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correspondence

Indian Pediatr 2012;49: 502-503

Recurring Epidemics of Acute Encephalopathy in Children in Muzaffarpur, Bihar


Gopal Shankar Sahni

Department of Pediatrics, SK Medical College, Muzaffarpur, Bihar, India.
Email: [email protected]


Muzaffarpur district, suffers repeated epidemics of acute encephalopathy in children for the past 16-17 years. An outbreak of this mystery disease, with high case fatality (63.3%) was reported in children from Muzaffarpur district, Bihar, in June 2011. We report here our findings of the investigations carried out to confirm the etiology and to describe the clinico-epidemiological features.

Clinically, the presentation indicated Acute encephalitis syndrome (AES). We studied 80 children from age group of 2-10 (median, 3.5) years belonging to low socioeconomic background. Almost all cases were from rural area. Following clinical criteria were used to select a case of AES: Rapid onset of unconsciousness in a previously healthy child after attack of convulsion, and presence of fever >40°C.

The main presenting features were fever and convulsions (100%), unconsciousness (100%), decerebrate rigidity (50%), tachycardia (80%), tachypnea (80%), and absent splenomegaly. The CSF was normal but under raised pressure (100%). Hematological investigations revealed leucocytosis with neutrophil predominance (80%). Biochemical investigation revealed hyponatremia (90%), hypokalemia (5%), mild raised SGPT (50-100IU/L) (30%), mild raised blood urea (40-50mg/dL) (40%), and normal creatinine. Smears for malarial parasites were negative. CT scan was done in 8 cases; two showed feature of cerebral edema, rest was normal. ECG showed non-specific ST changes and tachyarrhythmia

The requisite clinical samples were collected from 55 patients and sent to National Institute of Virology, Pune and National Communicable Disease Center, New Delhi for virological testing. These included 31 CSF samples, 59 serum samples, 19 nasal swabs, 48 throat swabs, 44 rectal swabs, 2 urine samples, 2 postmortem brain needle biopsy material by nasal route, and 1 postmortem liver biopsy specimen. All clinical samples were negative for known virus causing acute encephalitis like JE, Nipah, West Nile and chandipura virus. Some specimens were processed for the discovery of novel agents. However, no agent has been found which can be attributed to the cause of the mystery disease in Muzaffarpur [1].

The presentation, seasonal distribution, climatic condition and investigations of the cases did suggest a diagnosis of encephalopathy of heat stroke (HS), as similar picture has been described in few other studies also [2,3]. Between April and June, the climate of Muzaffarpur is extremely hot and humid (28/40°C, 90% humidity) and most epidemics occurred at the height of temperature (38-40°C) and humidity (70%-80%) suggesting the possibility of HS. The number of cases suddenly decreases with the onset of rain and resultant sudden drop in temperature.

Heat stroke is a life threatening medical emergency – defined clinically as core temperature >40.6°C accompanied by central nervous system dysfunction. It is a diagnosis of exclusion. After other similar entities such as drug withdrawal syndrome, neuroleptic malignant syndrome, septicemia, cerebral malaria, CNS infection, thyroid storm, drug toxicity (anticholinergic) have been excluded [2]. Despite the advances in last 50 years, mortality due to heat stroke continues to be as high as 10-50% [3]. Since Japanese encephalitis (JE) occurs in many parts of India, especially in outbreaks, physician and investigators have a focus on JE virus. This has not been wasteful but distracts investigators from other possible explanations and etiologies. Thus, the mystery of undiagnosed outbreaks persists [4,5]. Neuro-pathological study of 15 cases of autopsy of brain, conducted by ICMR during 1967 and 1968, failed to provide any stigmata of encephalitis, but confirms the presence of "encephalopathy", caused by high environmental temperature per se or secondarily in association with other endogenous cause [6].

The disease entity has been occurring in months of May-June every year in this district of since 1995. The causative factors and mechanism, which is triggering the disease every year in this region, needs a systemic epidemiological study. For the interim, awareness on prevention of heat stroke may possibly contribute to a reduction in the number of affected children.

References

1. National Institute of Virology. Report on investigation of an outbreak of acute encephalitis syndrome (AES) in Muzaffarpur, Bihar. Director, National Institute of Virology, Pune. NIV/MCC/EPD/755, November 23, 2011.

2. Srimachari S. Heat hyperpyrexia: time to act. Indian Med Res. 2004;119:VII-X.

3. Kuan-Che Lu, Tzong-Luen Wang. Heat stroke. Ann Disaster Med. 2004;2:97-109.

4. George K. Investigating outbreaks of uncertain etiologies. Indian J Med Res. 2007;125:505-7.

5. Kumar S. Inadequate research facilities fail to tackle mystery disease. BMJ. 2003;326:12.

6. Sriramachari S, Patoria NK. Pathology of acute encephalopathy syndrome in children in summer. Indian J Med Res. 1976;64:296-313.

 

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