Disease Outbreaks
Disease Outbreaks
Disease outbreaks remain a persistent global public-health challenge, ranging from localized clusters of foodborne illness to large epidemics involving highly transmissible or deadly pathogens. Recent outbreaks demonstrate the wide variety of circumstances that allow infectious diseases to emerge, return, or spread into new populations. These include zoonotic spillover from animals, declining vaccination coverage, international travel, changing mosquito distributions, contaminated food and water, conflict, displacement, and weaknesses in health-care and surveillance systems.
The outbreaks documented here include Ebola, Marburg virus disease, Lassa fever, mpox, Nipah virus, MERS, measles, dengue, yellow fever, Oropouche fever, chikungunya, avian influenza, cholera, polio, meningitis, diphtheria, hepatitis, pertussis, Salmonella, Listeria, E. coli, norovirus, and numerous other infectious diseases. Together they illustrate both the diversity of outbreak threats and the increasingly interconnected systems through which diseases move among people, animals, food supplies, and environments.
Emerging Viral and Zoonotic Outbreaks
Some of the most serious outbreaks involve viruses capable of crossing between animals and humans or producing severe disease after entering human populations. Ebola and Marburg outbreaks in Africa repeatedly demonstrate the importance of rapid diagnosis, contact tracing, isolation, treatment, vaccination where available, and community cooperation. Delayed detection, weak health systems, population movement, and conflict can make containment substantially more difficult.
Mpox has likewise demonstrated how a disease once concentrated geographically can develop sustained transmission across multiple countries. Outbreak investigations have documented transmission in Africa, Europe, the United States, and highly mobile populations such as travelers and cruise-ship passengers. The emergence of different viral clades and reports of antiviral resistance further illustrate how continuing transmission can create new challenges for treatment and surveillance.
Nipah virus remains a recurring zoonotic threat in South Asia, where infections linked to animal-to-human spillover can trigger intensive contact tracing because of the disease's severity and potential for limited person-to-person transmission. Middle East respiratory syndrome coronavirus continues to produce sporadic infections and health-care-associated clusters, particularly in Saudi Arabia.
Avian influenza represents another major One Health concern. H5 viruses have circulated among wild birds, poultry, mammals, and occasionally humans. Recent outbreaks demonstrate the capacity of highly pathogenic avian influenza to move between species, produce mass wildlife mortality, threaten endangered animals, and generate unusual human infections. Surveillance of wildlife, livestock, poultry, and people therefore increasingly overlaps.
Vaccine-Preventable and Vector-Borne Diseases
The resurgence of measles illustrates how rapidly a highly contagious vaccine-preventable disease can return when immunity gaps develop. Outbreaks in the United States, Europe, Africa, and the wider Americas have repeatedly been associated with communities where vaccination coverage is insufficient to interrupt transmission. International travel can introduce infections into susceptible populations, while conflict and displacement can delay vaccination campaigns and increase the difficulty of outbreak control.
Other vaccine-preventable diseases remain important outbreak threats. Diphtheria has re-emerged in areas with low childhood immunization, while meningococcal disease and pertussis have produced substantial regional outbreaks. Poliovirus outbreaks demonstrate the continuing importance of maintaining high vaccination coverage, particularly in populations affected by displacement, overcrowding, poor sanitation, or limited access to routine health services.
Mosquito- and insect-borne diseases are also expanding or reappearing in many regions. Dengue has produced record or near-record levels of disease in several parts of the world, while yellow fever continues circulating in Africa and the Americas. Oropouche virus has expanded beyond areas where it was historically recognized, with investigations examining severe disease and possible pregnancy-related complications.
Chikungunya and West Nile virus activity in Europe demonstrate how the geography of vector-borne diseases can change. Expanding mosquito ranges, favorable environmental conditions, international travel, and movement of infected people can allow local transmission to occur in regions where such outbreaks were previously uncommon.
Cholera, Foodborne Disease, and Environmental Outbreaks
Cholera outbreaks repeatedly demonstrate the close relationship between infectious disease and access to safe water, sanitation, housing, and health care. Major outbreaks have occurred in countries affected by conflict, displacement, flooding, damaged infrastructure, and poverty. In places such as Sudan, Angola, Zambia, and the Democratic Republic of the Congo, humanitarian emergencies have compounded the difficulty of controlling waterborne disease.
