As we navigate the complexities of a post-pandemic world, whispers of emerging and resurging diseases have begun to echo across global health discussions. From mysterious, unnamed threats to the resurgence of once-controlled infections, scientists and medical professionals are raising the alarm. These diseases are not confined to distant regions; their potential to disrupt lives and overwhelm healthcare systems could impact us all.
What are these looming threats, and why are they gaining attention now? How have factors like climate change, antibiotic resistance, and global interconnectedness heightened their risk? This article uncovers the most concerning diseases of 2025—some familiar, others unexpected—offering insights into the challenges ahead and what they mean for our collective future.
Antimicrobial-Resistant Bacteria
Antimicrobial resistance (AMR) is an escalating global health crisis, with bacteria evolving to withstand treatments that once eradicated them. The World Health Organization (WHO) has labeled AMR a top global health threat, noting that it compromises our ability to treat infections and control public health threats.
In 2019, drug-resistant bacterial infections were linked to approximately 1.27 million deaths worldwide.
The Centers for Disease Control and Prevention (CDC) reports that in the United States, more than 2.8 million antimicrobial-resistant infections occur each year, resulting in over 35,000 deaths.
The WHO has developed strategic and operational priorities to address drug-resistant bacterial infections in the human health sector for 2025–2035, emphasizing the need for a concerted national and global response. Additionally, global leaders have committed to reducing the estimated 4.95 million human deaths associated with bacterial AMR annually by 10% by 2030.
UK Health Security Agency Chief Executive Professor Dame Jenny Harries emphasizes the importance of responsible antibiotic use: “Only take antibiotics if you have been told to do so by a healthcare professional. Do not save some for later or share them with friends and family. This isn’t just for your own health—it’s about protecting everyone in our communities and future generations.”
To combat this threat, the WHO supports the Global Antibiotic Research & Development Partnership (GARDP), aiming to develop five new treatments by 2025 to fight drug-resistant infections.
Bird Flu (Avian Influenza)
Avian influenza, commonly known as bird flu, is an infectious disease primarily affecting bird species but with the potential to infect humans. The H5N1 strain, in particular, has been a significant concern due to its high mortality rate in humans and its ability to infect a broad range of hosts.
Recent studies have revealed that horses can carry the H5N1 virus without exhibiting symptoms, raising concerns about undetected transmission pathways. Researchers from the University of Glasgow found antibodies against H5N1 in Mongolian horses, suggesting asymptomatic infections. This asymptomatic carriage could facilitate the virus’s spread to humans, especially in regions where humans and horses interact closely.
In the United States, the first bird flu-related death was reported in Louisiana. The patient, over 65 with underlying health conditions, contracted the H5N1 virus through exposure to backyard chickens and wild birds. This case underscores the virus’s potential severity and the importance of monitoring zoonotic transmissions.
Dr. Michael Head, Senior Research Fellow in Global Health at the University of Southampton, emphasizes the pandemic potential of avian influenza: “A permanent member of any ‘possible infectious disease threat’ list, avian influenza evolves its shape and style a little like the Covid variants, and has the potential to cause a pandemic. We haven’t yet seen widespread human-to-human transmission—but we could do.”
Chikungunya
Chikungunya is a mosquito-borne viral disease primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes. The disease is characterized by sudden onset of fever and severe joint pain, often debilitating, with symptoms typically appearing 4 to 8 days after a mosquito bite. Other common symptoms include muscle pain, headache, nausea, fatigue, and rash. While most patients recover fully, joint pain can persist for months or even years in some cases.
In 2024, chikungunya continued to pose a significant global health challenge. As of November 30, approximately 480,000 cases and over 200 deaths were reported worldwide, with 23 countries across the Americas, Asia, Africa, and Europe affected.
The economic impact of chikungunya is substantial. Over the past decade, an estimated 18.7 million cases have resulted in 1.95 million disability-adjusted life years (DALYs) lost, with the Latin American and Caribbean regions bearing the highest burden.
Recent studies have highlighted the potential for chikungunya to cause chronic arthritis. Experts note that “chikungunya triggers lifelong arthritis in 13% of total patients,” underscoring the need for effective treatment and management strategies.
