Work

Epidemiological investigation and public health response to a diphtheria outbreak in Jalalabad Union, Sylhet, December 2023

Year: 2025

Type: article

Abstract: • C. diphtheriae causes diphtheria via close contact/respiratory droplets • 2010–2022: 112,157 global cases (69,060 in SEARO); Bangladesh reports sporadic cases despite high EPI coverage • Sylhet, 2023: three PCR-confirmed cases (all vaccinated); 27 close contacts investigated; ring vaccination, chemoprophylaxis, community education implemented • Source undetermined; asymptomatic carriage and waning immunity in older children likely contributors; DAT scarcity constrained care • Implications: introduce/strengthen booster doses beyond EPI, maintain DAT stockpiles, and ensure antibody titre in future outbreak response. : Diphtheria incidence has significantly declined globally due to the Expanded Program on Immunization, yet breakthrough infections occur due to waning immunity in late childhood. Since 2010, Bangladesh has reported 148 cases. On 10 December 2023, a suspected diphtheria case was reported to the Institute of Epidemiology, Disease Control and Research (IEDCR), prompting an epidemiological investigation and public health response. : Following WHO guidelines, the team identified suspected and confirmed cases, conducted interviews with the index case and contacts, and collected samples for polymerase chain reaction (PCR) testing. Risk communication and active case searches were carried out in the affected area. : The index case, a 10-year-old girl with classic diphtheria symptoms, was hospitalized for 15 days and recovered after receiving antibiotics and diphtheria antitoxin (DAT). Among 25 close contacts, 14 (56%) were suspected cases, and 2 (8%) were confirmed via PCR: these 2 positive cases were siblings of the index case and previously vaccinated. Chemoprophylaxis, vaccination, isolation, and quarantine were implemented, although two later confirmed cases, did not receive DAT due to unavailability. : Despite a high average coverage rate of 95% (2018-2022) of Penta 3, the outbreak revealed potential waning immunity or vaccine failure. The outbreak was effectively contained through timely confirmation, contact tracing, prophylactic antibiotics given, immunization, and quarantine. Booster doses, quantifying antibody titer, and DAT access remain critical.

Source: IJID Regions

DOI: 10.1016/j.ijregi.2025.100805