Foodborne outbreaks form another major category of disease events. Investigations have linked Salmonella, Listeria, E. coli, hepatitis A, Cyclospora, Cronobacter, botulism, and other illnesses to a wide variety of foods and consumer products. Foods implicated in outbreaks have included eggs, cucumbers, sprouts, leafy greens, cheeses, raw milk products, frozen fruit, onions, cantaloupes, flour, peanut butter, infant formula, ice cream, mushrooms, seafood, prepared meals, and other commercially distributed products.
These investigations demonstrate the importance of epidemiological interviews, genomic surveillance, product traceback, environmental sampling, recalls, and coordination among public-health and food-safety agencies. Because modern food distribution networks can move contaminated products across large geographic areas, a single contamination event may produce illnesses in multiple jurisdictions before investigators identify the source.
Environmental exposures can also generate outbreaks. Examples include fungal infections associated with caves, Legionnaires' disease linked to contaminated water systems, hepatitis and enteric disease detected through wastewater surveillance, and disease transmission associated with animal contact. Such events demonstrate that outbreak surveillance must extend beyond hospitals and clinics to food systems, water infrastructure, animals, and the broader environment.
Conflict, Displacement, Travel, and Outbreak Vulnerability
Many outbreaks are intensified by conditions that weaken the ability of communities and governments to prevent or control disease. Armed conflict can damage hospitals, interrupt vaccination campaigns, displace populations, contaminate water supplies, and make epidemiological surveillance difficult or impossible. Outbreak responses in Sudan and the Democratic Republic of the Congo illustrate how disease emergencies can worsen when public-health systems are simultaneously confronting violence and humanitarian crises.
Population movement is another recurring factor. Refugee settlements, transportation corridors, international travel, pilgrimages, cruise ships, and cross-border communities can connect outbreaks that would otherwise remain geographically limited. Surveillance and communication between jurisdictions are therefore essential components of modern outbreak response.
Emergency shelters can themselves become outbreak environments when large numbers of displaced people share crowded facilities. Investigations following natural disasters and other emergencies have documented simultaneous outbreaks of respiratory and gastrointestinal infections, demonstrating how rapidly several pathogens can circulate under crowded conditions.
Surveillance, Vaccination, and One Health
A central lesson across these outbreaks is the importance of early detection. Traditional case reporting remains essential, but newer approaches such as genomic sequencing, wastewater surveillance, digital surveillance, and international disease-monitoring networks can reveal transmission that might otherwise remain undetected.
Vaccination remains one of the most important tools for preventing or containing many outbreaks. Measles, yellow fever, polio, mpox, Ebola, meningococcal disease, and other outbreaks demonstrate how vaccination can either prevent transmission or become an important emergency intervention after an outbreak begins. Conversely, declining vaccination coverage or delayed access to vaccines can leave populations susceptible to renewed epidemics.
The growing importance of zoonotic infections also supports a One Health approach that considers human, animal, and environmental health together. Avian influenza, anthrax, leptospirosis, Salmonella associated with animal contact, and other outbreaks cannot be understood solely as human medical problems. Wildlife, livestock, agriculture, ecosystems, food production, and environmental conditions can all influence when and where infectious diseases emerge.
Conclusion
Disease outbreaks are not caused by pathogens alone. Their scale and consequences are shaped by vaccination coverage, health infrastructure, environmental conditions, food and water safety, animal health, population movement, social trust, political stability, and the ability of public-health systems to detect infections quickly.
The wide range of outbreaks documented in recent years demonstrates that infectious-disease preparedness requires more than responding to individual emergencies. Effective prevention depends on sustained disease surveillance, vaccination, laboratory capacity, safe food and water systems, international cooperation, rapid outbreak investigation, resilient health services, and closer integration of human, animal, and environmental health.
Taken together, these outbreaks show that emerging and re-emerging diseases are a continuing feature of global public health. The challenge is not simply predicting which pathogen will appear next, but building systems capable of recognizing unusual disease quickly and responding before localized transmission becomes a much larger epidemic.
Ebola, Marburg, Lassa Fever, and Hemorrhagic Disease Outbreaks
The international response to Congo's Ebola crisis includes a major vaccine deployment as health authorities attempt to interrupt transmission and protect vulnerable populations.
Ebola cases in Congo exceed 5,000, government data shows | Reuters | Reuters | August 19, 2026
The Democratic Republic of the Congo's rapidly expanding Ebola outbreak surpassed 5,000 reported cases, illustrating how conflict, weak health infrastructure, delayed detection, and community mistrust can complicate outbreak control.
WHO officials argue that the expanding outbreak remains containable if surveillance, contact tracing, treatment capacity, community cooperation, and financing can be strengthened.
