Resurgence of Chandipura Virus Encephalitis in Western India, 2026: A Descriptive Surveillance Analysis of Test Positivity and Case Fatality, with Implications for Laboratory Diagnostics
Ajit Pal Singh
*
Department of Medical Lab Technology, School of Allied Health Sciences, Galgotias University, Greater Noida, Uttar Pradesh 203201, India.
Singh Aryan Joseph
Samarkand State Medical University, Samarkand 140104, Uzbekistan.
Maria Agbo-Inedu Ihotu Owoicho
Jos University Teaching Hospital, Jos, Plateau State 930001, Nigeria.
Rahul Saxena
Department of Biochemistry, School of Allied Health Sciences (SSAHS), Sharda University, Greater Noida, Uttar Pradesh, India.
Ali Saad Al-Budairi
Branch of Biology, Department of Science, College of Basic Education, Wasit University, Kut, Iraq.
Suyash Saxena
Department of Biochemistry, School of Allied Health Sciences (SSAHS), Sharda University, Greater Noida, Uttar Pradesh, India.
Abdullah Salim Al-Karawi
Department of Microbiology, College of Science, Mustansiriyah University, Baghdad, Iraq.
*Author to whom correspondence should be addressed.
Abstract
Introduction: Chandipura virus (CHPV) causes acute encephalitis syndrome (AES) and is associated with high mortality among children in central and western India. Following the major 2024 outbreak, Gujarat reported a resurgence beginning on 30 June 2026. This study characterised the course of the outbreak and quantified laboratory and mortality indicators with measures of uncertainty.
Methods: Descriptive secondary analysis of aggregated state health bulletins distributed through news services between 21 July and 28 August 2026. Cumulative and interval test positivity (confirmed cases divided by available results) and the crude case fatality rate (CFR) among confirmed cases were calculated with 95% Wilson confidence intervals (CIs).
Results: By 28 August, 324 suspected cases had been reported in Gujarat, of which 42 were confirmed; 28 deaths occurred among confirmed cases (crude CFR 66.7%, 95% CI 51.6-79.0). Cumulative positivity fell from 21.8% (12.9-34.4) to 13.4% (10.1-17.6). Interval positivity fell from 19.5% (13.4-27.6) for 21 July-4 August to 1.5% (0.3-7.9) for 14-28 August, when 67 new suspected cases yielded one new confirmed case. Cases occurred in 12 districts of Gujarat and three of Rajasthan. No vector sample tested positive.
Discussion: Confirmed cases plateaued while suspected case counts continued to rise, suggesting that many current AES cases may not be CHPV infections. Reporting delays, pending results and changes in case definitions cannot be excluded.
Conclusions: This was a severe regional outbreak with a very high crude CFR among confirmed cases. Prompt differential diagnosis, district-level molecular testing and line-listed reporting are required. National burden could not be determined.
Keywords: Chandipura virus, acute encephalitis syndrome, outbreak, Gujarat, RT-PCR, test positivity