PUNE/CHENNAI: A 10-year-old boy, who died on January 31 at Chennai’s Institute of Child Health, has been confirmed as Tamil Nadu’s first Guillain-Barré Syndrome (GBS) victim. His death brings the national toll from the rare but treatable infection to seven since the outbreak began last month.

Pune, which has reported five of the GBS-related deaths, saw its caseload rise by three to reach 166 cases. On Tuesday, the Maharashtra health department identified Campylobacter jejuni as the bacterium responsible for the outbreak, and confirmed that waterborne transmission was likely the primary cause.

“Of the 70 stool samples collected from patients, 27 tested positive for C. jejuni, supporting the hypothesis that contaminated drinking water in the affected areas is responsible for the outbreak,” a senior health official told. “We are confident this is not a foodborne outbreak. If it were, the cases would have followed a distinct pattern, typically linked to a common food source consumed by all victims within the expected incubation period.”

At least 87 cases have been reported within a 5km radius of the suspected contamination zone. “Wells in the affected area draw untreated water from the Khadakwasla dam, which is then directly supplied to the community,” the official added.

Authorities have instructed the water supply department to ensure that all households maintain a minimum chlorine level of 0.2 ppm to prevent further contamination.