WHO documents the intensification and geographic expansion of the Bundibugyo Ebola outbreak across multiple provinces of the Democratic Republic of the Congo.
The report tracks sustained Ebola transmission, rising deaths, affected health zones, international medical evacuations, and regional response efforts.
WHO describes rapidly increasing case numbers and cross-border implications as the Bundibugyo Ebola outbreak develops.
Surveillance data show sustained Ebola transmission in eastern Congo while Uganda monitors infections epidemiologically connected to the outbreak.
WHO reports increasing cases and geographic spread while laboratory capacity and contact tracing are expanded.
The outbreak demonstrates the importance of cross-border surveillance when an epidemic expands through highly mobile populations.
WHO launches $518 million plan to curb Africa Ebola outbreak | Reuters | Reuters | June 5, 2026
WHO and partners developed a large regional response plan aimed at controlling Ebola in affected countries while strengthening preparedness in neighboring states.
WHO describes the early acceleration of an Ebola outbreak involving confirmed infections in both Congo and Uganda.
Marburg virus disease - Ethiopia | World Health Organization | WHO | November 21, 2025
Ethiopia's first recognized Marburg outbreak illustrates the challenges posed when a rare hemorrhagic disease appears in a country already managing several other epidemics.
WHO reviews Tanzania's Marburg outbreak and its conclusion following two incubation periods without another confirmed infection.
Marburg virus disease - Equatorial Guinea | World Health Organization | WHO | June 9, 2023
Equatorial Guinea declared its first known Marburg outbreak over after weeks without additional confirmed cases.
WHO compares simultaneous but separate Marburg outbreaks in two African countries and the public-health responses used to contain them.
Lassa fever - Nigeria | World Health Organization | WHO | May 1, 2023
Nigeria's large seasonal Lassa fever outbreak demonstrates how endemic zoonotic diseases can repeatedly generate substantial epidemics.
Marburg virus disease - Equatorial Guinea | World Health Organization | WHO | April 15, 2023
The widening geographic distribution of Marburg infections raised concerns that transmission chains were not being detected quickly enough.
Marburg virus disease - Equatorial Guinea | World Health Organization | WHO | March 22, 2023
Additional confirmed cases across separated provinces suggested wider transmission during Equatorial Guinea's first Marburg outbreak.
Marburg virus disease - Equatorial Guinea | World Health Organization | WHO | February 25, 2023
WHO describes the initial investigation that established Equatorial Guinea's first documented Marburg virus disease outbreak.
Marburg virus disease - Guinea | World Health Organization | WHO | September 17, 2021
Guinea's first Marburg outbreak involved a single confirmed patient and shows the importance of rapid surveillance and contact tracing after detection of a rare pathogen.
Mpox, Nipah, MERS, and Emerging Viral Outbreaks
A new West African mpox outbreak highlights the disease's impact on children and the surveillance limitations faced by fragile health systems.
Nipah virus disease - India | World Health Organization | WHO | June 25, 2026
A confirmed Nipah infection in Kerala prompted intensive identification and monitoring of contacts because of the virus's potential for severe disease and person-to-person transmission.
MERS continues to produce zoonotic spillovers and occasional health-care-associated clusters more than a decade after the virus was identified.
Nipah virus infection - India | World Health Organization | WHO | August 6, 2025
WHO reviews another cluster of Nipah infections in Kerala, where recurring spillover has made surveillance and outbreak preparedness particularly important.
Kenya's outbreak became concentrated along an important transportation corridor, showing how mobility networks can influence infectious-disease spread.
Investigation of mpox aboard cruise ships illustrates the surveillance challenges posed by highly mobile populations.
COVID-19 - Global Situation | World Health Organization | WHO | May 28, 2025
WHO reported renewed global SARS-CoV-2 activity and shifting variant patterns, demonstrating that outbreak surveillance continues after the pandemic emergency phase.
A hospital-associated MERS cluster involving health workers demonstrates the continued potential for coronavirus transmission in medical settings.
WHO documents sporadic MERS infections and a limited episode of nosocomial transmission in Saudi Arabia.
Investigation of an unexplained cluster of rapidly fatal illnesses demonstrates how outbreak response begins before the responsible pathogen or environmental cause is known.
Authorization of an mpox vaccine for young children expanded the tools available for protecting a population heavily affected during the African outbreak.
Nigeria begins delayed mpox vaccination programme | Reuters | Reuters | November 18, 2024
Nigeria began targeted vaccination of health workers and immunocompromised people as African countries attempted to contain expanding mpox transmission.
