Investigation of an acute diarrheal disease outbreak in a municipality in southwestern Bahia: Experience report
1
Health Surveillance Superintendence (SUVISA), Southwest Regional Health Center (NRS-SO), Bahia State Health Department (SESAB), Guanambi, Brazil
2
Languages and Literature, UniCesumar University, Guanambi, Brazil
3
Southwest Regional Health Center (NRS-O), Bahia State Health Department (SESAB), Guanambi, Brazil
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
Between October 20 and November 4, 2024, a municipality in southwestern Bahia, Brazil, reported an outbreak of acute diarrheal disease (ADD). The event raised concerns about drinking-water safety and the effectiveness of control measures. This experience reports the investigation, identification of contributing factors and proposed corrective actions.
METHODS:
The Bahia State Health Department, through the Center for Strategic Information on Health Surveillance (CIEVS, in Portuguese) and the Southwestern Regional Health Center (NRS Sudoeste), conducted an on-site investigation at the local Water Treatment Plant (WTP). Structural and operational failures were assessed. Water and stool samples were collected, although low community adherence limited laboratory analysis. Data inconsistencies were examined using the Acute Diarrheal Disease Epidemiological Surveillance System (SIVEP-DDA, in Portuguese). The team evaluated treatment efficiency, residual chlorine levels and distribution-system performance. Corrective actions and risk-communication measures were recommended to local authorities.
RESULTS:
Water analysis showed contamination by total coliforms and pathogens such as Chromobacterium violaceum, Bacillus cereus and Aeromonas spp., indicating inefficiency in the WTP process. One stool sample tested positive for Rotavirus. The outbreak involved 894 to 1,340 notified cases, but inconsistencies in SIVEP-DDA revealed weaknesses in reporting. Failures such as absence of residual chlorine, inadequate infrastructure and operational gaps were associated with the event. Low participation in sample collection limited clinical investigation. Epidemiological and environmental evidence indicated that water contamination was the main factor contributing to the ADD outbreak.
CONCLUSIONS:
The outbreak was linked to failures in water treatment and distribution. Recommendations included structural improvements to the WTP, restoration of residual chlorine, temporary suspension of water consumption until corrections were completed, distribution of household bleach, public guidance on safe water treatment and reinforcement of epidemiological surveillance. A rapid and coordinated response is essential to prevent worsening of cases and ensure safe drinking water for the population.
Between October 20 and November 4, 2024, a municipality in southwestern Bahia, Brazil, reported an outbreak of acute diarrheal disease (ADD). The event raised concerns about drinking-water safety and the effectiveness of control measures. This experience reports the investigation, identification of contributing factors and proposed corrective actions.
METHODS:
The Bahia State Health Department, through the Center for Strategic Information on Health Surveillance (CIEVS, in Portuguese) and the Southwestern Regional Health Center (NRS Sudoeste), conducted an on-site investigation at the local Water Treatment Plant (WTP). Structural and operational failures were assessed. Water and stool samples were collected, although low community adherence limited laboratory analysis. Data inconsistencies were examined using the Acute Diarrheal Disease Epidemiological Surveillance System (SIVEP-DDA, in Portuguese). The team evaluated treatment efficiency, residual chlorine levels and distribution-system performance. Corrective actions and risk-communication measures were recommended to local authorities.
RESULTS:
Water analysis showed contamination by total coliforms and pathogens such as Chromobacterium violaceum, Bacillus cereus and Aeromonas spp., indicating inefficiency in the WTP process. One stool sample tested positive for Rotavirus. The outbreak involved 894 to 1,340 notified cases, but inconsistencies in SIVEP-DDA revealed weaknesses in reporting. Failures such as absence of residual chlorine, inadequate infrastructure and operational gaps were associated with the event. Low participation in sample collection limited clinical investigation. Epidemiological and environmental evidence indicated that water contamination was the main factor contributing to the ADD outbreak.
CONCLUSIONS:
The outbreak was linked to failures in water treatment and distribution. Recommendations included structural improvements to the WTP, restoration of residual chlorine, temporary suspension of water consumption until corrections were completed, distribution of household bleach, public guidance on safe water treatment and reinforcement of epidemiological surveillance. A rapid and coordinated response is essential to prevent worsening of cases and ensure safe drinking water for the population.
| eISSN: | 2654-1459 |
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