Pune GBS Outbreak That Killed 12 Linked to Two Pathogens: NIV Study

Pune, 22nd October 2026: A study by the National Institute of Virology (NIV) has linked infections caused by Campylobacter jejuni bacteria and norovirus to the Guillain-Barré Syndrome (GBS) outbreak in Pune last year, which affected 230 people and claimed 12 lives between January and March 2025.

Researchers tested samples from patients, water sources and chicken droppings to investigate the possible causes of the outbreak. The findings identified both infectious agents, pointing to the need for further research to establish how they contributed to the outbreak.

The study suggests that multiple infectious agents may have been involved, with Campylobacter jejuni emerging as a major contributor and norovirus also playing a significant role. The detection of these pathogens in water and chicken droppings provided clues about possible sources of infection. However, the findings do not establish contaminated water or poultry as the definitive source of the outbreak.

Of the 230 patients investigated, 147 (63.9%) had experienced another infection before developing GBS symptoms. Diarrhoea was the most common preceding symptom, reported in about 37% of patients, indicating a possible link between gastrointestinal infections and the outbreak.

The outbreak affected people across all age groups, with the number of male patients 2.2 times that of female patients. The Sinhagad Road area reported the highest concentration of cases.

Among 193 patients tested, 108 (56%) showed evidence of an infectious agent. Of the 148 patient samples tested for Campylobacter jejuni, 72 (48.7%) tested positive for the bacterium.

Norovirus was detected in 40 of the 180 patient samples tested. Of these, 21 patients had only norovirus infection, while 19 had norovirus alongside another infection.

Researchers also examined 208 water samples, detecting Campylobacter in one sample and norovirus in eight. Of the 66 chicken-dropping samples tested, 24 were positive for Campylobacter, while five contained norovirus.

No evidence of toxic substances was found in nine selected water samples tested as part of the investigation.