If there is one lesson COVID taught us, it is the profound impact diseases and viruses can have on our daily lives. Every day, we face the return of infections that were once under control, as well as the emergence of new, previously unknown threats. As we’ve learned, these diseases don’t just affect distant regions of the world; they can reach much closer to home. In this article, we will explore the 11 deadliest diseases currently threatening humanity.
Bird Flu
Bird flu doesn’t only affect birds; it can also infect various other species, including humans. Researchers have even found asymptomatic cases in horses, raising concerns about the hidden transmission of the virus. The first death in the U.S. was linked to exposure to poultry in Louisiana. Although widespread human-to-human transmission has not occurred yet, the virus still holds the potential to escalate into a pandemic.
Antimicrobial-Resistant Bacteria
Antimicrobial resistance (AMR) is an escalating global crisis. Drug-resistant infections claim 1.27 million lives every year. Both the WHO and CDC have raised alarms about the growing threat AMR poses to public health. They have called for responsible antibiotic use and global cooperation. Efforts to tackle this issue include a goal to reduce AMR-related deaths by 10% by 2030, along with the development of five new treatments by 2025 through the Global Antibiotic Research & Development Partnership.
Cholera
Cholera remains a serious global health challenge, caused by contaminated food or water. It continues to infect millions, with up to 4 million cases reported annually. In 2024 alone, 28 countries reported 371,517 cases, resulting in 2,527 deaths. Displacement, natural disasters, and climate change all contribute to the spread of cholera outbreaks. Despite increased vaccine production, shortages still exist. The Global Task Force on Cholera Control (GTFCC) aims to reduce cholera deaths worldwide by 90% by 2030.
Chikungunya
Chikungunya, a disease spread by Aedes mosquitoes, is another potential threat in 2025. It causes severe joint pain and fever, with symptoms sometimes lasting months or even years in extreme cases. In 2024, more than 480,000 cases and 200 deaths were reported worldwide. However, there is hope with a new vaccine recently approved in the U.S., and large studies are underway in East Africa to assess its impact. Preventing Chikungunya is crucial, as it can also increase the risk of developing arthritis.
COVID-19
COVID-19 remains a global concern in 2025, now mutated into the highly transmissible Omicron subvariant XEC. It continues to be one of the deadliest diseases, though vaccines remain effective in reducing severe outcomes. Health authorities recommend that everyone aged six months and older get the current COVID-19 vaccines. Ongoing research is being conducted on the virus’s evolution, and COVID-19 vaccines are now part of standard cost-effectiveness studies alongside routine immunizations.
Dengue Fever
Dengue fever cases have surged globally, with over 7.6 million reported and 3,000 deaths confirmed by April 2024. The Americas, in particular, have been hard hit. A new dengue vaccine, TAK-003, has been approved for use in children in high-risk areas. However, despite these advancements, the rising number of cases calls for enhanced monitoring, mosquito control, and public awareness to combat this widespread outbreak.
Measles
Measles is making an unexpected comeback, with global cases increasing by 20% between 2022 and 2023 due to a decline in vaccination rates. The drop in vaccination coverage during the pandemic resulted in the lowest rates since 2008. Europe, in particular, has seen a dramatic rise, with some countries reporting up to 45 times more cases. The United Kingdom even declared a “national incident.” Experts are stressing the need to boost vaccination efforts to prevent further outbreaks, but with many people now opposed to vaccines, this issue could persist.
Disease X
Disease X may sound like a concept from a science fiction movie, but it actually serves a crucial purpose. It is a placeholder for any unknown disease that could arise unexpectedly. The World Health Organization (WHO) introduced the concept of “Disease X” to highlight the importance of preparing for unforeseen health threats. COVID-19 vividly illustrated this need, showing how essential it is to study viral families as a whole. In late 2024, an epidemic in the Congo initially labeled as Disease X killed 79 people before it was diagnosed as a deadly strain of malaria.
Scabies
Scabies cases in the UK have surged dramatically, particularly in northern England, where the rate has tripled in recent years. This highly contagious skin condition spreads through close contact and leads to intense itching and redness. Topical creams and oral ivermectin are typically used to treat scabies. To effectively manage outbreaks, health authorities emphasize the importance of early detection and ensuring that close contacts, including asymptomatic individuals, are treated.
West Nile Fever
West Nile Fever is rapidly increasing across Europe, with 1,436 cases documented in 2024, nearly double the number from 2023. Countries like Greece, Italy, Spain, and Hungary have been hardest hit. Although most infections are asymptomatic, some cases can lead to severe complications such as encephalitis, which can be fatal. This highlights the need for better understanding and prevention of this potentially deadly mosquito-borne illness.
Whooping Cough
Whooping cough is also seeing a resurgence, with Australia recording the highest number of cases in 2024 than in any previous year. Infants under six months are especially vulnerable. Once again, declining vaccination rates are a major contributing factor, with many people failing to receive booster shots. Health experts are urging vaccinations, including the Tdap vaccine for pregnant women and caregivers, to protect infants and curb the spread of this dangerous disease.