Title : Acute gastroenteritis outbreak due to unprotected well water in a village, Tamilnadu, June 2024

Abstract:

Introduction
Around 1 million deaths were due to diarrhoeal diseases globally in 2021. On June 13^th, 2024, Kanchipuram District Government Hospital reported two cases of gastroenteritis to the district surveillance unit. Again 50 cases were reported on June 16^th, 2024. All cases belonged to Vaiyavoor village. We investigated the outbreak to describe it and identify the risk factors.

Methods
We did a cross-sectional study between 18^th June and 30^th June 2024. We defined a case as “Any resident of Vaiyavoor village between the 7^th and 30^th of June with more than 3 stools per day.” We did active surveillance. We collected data on the sociodemographic details, drinking water sources and consumption of food in any festival using a semi-structured questionnaire. We also reviewed the medical records for admission details. We calculated attack rates by age and gender. We drew a spot map and epicurve. We collected one stool sample and tested for salmonella, shigella, and cholera by culture at the Thirupukuzhi Community Centre public laboratory. We collected two water samples, one from common well and one from a tap in Perumal Koil street. We tested for coliform growth by culture at the Guindy Water analysis lab, Chennai. We did an environmental survey for the water source and supply chain in the village.

Results
The population of the Vaiyavoor village was 1093. We identified 60 cases. The overall attack rate was 5%( 60/1093). Attack rate among males and females were 5% (26/549) and 6% (34/544) respectively. Attack rate ranged between 9 and 10 % in the age group 36 to 65 years. Attack rate was lowest in the age group less than 5 years. Spot map showed clustering of cases in Ellaiyamman street {50% (33/60)}. Epicurve showed a point source with a clustering of cases on 13^th and 14^th of June 2024. Cases came down from 16^th and there were no cases after 19^th of June. Among the 60 cases, 19 cases were hospitalised for more than one day (32%) and there were no deaths. There was no growth of any organism in the stool culture. Out of the two water samples, both were positive for coliforms. There were two sources of water supply to the village. Water from an unprotected well was supplied to Ellaiyamman street. Water from the borewell was stored in an overhead tank and supplied to the rest of the streets after chlorination.

Conclusions
The acute gastroenteritis outbreak in Vaiyavoor village was probably due to the unprotected well water. We recommend stopping the use of the well water for drinking purposes. We also recommend regular chlorination of the overhead tank.

Biography:

Dr. P.Velmayil, MPH 15th Cohort, in ICMR, NIE, Ayapakkam, Chennai, Tamil Nadu, India, and graduated as MBBS in 2008 from DR.MGR. Medical University, Chennai. She then joined as a Medical Officer at the Primary Health Centre. She completed Life-saving Anaesthetic Skills Training from the Tertiary Care Center. After one year She worked as Chennai District Epidemiologist for 6 years. She is more interested in public health services. Now doing research and thesis about malnutrition among children.