01:22 21:57:13", "EXIF DateTimeDigitized": "2003:01:22 21:57:13", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ShutterSpeedValue": "13/2", "EXIF ApertureValue": "7/2", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "23/10", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "11/2", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2304", "EXIF ExifImageLength": "1728", "EXIF ExposureIndex": "100", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "33", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}