Efforts to combat chikungunya include vaccine development. In May 2024, the European Medicines Agency recommended the use of Valneva’s single-shot chikungunya vaccine, VLA1553, for adults. If approved by the European Commission, this would be the first preventive vaccine for chikungunya in Europe. The vaccine has already been approved in the U.S., where it is sold under the brand name Ixchiq. During late-stage trials, VLA1553 was shown to induce antibody levels capable of neutralizing the virus in 98.9% of participants 28 days after vaccination.
Additionally, scientists have launched the largest-ever study tracking chikungunya’s burden in East Africa. Led by the University of Oxford, this research aims to investigate the number of children and adults affected by the disease in Kenya and Tanzania, providing crucial data to inform public health strategies.
Cholera
Cholera is an acute diarrheal infection caused by ingesting food or water contaminated with the bacterium Vibrio cholerae. It remains a global threat to public health, particularly in regions with inadequate sanitation and limited access to clean water.
The World Health Organization (WHO) estimates that annually, there are between 1.3 to 4.0 million cases of cholera worldwide, resulting in 21,000 to 143,000 deaths.
Recent years have seen a resurgence of cholera outbreaks. In 2024, 28 countries across five WHO regions reported a cumulative total of 371,517 cholera cases and 2,527 deaths by August.
Factors such as conflict, mass displacement, natural disasters, and climate change have intensified outbreaks, particularly in rural and flood-affected areas, where poor infrastructure and limited healthcare access delay treatment.
The global stockpile of Oral Cholera Vaccines (OCV) has faced critical shortages, with demand outpacing supply. In November 2024, OCV production reached its highest level since 2013, driven by new formulations, yet challenges persist in meeting global needs.
Efforts to combat cholera include the Global Task Force on Cholera Control’s (GTFCC) “Roadmap 2030,” aiming to reduce cholera deaths by 90% and eliminate the disease in 20 countries by 2030.
Covid
COVID-19, first identified in late 2019, continues to significantly impact global health as of January 2025. The virus has evolved into multiple variants, with the Omicron subvariant XEC recently becoming predominant. XEC is a recombinant strain, merging genetic material from two previous Omicron sublineages, KP.3.3 and KS.1.1, which has led to increased transmissibility.
Despite the increased spread of XEC, current vaccines remain effective in preventing severe illness, hospitalization, and death. Health authorities, including the Centers for Disease Control and Prevention (CDC), recommend that everyone aged six months and older receive the updated 2024–2025 COVID-19 vaccine to maintain immunity.
Ongoing research continues to monitor the virus’s evolution and the effectiveness of vaccines. The Joint Committee on Vaccination and Immunisation (JCVI) has resumed standard cost-effectiveness assessments for COVID-19 vaccination, aligning with other routine vaccinations in the national immunisation programme.
Dengue
Dengue fever, a mosquito-borne viral infection, has seen a significant global surge in recent years. As of April 30, 2024, over 7.6 million cases were reported to the World Health Organization (WHO), including more than 3,000 deaths.
This alarming increase is particularly pronounced in the Region of the Americas, where cases have already exceeded seven million, surpassing the annual high of 4.6 million cases in 2023.
In response to this escalating health crisis, advancements in vaccine development have been made. On May 10, 2024, WHO prequalified a new dengue vaccine, TAK-003, developed by Takeda. This live-attenuated vaccine contains weakened versions of the four serotypes of the virus that cause dengue. WHO recommends its use in children aged 6–16 years in settings with high dengue burden and transmission intensity, administered in a two-dose schedule with a three-month interval between doses.
Despite these developments, challenges remain. The unprecedented global upsurge in dengue cases poses a major public health challenge, necessitating enhanced surveillance, vector control measures, and public awareness to effectively combat the spread of the disease.
Disease X
In 2018, the World Health Organization (WHO) introduced the term “Disease X” as a placeholder for an unknown pathogen that could cause a future epidemic or pandemic. This concept underscores the necessity for flexible and comprehensive preparedness strategies to address unforeseen health threats.