Detection of drug-resistant mpox viruses illustrates how pathogen evolution can complicate treatment during continuing transmission.
Mpox - Sweden | World Health Organization | WHO | August 30, 2024
Sweden reported the first recognized clade Ib mpox infection outside Africa, illustrating the potential for international spread through travel.
Mpox - African Region | World Health Organization | WHO | August 22, 2024
WHO describes the international expansion of clade Ib mpox from the Democratic Republic of the Congo into neighboring African countries.
Mpox - South Africa | World Health Organization | WHO | July 9, 2024
Severe mpox cases among people with advanced HIV highlighted how underlying health conditions can shape mortality during an outbreak.
Mpox - Democratic Republic of the Congo | World Health Organization | WHO | June 14, 2024
WHO documents sustained community transmission, geographic expansion, and emergence of a new clade I lineage during Congo's mpox epidemic.
Emergency-department surveillance evaluated whether broader clinical screening could identify previously unsuspected mpox transmission.
Mpox transmission persisted at low levels in the United States long after the dramatic decline from the 2022 epidemic peak.
Mpox Outbreak - Los Angeles County, California, May-August 2023 | CDC | MMWR | January 18, 2024
Investigation of a localized resurgence provides insight into the transmission networks capable of sustaining mpox after the initial global epidemic.
Measles, Vaccination, and Vaccine-Preventable Outbreaks
Declining childhood vaccination and growing exemption rates increase the number of communities capable of sustaining outbreaks of measles and other preventable diseases.
Measles Cases and Outbreaks | Centers for Disease Control and Prevention | CDC | July 2, 2026
CDC surveillance documents the resurgence of measles and the large proportion of infections associated with recognized outbreaks.
A small outbreak demonstrates how measles exposure in emergency departments can create substantial contact-tracing burdens.
Researchers show that wastewater sequencing can detect even very limited measles circulation, potentially improving early outbreak warning.
Although European measles cases declined from their 2024 peak, continuing community transmission demonstrated that substantial immunity gaps remained.
County-level vaccination estimates demonstrate how apparently strong national coverage can conceal communities vulnerable to measles outbreaks.
Conflict and displacement delayed vaccination during a deadly measles epidemic in eastern Congo, demonstrating how insecurity can magnify preventable disease.
Continued geographic spread of measles underscored the importance of closing vaccination gaps before imported infections establish transmission chains.
Measles cases rise in the Americas in 2025 | Pan American Health Organization | PAHO | July 3, 2025
PAHO reported a dramatic regional increase in measles infections and deaths, particularly in Canada, Mexico, and the United States.
The Texas epidemic illustrates both how outbreaks can decline locally and how infectious travelers can seed transmission elsewhere.
Measles - Morocco | World Health Organization | WHO | May 13, 2025
Morocco's widespread epidemic shows how measles can regain sustained circulation when national and local vaccination gaps develop.
Measles - Region of the Americas | World Health Organization | WHO | April 28, 2025
Measles cases across the Americas increased sharply as imported infections encountered pockets of inadequate vaccination coverage.
CDC epidemiologists examine the epidemiology of the U.S. measles resurgence, including vaccination status, imported infections, hospitalization, and outbreak-associated cases.
Measles - United States of America | World Health Organization | WHO | March 27, 2025
WHO reported an unusual U.S. measles outbreak dominated by infections among unvaccinated people and communities with immunity gaps.
European surveillance showed tens of thousands of infections following declining vaccination coverage in several countries.
Detection of severe neonatal infections in several European countries expanded concern from a French cluster into a broader regional surveillance event.
Enterovirus Infection - France | World Health Organization | WHO | May 31, 2023
An unusual cluster of severe neonatal Echovirus-11 infections demonstrates how changes in pathogen circulation can produce unexpectedly severe outbreaks.
The Disneyland-associated measles outbreak became a prominent example of how an imported infection can spread through clusters of susceptible people.
Measles - United States, 1995 | Centers for Disease Control and Prevention | CDC MMWR | 1996
National surveillance of measles in 1995 documents numerous outbreaks and shows the continuing importance of imported infections even as elimination approached.
Measles Outbreak - Chicago, 1989 | Centers for Disease Control and Prevention | CDC MMWR | 1989
Chicago's large measles epidemic illustrates the severe consequences that can occur when vaccination coverage remains inadequate in vulnerable communities.
