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Noninflammatory encephalopathy identified in Indian neurological illness outbreak
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Outbreaks of severe neurological illness with high mortality rates among children in India have been identified as acute noninflammatory encephalopathy, according to a report from the CDC.
Researchers noted that prior investigations of this syndrome have indicated a possible association between the outbreaks and exposure to pesticides from litchi fruit that are grown in the Muzaffarpur district of India.
“The outbreaks generally peak in June and decline weeks later with the onset of monsoon rains,” Aakash Shrivastava, MD, from the Indian National Centre for Disease Control, and colleagues wrote. “There have been multiple epidemiologic and laboratory investigations of this syndrome, leading to a wide spectrum of proposed causes for the illness, including infectious encephalitis and exposure to pesticides.”
An increase in ED admissions and hospitalizations for severe neurological illness among 133 children was reported to the CDC by two main referral hospitals in Muzaffarpur from May to July 2013. Patients aged younger than15 years demonstrated acute onset seizures or altered mental status within 7 days of admission; 44% of admitted patients died.
Sixty-one percent of patients were afebrile at admission. Among 56 patients whose cerebrospinal fluid was examined:
- 55% exhibited normal cytology (white blood cell count ≤ 5/mm3);
- 81% had cerebrospinal fluid normal protein levels (< 45 mg/dL); and
- 75% had normal cerebrospinal fluid glucose (> 45 mg/dL) levels.
At admission, 21% of patients exhibited hypoglycemia with a blood glucose of less than 70 mg/dL.
In a secondary outbreak investigation, 390 children with neurological illnesses that matched the previous case definition were admitted to the two referral hospitals in Muzaffarpur from May to July 2014.
Building on the earlier investigation, researchers conducted facility-based clinical surveillance, epidemiologic case-control and environmental studies and laboratory evaluation for infectious pathogens as well as selected pesticides, heavy metals and naturally occurring toxins.
Additionally, patients admitted with the suspected outbreak illness were immediately tested for hypoglycemia upon arrival and before any treatment. Admitted patients were recommended to receive intravenous dextrose therapy.
Among 345 patients with available data, 94% exhibited seizures at admission, while 77% demonstrated altered mental status; 31% of admitted patients died.
In 62 patients whose cerebrospinal fluid was examined, 84% had normal white blood cell counts, 94% had normal protein, and 79% had normal glucose levels. Among 327 patients whose blood glucose was measured on admission, the median blood glucose level was 48 mg/dL; 52% of patients had glucose levels of no more than 50 mg/dL, and 62% exhibited levels of 70 mg/dL or lower.
“The low blood glucose raised the possibility that exposure to a toxin could result in low blood glucose, seizures, and encephalopathy,” the researchers wrote.
While diagnostic tests of cerebrospinal fluid were negative for common regional infectious encephalitis pathogens, the researchers said the pattern of outbreaks coincided with the monthlong litchi harvesting season in and around Muzaffarpur.
“Although the underlying cause of this illness remains unknown, initial clinical and laboratory results of the 2014 investigation confirm the importance of systematically evaluating toxins and agents with the potential to cause acute encephalopathy,” Shrivastava and colleagues wrote.
Disclosure: The researchers report no relevant financial disclosures.
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