The emergence of COVID-19 exemplified the reality of Disease X, highlighting global vulnerabilities to novel pathogens. In response, WHO has emphasized the importance of adaptable research and development frameworks. Dr. Anthony Fauci noted that the Disease X concept encourages focusing on entire classes of viruses, enhancing the ability to respond to unforeseen strains.
Recent events, such as the outbreak in the Democratic Republic of the Congo in December 2024, where an unidentified disease infected over 400 people and resulted in at least 79 deaths, further illustrate the potential impact of unknown pathogens. This situation was initially referred to as Disease X until it was identified as an aggressive strain of malaria.
Measles
Measles, a highly contagious viral disease, has seen a troubling resurgence in recent years, largely due to declining vaccination rates. The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) reported a 20% increase in global measles cases from 2022 to 2023, with numbers rising from approximately 8.6 million to 10.3 million cases.
This resurgence is attributed to a decline in vaccination coverage. First-dose measles-containing vaccine coverage dropped from 86% in 2019 to 81% in 2021 during the COVID-19 pandemic, the lowest reported level since 2008.
The consequences of reduced vaccination are evident in various regions. In Europe, there was an “alarming” nearly 45-fold increase in measles cases in 2023 compared to 2022.
Similarly, the United Kingdom’s Health Security Agency declared a “national incident” in January 2024 after suspected measles cases more than quadrupled in England and Wales, rising from 360 in 2021 to 1,603 in 2023.
In Australia, health authorities have issued warnings about significant measles outbreaks in Southeast Asia, particularly in Vietnam and Thailand. Travelers are urged to ensure they have received the measles-mumps-rubella (MMR) vaccine before traveling to these regions.
Scabies
Scabies, a highly contagious skin infestation caused by the mite Sarcoptes scabiei, has seen a notable resurgence in the UK. The British Association of Dermatologists reports that the incidence rate has risen to approximately three cases per 100,000 people, compared to the historical average of one case per 100,000 over the past five years.
This increase is particularly evident in the north of England, where the weekly incidence rate is about five cases per 100,000 population.
Scabies is transmitted through close physical contact, including sexual activity, and can spread rapidly in communal settings such as care homes, hospitals, and schools. The primary symptom is intense itching, especially at night, accompanied by a rash of small red spots. Commonly affected areas include the hands, wrists, elbows, and buttocks.
The standard treatment involves topical scabicides like permethrin 5% cream, applied to the entire body and repeated after seven days to ensure all mites and eggs are eradicated. Oral ivermectin is also available in the UK for scabies treatment, typically administered as a single dose with food, with the dosage based on body weight.
In light of the recent surge in cases, health professionals emphasize the importance of early diagnosis and treatment to prevent further transmission. The UK Health Security Agency advises that all close contacts of an infected individual should be treated simultaneously, even if asymptomatic, to effectively control outbreaks.
Whooping Cough (Pertussis)
Whooping cough, or pertussis, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It is characterized by severe coughing fits that can be particularly dangerous for infants and young children. The disease spreads through respiratory droplets when an infected person coughs or sneezes.
In 2024, there has been a significant resurgence of whooping cough cases globally. For instance, Australia is experiencing its largest epidemic since the introduction of vaccines, with over 41,000 cases reported, surpassing the previous record of 38,748 cases in 2011. This alarming increase is attributed to factors such as declining vaccination rates and the aftermath of COVID-19 restrictions.
Similarly, the United States has observed a return to pre-pandemic levels, with more than 10,000 cases typically reported each year. The Centers for Disease Control and Prevention (CDC) notes that mitigation measures during the COVID-19 pandemic, like masking and remote learning, likely lowered transmission of pertussis temporarily.
Infants under six months, who are unimmunized or partially immunized, face the highest risk of severe outcomes. The majority of pertussis-related hospitalizations and deaths occur in this vulnerable age group.
Vaccination remains the most effective method to prevent whooping cough. However, vaccination rates have declined in recent years. In Australia, one in four adolescents missed their booster by age 13, and only one in five people over 50 are up-to-date. Health authorities emphasize the importance of booster shots every 10 years to maintain immunity.