Dengue, Yellow Fever, Oropouche, and Vector-Borne Outbreaks
An unusual wildlife vaccination campaign shows how conservation agencies are adapting disease-control tools to protect vulnerable wild bird populations.
Australia confirms first H5N1 bird flu case in local mammal | Reuters | Reuters | August 23, 2026
Detection of H5N1 in an Australian fur seal demonstrates the continuing ability of avian influenza to cross species barriers during wildlife outbreaks.
Yellow fever - Global | World Health Organization | WHO | June 24, 2026
WHO documents continuing yellow fever transmission in Africa and the Americas and emphasizes persistent risk among poorly vaccinated populations.
Record dengue activity among U.S. travelers demonstrates how international epidemics increase the risk of imported and locally transmitted disease.
Oropouche fever continued spreading across the Americas, including areas with little previous history of transmission.
PAHO warns that continuing infections and geographic expansion make vaccination and surveillance critical for preventing larger epidemics.
Yellow fever - Region of the Americas | World Health Organization | WHO | May 16, 2025
A major rise in yellow fever infections and deaths illustrates the consequences of sylvatic transmission reaching susceptible populations.
Yellow fever cases more than doubled previous annual totals during the opening months of 2025, including infections outside traditionally affected areas.
Puerto Rico's first declared dengue outbreak since 2013 produced thousands of cases, substantial hospitalization, severe disease, and deaths.
Health authorities identified an early-2025 increase in yellow fever and a change in the disease's geographic distribution.
The Americas simultaneously faced record dengue activity, expanding Oropouche transmission, and continuing H5N1 infections, illustrating the challenge of overlapping outbreaks.
PAHO issues update on Oropouche fever | PAHO | Pan American Health Organization | October 16, 2024
More than 10,000 confirmed infections and detection in additional countries prompted calls for stronger diagnosis, surveillance, and vector control.
Oropouche spread into areas without previous recognized transmission while investigators studied deaths and possible vertical transmission.
Regional health officials responded to rapidly increasing infections, geographic expansion, and reports of serious outcomes.
Q&A - Oropouche fever | PAHO | Pan American Health Organization | July 24, 2024
PAHO explains the emerging outbreak, transmission by biting midges and mosquitoes, clinical symptoms, and regional surveillance efforts.
Investigation of possible vertical transmission raised concern that an expanding arbovirus outbreak could present previously underrecognized pregnancy risks.
Governments strengthened surveillance as Oropouche expanded beyond its historically recognized geographic range.
Dengue - Global situation | World Health Organization | WHO | May 30, 2024
More than seven million dengue cases were reported within the first four months of 2024 as the mosquito-borne disease surged globally.
Yellow fever - African Region | World Health Organization | WHO | March 20, 2024
Thirteen African countries reported probable or confirmed yellow fever infections amid concerns about vaccination gaps and urban mosquito populations.
Yellow Fever - Kenya | World Health Organization | WHO | March 25, 2022
Kenya declared a yellow fever outbreak following suspected cases and deaths in Isiolo County, its first reported outbreak in more than a decade.
Avian Influenza, Cholera, Polio, Foodborne Disease, and One Health
Scientists fear H5N1 could cause major mortality among endangered Australian sea lions after the virus established itself in regional wildlife.
The first confirmed mammalian infection on Australia's mainland marks a significant expansion of the country's H5 outbreak.
Mass seabird mortality illustrates the ecological effects that highly pathogenic avian influenza can produce after entering previously unaffected wildlife populations.
The first recognized human H5N5 infection globally reinforced concerns about the continuing diversification of avian influenza viruses.
Enhanced influenza surveillance detected an H5N1 infection in a San Francisco child despite investigators finding no clear source of exposure.
WHO describes worsening cholera outbreaks driven by conflict, displacement, poverty, flooding, inadequate sanitation, and limited access to medical care.
Avian Influenza A(H5N1) - Cambodia | World Health Organization | WHO | July 5, 2025
Cambodia reported an unusual concentration of human H5N1 infections linked primarily to exposure to infected poultry.
One of the largest recent U.S. outbreaks associated with raw milk disproportionately affected children and illustrates the protection provided by pasteurization.
Ivory Coast announces cholera outbreak after 7 deaths | Associated Press | AP | June 5, 2025
A localized outbreak near Abidjan led authorities to emphasize safe drinking water, sanitation, and rapid laboratory confirmation.
Purchase records and genomic surveillance helped investigators rapidly connect a multistate Salmonella outbreak with contaminated charcuterie products.
