There isn’t a single “new disease” dominating headlines the way COVID-19 did, but several emerging infections have caught the attention of global health authorities in 2024 and 2025. Some are newly discovered viruses, others are familiar pathogens behaving in unfamiliar ways. None currently poses a pandemic-level threat to the general public, but a few are worth knowing about depending on where you live or travel.
Oropouche Virus Is Spreading Beyond Its Usual Range
Oropouche virus has been the most geographically aggressive emerging infection of the past two years. Previously confined to the Amazon Basin, it spread to new countries throughout 2024 and into 2025. Cuba documented its first outbreak in 2024, with every province reporting cases. Barbados, Guyana, and Venezuela all recorded their first human cases during this same period. Travel-associated cases have also been identified in Europe, including in travelers returning from Dominica and Guatemala.
The virus spreads through the bites of infected midges, tiny flying insects smaller than mosquitoes. Symptoms resemble dengue fever: sudden high fever, headache, muscle and joint pain, and sometimes nausea. Most people recover within a week, though the illness can be quite unpleasant. There’s no vaccine or specific treatment. If you’re traveling to Central or South America, the Caribbean, or the Amazon region, insect bite prevention is the main line of defense.
Mpox Has a More Transmissible Variant
Mpox (formerly monkeypox) hasn’t disappeared. A newer variant called Clade Ib, first identified in the Democratic Republic of the Congo, has spread to nearby countries and caused travel-associated cases around the world. Unlike the Clade II strain that circulated widely in 2022, Clade Ib spreads primarily through close skin-to-skin contact, including sexual contact, and can also pass from mother to fetus or spread through household contact.
The mortality rate for Clade Ib is less than 0.5% in Central and Eastern Africa, with deaths concentrated among people with weakened immune systems. The population most affected in recent outbreaks has been adults, often sex workers and their close contacts, with subsequent spread through day-to-day household interactions. Vaccines are available and recommended for people at higher risk.
H5N1 Bird Flu in Humans
H5N1 avian influenza has infected 71 people in the United States as of the latest CDC count. That number sounds alarming, but a critical detail changes the picture: there is no known person-to-person spread. Every confirmed case has been linked to direct contact with infected animals, primarily poultry and dairy cattle. The virus remains primarily an occupational hazard for farmworkers rather than a community-level threat. Public health agencies continue watching H5N1 closely because influenza viruses mutate frequently, and any shift toward efficient human transmission would be a serious concern.
Chandipura Virus in India
Between June and August 2024, India reported 245 cases of acute encephalitis syndrome, with 82 deaths. Of those, 64 cases were confirmed as Chandipura virus infections. This is a virus spread by sandflies that causes rapid-onset brain inflammation, primarily in children. The case fatality rate for confirmed Chandipura infections is between 56% and 75%, making it one of the deadliest viruses currently causing outbreaks. There is no vaccine or specific treatment. The outbreak has remained localized in India, and the risk to international travelers is very low, but the WHO flagged it as a significant concern because diagnostic capacity for this virus is limited in many regions.
Borealpox: A Newly Named Virus in Alaska
Originally called Alaskapox, borealpox virus was first identified in 2015 near Fairbanks, Alaska. Only seven human cases have been documented total, including one fatal case in an older man living in a remote forested area on the Kenai Peninsula. The virus lives in red-backed voles and shrews, and domestic cats appear to act as intermediaries, carrying the virus from wild rodents to humans.
Symptoms include a painful red bump at the site of infection, smaller pox-like lesions elsewhere on the body, fever, swollen lymph nodes, muscle pain, and fatigue. Illness has lasted anywhere from four days to six months depending on the case. This virus is not spreading widely and poses essentially no risk outside rural Alaska, but it’s a reminder that new pathogens continue to emerge from animal populations.
Other Infections on the Radar
Enterovirus D68 has been surging across Europe. This respiratory virus can cause severe breathing problems and, rarely, neurological complications including limb weakness. Detection rates hit 20.6% of enterovirus-positive samples in 2024, the highest level recorded in a decade of surveillance across 18 European countries. The virus follows a roughly two-year cycle, though that pattern was disrupted by COVID-era public health measures.
A hybrid strain of E. coli caused an outbreak across the UK and mainland Europe, combining two types of disease-causing mechanisms that don’t normally appear together in the same bacterium. The strain produced 18 confirmed cases plus several additional linked infections in Scotland and Belgium. Unusually, no children were affected, which researchers attribute to the strain’s outer coating triggering cross-protection from a common childhood meningitis vaccine.
What “Disease X” Actually Means
If you’ve seen the term “Disease X” in the news, it’s not a real disease. It’s a placeholder on the WHO’s priority research list, representing the idea that the next pandemic could come from a pathogen we haven’t identified yet. The concept exists to push governments, pharmaceutical companies, and public health agencies to build flexible preparedness systems (vaccine platforms that can be adapted quickly, home testing infrastructure, genomic surveillance networks) rather than only preparing for known threats.
The WHO’s current priority disease list includes COVID-19, Ebola, Marburg, Lassa fever, MERS, SARS, Nipah virus, Rift Valley fever, Zika, Crimean-Congo hemorrhagic fever, and Disease X. These are pathogens considered most likely to cause a future public health emergency and most in need of accelerated research.
Practical Steps for Staying Protected
The CDC issues tiered travel health notices ranging from Level 1 (practice usual precautions) to Level 4 (avoid all travel). Checking these notices before international trips is the simplest way to stay informed about active outbreaks at your destination.
For most of the emerging infections on this list, prevention comes down to a few basics. Prevent insect bites when traveling to tropical or subtropical regions, since midges, mosquitoes, and sandflies transmit Oropouche, dengue, chikungunya, and Chandipura. Make sure routine vaccinations are current before international travel, particularly measles, polio, and diphtheria. Avoid direct contact with unfamiliar animals, especially in rural areas where zoonotic viruses like borealpox and H5N1 circulate. And if you’re at higher risk for mpox, talk to a healthcare provider about vaccination.