In the United States, the CDC recommends that pregnant women in their last trimester and family members or caregivers of infants receive the tetanus, diphtheria, and pertussis (Tdap) vaccine to protect newborns from pertussis.
West Nile Fever
West Nile Fever, caused by the West Nile Virus (WNV), is a mosquito-borne disease that has seen a notable increase in cases across Europe in recent years. The virus is primarily transmitted to humans through the bites of infected mosquitoes, with migratory birds often serving as reservoirs.
In the 2024 transmission season, as of December 4, 2024, 19 countries in Europe have reported 1,436 locally acquired human cases of WNV infection. The countries with the highest reported cases include Italy (455), Greece (217), Spain (138), and Hungary (111).
This upward trend is concerning, especially considering that in the 2023 season, there were 728 human cases reported, indicating a significant rise in infections within a year.
Approximately 80% of WNV infections in humans are asymptomatic, about 20% may develop West Nile Fever (WNF). Less than 1% of infected individuals may develop severe neurological diseases, such as encephalitis or meningitis, which can be fatal.
Preventative Measures Against Emerging Diseases
As global health threats evolve, preventative measures play a crucial role in safeguarding individuals and communities from outbreaks. While each disease may have specific strategies, there are universal preventive actions that can significantly reduce the risk of transmission and impact.
1. Vaccination: Vaccination remains the most effective tool against many diseases like measles, whooping cough, and COVID-19. Ensure routine immunizations are up-to-date, including booster doses where required. Stay informed about new vaccines, such as those for dengue and chikungunya, which offer targeted protection in high-risk areas.
2. Mosquito Control: Use insect repellents containing DEET or picaridin. Install window and door screens to prevent mosquitoes from entering homes. Eliminate standing water in and around living spaces to reduce mosquito breeding.
3. Hygiene and Sanitation: Regularly wash hands with soap and clean drinking water. Ensure food is cooked thoroughly and water is treated or boiled. Avoid sharing personal items and maintain clean bedding and clothing to prevent infestations.
4. Antibiotic Stewardship: Only take antibiotics as prescribed by healthcare professionals. Avoid sharing or saving leftover antibiotics for future use. Advocate for policies promoting responsible antibiotic use in agriculture and healthcare.
5. Surveillance and Early Detection: Public health surveillance systems play a critical role in early disease detection and containment. Support local and global health initiatives that track emerging pathogens, such as Disease X, to ensure rapid response.
6. Public Awareness and Education: Education campaigns can help individuals recognize early symptoms of diseases and seek timely medical intervention. Promote community-level efforts to reduce stigma around reporting symptoms and accessing healthcare.
7. Travel Precautions: When traveling to high-risk regions, consult a healthcare provider for recommended vaccinations and prophylactic treatments. Avoid contact with animals in areas experiencing outbreaks, such as during bird flu events. Follow travel advisories and guidelines provided by global health organizations.
8. Strengthening Immunity: Maintain a balanced diet rich in vitamins and minerals. Exercise regularly and manage stress. Get adequate sleep to support overall health.
9. Climate and Environmental Considerations: Advocate for policies addressing environmental issues contributing to disease proliferation. Support sustainable practices to mitigate the effects of climate change on global health.
10. Global Collaboration: Support initiatives like the WHO’s Global Task Force on Cholera Control and partnerships aimed at developing vaccines and treatments for emerging diseases. Encourage equitable distribution of resources, including vaccines and medical supplies, to ensure global preparedness.
Uniting for a Disease-Free Future
As we look toward 2025, the emergence and resurgence of dangerous diseases highlight the delicate balance of global health. From the rise of antimicrobial-resistant bacteria to the lurking potential of Disease X, the need for vigilance, scientific innovation, and collaborative efforts has never been more urgent. The battle against these health threats requires a collective commitment to prevention, awareness, and equitable access to healthcare.
By embracing preventative measures, supporting vaccination programs, and addressing environmental challenges, we can reduce the impact of these diseases and safeguard communities worldwide. The challenges are significant, but with proactive strategies and unified action, we can build a healthier and more resilient future.