Avian Influenza A(H5N1) - Mexico | World Health Organization | WHO | April 17, 2025
Mexico's first laboratory-confirmed human H5N1 infection prompted investigation of possible exposure to infected birds.
Cholera - Angola | World Health Organization | WHO | March 28, 2025
Angola's rapidly expanding cholera epidemic affected most provinces and produced a substantial death toll despite vaccination and public-health interventions.
Damage to water infrastructure during Sudan's conflict contributed to an explosive cholera outbreak that rapidly overwhelmed treatment capacity.
Conflict, climate-related disasters, unsafe water, failing sanitation infrastructure, displacement, and vaccine shortages are driving a global cholera resurgence.
Analysis of hundreds of outbreaks shows the importance of the One Health connection between human disease, backyard poultry, livestock, reptiles, pets, and other animal exposures.
H5N1 infections among captive birds and mammals show how wildlife outbreaks can threaten endangered species as well as agricultural animals.
Bird flu found in western China as US combats cattle outbreak | Reuters | Reuters | May 18, 2024
Detection of avian influenza among wild birds in China occurred while public-health authorities were closely watching the unprecedented U.S. dairy-cattle outbreak.
Zambia's severe epidemic illustrates how heavy rainfall, unsafe water, inadequate sanitation, and vaccine shortages can combine to create a major cholera emergency.
Detection of new paralytic polio cases prompted supplementary vaccination campaigns aimed at stopping community circulation.
Poliovirus detected in a large refugee camp illustrates how low vaccination coverage, overcrowding, poor sanitation, and population movement can combine to facilitate outbreaks.
Emerging Viral, Vector-Borne, and Zoonotic Disease Outbreaks
France reported locally acquired chikungunya clusters during the 2026 mosquito season, demonstrating the continuing expansion of conditions suitable for transmission in mainland Europe.
Global surveillance recorded hundreds of thousands of chikungunya infections across multiple continents, illustrating the growing international burden of this mosquito-borne disease.
Numerous infections among travelers returning from Seychelles provided evidence of substantial chikungunya transmission across Indian Ocean island populations.
Congo declared its Ebola outbreak over after two incubation periods without another infection, following dozens of confirmed and probable cases.
Nipah virus infection - Bangladesh | World Health Organization | WHO | September 18, 2025
Several fatal Nipah infections occurred independently across Bangladesh, reinforcing the persistent risk of bat-to-human spillover.
Confirmation of Ebola in Kasai Province triggered intensive surveillance, contact tracing, laboratory testing, treatment, and vaccination activities.
Record chikungunya and West Nile activity in Europe illustrates how warming temperatures, expanding mosquito ranges, and international travel are altering outbreak geography.
European health authorities expanded mosquito-borne disease surveillance as locally acquired dengue, chikungunya, and West Nile infections became increasingly important public-health threats.
Tanzania reported confirmed and probable Marburg infections while hundreds of exposed contacts completed monitoring.
Fighting in eastern Congo disrupted surveillance, treatment, vaccination, and reporting during an already difficult mpox epidemic.
Reports of unexplained hemorrhagic illness in Tanzania's Kagera region triggered rapid testing, surveillance, and an international outbreak response.
Marburg virus disease - Rwanda | World Health Organization | WHO | December 20, 2024
Rwanda officially declared its first Marburg outbreak over after reporting 66 confirmed cases and 15 deaths.
Oropouche transmission expanded across the Americas during 2024, with more countries reporting infections as well as travel-associated cases outside the region.
Marburg virus disease - Rwanda | World Health Organization | WHO | November 13, 2024
With no new infections detected, Rwanda began the 42-day countdown required before an outbreak could officially be declared over.
Marburg virus disease - Rwanda | World Health Organization | WHO | November 1, 2024
Rwanda's outbreak reached 66 confirmed infections as surveillance, treatment, contact tracing, and experimental countermeasure efforts continued.
Marburg virus disease - Rwanda | World Health Organization | WHO | October 11, 2024
Rapid growth of Rwanda's Marburg outbreak prompted WHO to classify the emergency at its highest internal response level.
Marburg virus disease - Rwanda | World Health Organization | WHO | September 30, 2024
Rwanda confirmed its first Marburg outbreak, with many early infections occurring among health-care workers.
India experienced its largest Chandipura virus-associated encephalitis outbreak in roughly two decades, with children particularly vulnerable to severe and fatal disease.
Oropouche virus disease - Region of the Americas | World Health Organization | WHO | August 23, 2024
The rapidly expanding Oropouche outbreak included thousands of infections, deaths, and investigations into possible pregnancy-related complications.
