Shigella Outbreak

Shigella Outbreak News

Update #1 Date- 30/06/2026

Occurrence Update

Kerala has reported an increase in Shigella infections during June 2026, prompting enhanced surveillance and public health response across multiple districts. The outbreak has predominantly affected school-aged children and household contacts, with epidemiological investigations indicating transmission through contaminated food and water, poor sanitation, and person-to-person contact.

Shigellosis remains an important public health concern because of its high infectivity, low infectious dose, and increasing antimicrobial resistance (AMR).

The outbreak was first recognized following clusters of acute gastroenteritis among school children and community members in early June 2026. Cases increased progressively during the month, with continued reports of community transmission.

According to the latest available reports:

  • Approximately 290 laboratory-confirmed cases have been reported in Kerala during June 2026.
  • Six deaths have been associated with the outbreak.
  • Cases continue to be reported from multiple districts, indicating ongoing local transmission.
  • Enhanced surveillance and outbreak investigation activities remain in progress.

The highest number of reported cases has been recorded from:

  • Kozhikode
  • Wayanad
  • Malappuram
  • Thrissur
  • Ernakulam
  • Kollam
  • Thiruvananthapuram

Kozhikode continues to report the highest disease burden and remains under intensified surveillance.

Causative Agent

Shigellosis is caused by Gram-negative bacteria belonging to the genus Shigella, comprising four species:

  • Shigella sonnei
  • Shigella flexneri
  • Shigella dysenteriae
  • Shigella boydii

Shigella is among the leading bacterial causes of diarrhoeal disease globally and is responsible for substantial morbidity and mortality, particularly among children younger than five years in low- and middle-income countries.

Increasing multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains represent an emerging global public health threat.

Mode of Transmission

Shigella is transmitted primarily through the faecal–oral route.

Transmission occurs through:

  • Consumption of contaminated food
  • Consumption of contaminated drinking water
  • Poor hand hygiene
  • Direct person-to-person contact
  • Contact with contaminated household surfaces or fomites
  • Exposure in schools, childcare centres, healthcare facilities, and other crowded settings
  • Food prepared by infected food handlers

Because the infectious dose is extremely low, approximately 10–100 bacteria, secondary household and institutional transmission can occur readily.

Clinical Features

The incubation period is typically 1–3 days, with a possible range of 12 hours to 7 days.

Common clinical manifestations include:

  • Acute diarrhoea
  • Bloody or mucus-containing diarrhoea, also known as dysentery
  • Fever
  • Abdominal cramps
  • Tenesmus
  • Nausea
  • Vomiting
  • Fatigue
  • Dehydration

Most patients recover within 5–7 days. However, severe illness may occur among young children, older adults, malnourished individuals, and immunocompromised persons.

Possible complications include severe dehydration, electrolyte imbalance, seizures, toxic megacolon, haemolytic uraemic syndrome, and bloodstream infection.

Diagnosis

Laboratory confirmation is based on:

  • Stool culture, which is considered the reference standard
  • Stool PCR or multiplex molecular assays
  • Antimicrobial susceptibility testing
  • Microscopic examination of stool specimens

WHO recommends antimicrobial susceptibility testing wherever feasible because of the increasing prevalence of antimicrobial-resistant Shigella strains.

Treatment

Management is primarily supportive and includes:

  • Oral Rehydration Solution (ORS)
  • Intravenous fluid therapy for severe dehydration
  • Antibiotic therapy guided by antimicrobial susceptibility testing and national treatment guidelines
  • Zinc supplementation for eligible children
  • Nutritional support
  • Electrolyte replacement

Appropriate antimicrobial stewardship is essential to limit the emergence and spread of resistant Shigella strains.

Public Health Response

The Kerala Department of Health has implemented comprehensive outbreak response measures, including:

  • Enhanced surveillance through the Integrated Disease Surveillance Programme (IDSP)
  • Rapid identification and laboratory confirmation of suspected cases
  • Active case finding and contact tracing
  • Monitoring of school-based clusters
  • Water quality surveillance and chlorination
  • Food safety inspections
  • Infection prevention and control (IPC) measures
  • Community awareness and risk communication
  • Health education on hygiene and sanitation

Prevention and Control Measures

WHO and CDC recommend the following preventive measures:

  • Wash hands thoroughly with soap and clean water after using the toilet and before preparing or eating food.
  • Drink boiled, filtered, or otherwise treated water.
  • Consume freshly prepared and thoroughly cooked food.
  • Wash fruits and vegetables with safe water.
  • Maintain adequate sanitation and safe disposal of human waste.
  • Avoid open defecation.
  • Exclude symptomatic individuals from food preparation until at least 48 hours after diarrhoea has resolved.
  • Clean and disinfect frequently touched household surfaces.
  • Promote hygiene education in schools and childcare settings.
  • Seek prompt medical care for persistent diarrhoea, bloody stools, fever, or signs of dehydration.

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Last Updated on: 06-07-2026

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