Among the diseases making a troubling comeback are tuberculosis, plague, Lassa fever, yellow fever, measles, cholera, malaria, typhoid fever, influenza, dengue fever, Staph infections, and diphtheria. The WHO attributes this resurgence to a confluence of factors, including reduced vaccination rates, the pervasive issue of antimicrobial resistance (AMR), and profound climate and environmental changes. The organization strongly reiterates that immunization and vaccination remain the most critical tools for curbing the infection and spread of these communicable diseases.
Diphtheria: A Deadly Resurgence
Diphtheria, a deadly disease previously brought under global control (with an over 80% decrease in burden between 1980 and 2018), has tragically re-emerged in various parts of the world. The WHO African Region is currently battling a significant resurgence, with five active outbreaks reported in Guinea, Mauritania, Niger, Nigeria, and South Africa. Caused by Corynebacterium diphtheriae, a bacterium transmitted through respiratory droplets, close physical contact, and contaminated objects, diphtheria can cause severe toxic damage to vital organs like the heart, kidneys, and peripheral nerves.
In Nigeria, the Centre for Disease Control and Prevention (NCDC) reported a grim picture between February and March 2025: 42,642 suspected cases and 25,812 confirmed cases across the country, resulting in 1,319 recorded deaths.
Tuberculosis: A Persistent and Drug-Resistant Threat
Tuberculosis (TB) is another re-emerging disease. Europe alone reported over 225,000 cases in 2023 and 16,000 fatalities, as highlighted in the 2025 European Tuberculosis Surveillance Report. Alarmingly, 30% of cases in the 53 WHO European Region member states that reported TB were drug-resistant. The world’s top 30 countries with a high burden of drug-resistant tuberculosis are also located in the European Region, with over 53% of Europe's drug-resistant cases occurring in previously treated patients.
In the USA, an outbreak early in 2025 saw 147 reported cases and two fatalities. The United States CDC confirmed that Mycobacterium tuberculosis, the bacterium causing TB, has developed multi-drug resistant strains, leading the WHO to re-add it to the global list of critical pathogens.
Measles: A Highly Contagious Comeback
Measles, a highly contagious airborne disease, has also made a forceful comeback. As of March 2025, 57 countries reported measles outbreaks, including Morocco, DR Congo, Canada, and the USA. In Morocco, over 25,000 cases were reported from October 2023 to April 2025, leading to 184 deaths, with 68% of cases affecting individuals under 18. DR Congo reported approximately 2,000 cases with 180 fatalities.
Even the US, which declared measles eliminated in 2000, is facing an outbreak. Dr. Dan Filardo, Head of the Measles Task Force at the US CDC, reported 1,001 confirmed cases as of May 11, 2025. Resurgences have also been noted in Canada with around 1,000 cases and Mexico with over 400 cases.
Other Alarming Trends
The resurgence of meningitis, an inflammation of the tissues surrounding the brain and spinal cord, is also a growing concern. Sub-Saharan African countries, including Nigeria, are particularly vulnerable, and while the WHO initially reported a decline, a significant increase in cases has recently been observed, alongside rising meningococcal disease cases in the USA.
Cholera, a water-borne infection causing severe diarrhea and vomiting, has seen a dramatic rise, particularly in Eastern and Southern Africa. The WHO reports that since 2023, the region has been battling its worst cholera epidemic, affecting 13 countries with over 200,000 cases and 3,000 deaths. Zambia recorded over 9,500 cases and 374 deaths, with a 3.9% case fatality rate and 52% of cases affecting children. Zimbabwe reported over 18,000 cases, with one in six new infections affecting children under five. Etleva Kadilli, UNICEF Regional Director for Eastern and Southern Africa, highlighted the severe impact on children and the exacerbating role of climate change, worsened by phenomena like El Niño.
The increasing prevalence of antimicrobial resistance makes treating these infectious diseases increasingly challenging. Coupled with the escalating disruption of ecosystems due to climate change, containing the spread of these diseases during outbreaks has become an arduous task. Therefore, the WHO's emphasis on prevention through vaccination stands as the most effective and critical strategy to control these re-emerging communicable diseases and safeguard global health.