A cluster of epidemiologically linked MERS cases in Riyadh demonstrated the continuing potential for health-care-associated coronavirus transmission.
Meningitis, Diphtheria, Hepatitis, and Other Bacterial or Preventable Outbreaks
Crowded emergency shelter conditions following the Eaton wildfire enabled simultaneous norovirus, COVID-19, influenza, and respiratory-disease outbreaks.
A contaminated hot tub at a New York vacation rental was linked to multiple Legionnaires' disease infections.
More than 200,000 pertussis cases were reported across the EU/EEA during 2024, an enormous increase compared with preceding years.
An extended family developed histoplasmosis after cave exposure in Costa Rica, illustrating the outbreak risks associated with environments contaminated by bat droppings.
Wastewater surveillance detected evidence of hepatitis A transmission that conventional case reporting alone could have missed.
Virginia recorded an unusually prolonged meningococcal outbreak involving 36 cases and seven deaths.
Meningococcal infections among pilgrims and household contacts demonstrated how international mass gatherings can facilitate transmission across national borders.
Europe experienced a dramatic resurgence of whooping cough following several years of unusually low circulation during the COVID-19 period.
Hepatitis E - Chad | World Health Organization | WHO | May 8, 2024
More than 2,000 suspected hepatitis E infections occurred mainly among Sudanese refugees living in camps with inadequate water and sanitation.
Anthrax - Zambia | World Health Organization | WHO | December 8, 2023
Zambia experienced an unusually widespread anthrax outbreak affecting people, livestock, and wildlife across nine of the country's ten provinces.
Diphtheria - Guinea | World Health Organization | WHO | October 18, 2023
Hundreds of cases and dozens of deaths occurred during Guinea's diphtheria outbreak, with extremely low childhood vaccination coverage contributing to transmission.
Botulism - France | World Health Organization | WHO | September 20, 2023
Homemade preserved sardines served at a Bordeaux restaurant caused an international botulism outbreak involving visitors from several countries.
Diphtheria - Nigeria | World Health Organization | WHO | September 13, 2023
A second wave dramatically increased Nigeria's diphtheria burden, with unvaccinated children accounting for a large proportion of infections.
Patients developed serious fungal meningitis after undergoing procedures at clinics in Matamoros, Mexico, creating a binational U.S.-Mexico investigation.
Diphtheria - Nigeria | World Health Organization | WHO | April 27, 2023
Nigeria reported hundreds of confirmed diphtheria infections across numerous states during a large resurgence of the vaccine-preventable disease.
Meningitis - Nigeria | World Health Organization | WHO | April 27, 2023
Nigeria reported more than 1,600 suspected meningitis cases during an outbreak concentrated heavily in Jigawa State.
Pneumococcal meningitis - Togo | World Health Organization | WHO | April 11, 2023
Togo experienced its first recognized pneumococcal meningitis outbreak, affecting many children and adolescents in the African meningitis belt.
Iatrogenic Botulism - European Region | World Health Organization | WHO | March 24, 2023
Dozens of patients developed botulism after receiving botulinum toxin procedures at medical facilities in Türkiye.
Meningitis - Niger | World Health Organization | WHO | February 8, 2023
A serogroup C meningococcal epidemic in Niger's Zinder region prompted mass reactive vaccination and strengthened cross-border surveillance.
Leptospirosis - United Republic of Tanzania | World Health Organization | WHO | August 12, 2022
A cluster of leptospirosis among agricultural workers highlighted the relationship between occupational exposure, animals, contaminated environments, and disease outbreaks.
Foodborne and Consumer-Product Outbreaks - 2025-2026
Multiple E. coli strains and Salmonella were linked to alfalfa sprouts during a multistate outbreak investigation.
Fresh jalapeños imported from Mexico were investigated as the source of a multistate Salmonella outbreak.
Outbreak Investigation of Salmonella: Eggs | U.S. Food and Drug Administration | FDA | July 2026
Federal and state authorities investigated shell eggs associated with a multistate Salmonella outbreak.
Traceback work linked a cluster of cyclosporiasis infections to iceberg lettuce distributed through the food supply.
Frozen blueberries became the focus of a multistate Shiga toxin-producing E. coli investigation.
An infant botulism investigation examined powdered formula as a possible exposure source.
Soft cheese products were associated with a Listeria outbreak that required recalls and epidemiological investigation.
