PUNE: Civic health authorities investigating the surge in Guillain-Barré Syndrome (GBS) cases in Pune are now checking if lapses in water chlorination in wells caused the diarrhoea spike in areas that reported GBS. Many patients in the city had bouts of diarrhoea days before experiencing GBS symptoms.
The suspect wells include those from where municipal and private tankers drew their water.
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One official said: “While we are yet to confirm a definite failure in water disinfection, discussions with public health experts indicated that even a temporary drop in chlorine levels can lead to bacterial contamination.”
After the GBS surge was reported, civic authorities conducted ‘super-chlorination’ of wells which the official said explained why the bacteria Campylobacter jejuni — a known trigger of GBS — was not detected in water samples tested later by the National Institute of Virology (NIV).
Studies have shown that C. jejuni and norovirus — both found in Pune GBS patients — can also develop chlorine-resistance, which then lets them survive routine disinfection.
“But the super-chlorination likely eradicated them, which is why they weren’t detected in post-surge water testing,” the official added.
Beyond water sources, the health authorities said they are also collecting samples from meat shops located in affected areas. For C. jejuni, poultry is a well-documented reservoir. “The bacteria colonizes intestines of chickens and can spread to humans through contaminated meat, improper handling or cross-contaminated water. We are in the process of analyzing whether this could have played a role in the surge,” said a health department officer.
So far, authorities said C. jejuni has been detected in the stool of five GBS patients; the norovirus has been found in 21 samples.
Investigators are also analysing bacterial and virus clearance rates to check if the “shedding” influenced detection rates. C. jejuni, for instance, leaves the body within a week of infection — people shed it through stool for two to three weeks after symptoms end. And norovirus can leave the body within just three days. However, in rare cases — depending on immunity — both have remained in the body for longer.
“Since C. jejuni was found in five patients and norovirus in 21, we’re now assessing the timing of sample collection to determine if shedding patterns influenced detection rates. Since bacterial and viral shedding varies (some becoming undetectable after a certain period) delayed sampling may have affected results. This exercise is being undertaken to find the definitive trigger; whether it was the bacteria or the virus that was responsible for this surge of Guillain-Barré Syndrome in Pune,” the official said.