In Nigeria’s central Plateau State, an outbreak has claimed 31 lives, with 469 suspected cases recorded across 10 local government areas. State health officials stated that the situation became a major public health concern in August, following sporadic cases earlier in the year. The local government area of Jos North accounted for the majority of suspected cases, with 370 individuals affected. In response, the state government activated its Incident Management System and has vaccinated over 160,000 children with diphtheria and tetanus vaccines. However, authorities acknowledge a shortfall of approximately 250,000 doses needed to fully cover the remaining at-risk populations in affected areas.
Simultaneously, Australia is grappling with its largest diphtheria outbreak since 1991. Since January, the country has recorded more than 220 cases, with the Northern Territory bearing the highest burden. In March, the Northern Territory declared an official outbreak, and in April, a man’s death at Royal Darwin Hospital was confirmed via autopsy as being caused by diphtheria, marking the first such fatality in the state since 2018. Western Australia has also expanded its response, reporting 170 cases predominantly among Aboriginal people in the Kimberley, Pilbara, and Goldfields regions. Of these, 104 were cutaneous (skin) infections and 66 were respiratory infections, including two severe respiratory cases. The Australian federal government has announced a 7.2 million AUD emergency support package to boost vaccination rates and strengthen the health workforce in affected states.
Experts attribute the Australian outbreak to waning immunity, lower routine immunization rates, and higher prevalence of skin infections in remote communities. Approximately 94% of cases identified since January have been among Aboriginal and/or Torres Strait Islander people. While most cases involve cutaneous diphtheria, which causes slow-healing ulcers, respiratory diphtheria remains the more pressing public health concern. This form affects the throat and airways, producing a thick gray membrane that can obstruct breathing. Even with treatment, up to 10% of people with respiratory diphtheria die from complications affecting the heart and nervous system.
The pattern of resurgence is mirrored in the Americas. The Pan American Health Organization (PAHO) reported 163 confirmed cases in the first 21 weeks of 2026, more than double the number reported in the same period in 2025. Haiti accounted for the vast majority of these infections, with 159 cases and all five reported deaths in the region. PAHO noted that more than half of the confirmed cases occurred among individuals who were unvaccinated or had unknown vaccination status. Regional vaccination coverage for the third dose of the diphtheria, tetanus, and pertussis (DTP3) vaccine declined to 87% in 2024, falling well below the 95% target required to provide community protection.
Prevention and Response Strategies
Diphtheria, caused by the bacterium Corynebacterium diphtheriae, spreads through respiratory droplets and close contact with infected skin sores. Health authorities in all affected regions are emphasizing that vaccination is the most critical measure for preventing severe illness and reducing transmission. In Australia, pop-up clinics have been established in Darwin, Katherine, and Alice Springs to administer boosters to teenagers and adults who have not received a diphtheria-containing vaccine in the past five years. In Nigeria, community sensitization efforts include training school teachers to identify early symptoms and facilitate appropriate medical responses.
PAHO has urged countries in the Americas to close vaccination gaps by reinforcing routine immunization programs and implementing catch-up strategies. The organization recommends that health systems use every patient contact to verify vaccination status and complete immunization schedules. Additionally, authorities are advised to maintain adequate supplies of diphtheria antitoxin and ensure rapid laboratory confirmation of suspected cases.
While the outbreaks present serious public health challenges, officials in Australia indicate that new case numbers are beginning to fall following intensified vaccination efforts. In Nigeria, mild cases are being managed within communities, while severe cases are being isolated and treated at specialist hospitals. The global rise in cases serves as a stark reminder that diphtheria, though rare in highly vaccinated populations, can re-emerge rapidly when coverage drops below critical thresholds. Continued surveillance, equitable vaccine access, and high community immunity remain essential to controlling further spread.
