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Article History

Received: 6 September 2025

Accepted: 23 December 2025

First Online: 13 January 2026

Declarations

:

: Outbreak investigation was carried out with the purpose of identifying the exposure factors and to institute immediate control measures to prevent morbidity and mortality as part of the public health response of Uttar Pradesh State Health Department and National Centre for Disease Control (NCDC), India. Ethical approval was not applicable as the investigation was conducted as part of public health response and consistent with applicable state and central government law (Epidemic Diseases Act no.3, 1897). The investigation did not involve any sample collection for research or intervention. Only observational investigation was conducted as required for outbreak control, and hence, this investigation was considered non-research public health activity. Informed consent was obtained from all individual respondents in the cohort (cases and non-cases). Data protection protocols as per NCDC, ethical principles and guidelines by the Government of India, and the 1964 Helsinki Declaration and its later amendments or comparable ethical standards were followed during public health response. All respondents were interviewed after obtaining informed consent.

: Not applicable as no identifiable individual case details are mentioned.

: The authors declare no competing interests.