Moringa leaf powder was investigated after illnesses were linked epidemiologically to Salmonella contamination.
Raw-milk cheddar cheese was linked to infections caused by E. coli O157:H7.
Detection of extensively drug-resistant Salmonella in a food-associated outbreak added antimicrobial resistance to the challenges facing investigators.
A separate Salmonella investigation linked illnesses to contaminated moringa leaf powder products.
Federal investigators examined reports of infant botulism potentially associated with commercially distributed infant formula.
Salmonella infections prompted recalls and traceback investigations involving moringa leaf powder.
Outbreak Investigation of Salmonella: Eggs | U.S. Food and Drug Administration | FDA | August 2025
Shell eggs were identified during an outbreak investigation involving Salmonella infections across multiple jurisdictions.
Frozen prepared foods sold under the Deep brand were linked to Salmonella illnesses.
Prepared pasta meals were investigated and recalled during a multistate outbreak of invasive listeriosis.
Pistachio cream was identified as a potential vehicle for Salmonella transmission.
Outbreak Investigation of Salmonella: Eggs | U.S. Food and Drug Administration | FDA | June 2025
A separate 2025 Salmonella outbreak was linked to eggs and led to recalls and traceback investigations.
Outbreak Investigation of Salmonella: Cucumbers | U.S. Food and Drug Administration | FDA | May 2025
Fresh cucumbers were identified as a source during another multistate Salmonella investigation.
Ready-to-eat foods contaminated with Listeria prompted a complex outbreak investigation and product recalls.
Foodborne Disease Outbreaks - 2022-2025
Frozen nutritional shakes served primarily to institutional populations were linked to a serious Listeria outbreak.
Imported mini pastries were investigated following detection of Salmonella infections.
Cucumbers grown in Mexico were linked through epidemiological and traceback evidence to more than 100 Salmonella illnesses.
Organic carrots were recalled after epidemiological evidence linked them with a multistate outbreak of Shiga toxin-producing E. coli.
Slivered onions supplied to restaurants were identified as the likely source of a large E. coli O157:H7 outbreak.
Egg-associated Salmonella infections led regulators to conduct traceback, environmental sampling, and recall activities.
Hundreds of illnesses across the United States were eventually connected with cucumbers contaminated by multiple Salmonella strains.
Bulk organic walnuts sold in natural-food stores were associated with an outbreak of E. coli O157:H7.
Organic basil became the focus of a Salmonella investigation after multiple illnesses were reported.
Raw cheddar cheese was linked with infections caused by Shiga toxin-producing E. coli.
A long-running outbreak was ultimately traced to queso fresco and cotija cheeses contaminated with Listeria.
Whole stone fruit was connected with a multiyear Listeria outbreak causing hospitalizations and death.
Contaminated cantaloupes caused hundreds of illnesses, more than 150 hospitalizations, and multiple deaths.
Fresh onions were investigated and recalled after being linked to Salmonella infections.
Ice cream contamination prompted a Listeria outbreak investigation and recall.
Consumption of raw cookie dough was linked to Salmonella infections, underscoring the risks associated with uncooked flour-containing foods.
Investigation of Illnesses: Morel Mushrooms | U.S. Food and Drug Administration | FDA | May 2023
A restaurant-associated outbreak involving morel mushrooms demonstrated that outbreaks can involve natural toxins as well as infectious pathogens.
Outbreak Investigation of Salmonella: Flour | U.S. Food and Drug Administration | FDA | April 2023
Raw flour was identified as the vehicle in a Salmonella outbreak, reinforcing advice against tasting uncooked dough and batter.
Imported frozen strawberries were linked with hepatitis A infections and prompted recalls and vaccination recommendations for some exposed consumers.
Alfalfa sprouts were connected with a multistate Salmonella outbreak, highlighting the persistent microbial risks associated with raw sprouts.
Additional Foodborne, Environmental, Humanitarian, and Outbreak Research
NoroSTAT Data Table | Centers for Disease Control and Prevention | CDC | June 18, 2026
National surveillance tracks changes in reported norovirus outbreaks and provides an important early-warning system for unusually intense gastrointestinal-disease seasons.
CaliciNet Data | Centers for Disease Control and Prevention | CDC | 2026
Genetic surveillance of norovirus outbreaks helps identify emerging variants and connect apparently separate outbreaks caused by related virus strains.
Two simultaneous but genetically distinct norovirus outbreaks sickened consumers who ate raw oysters harvested from separate regions of Mexico.
Mpox still a health emergency, says WHO | Reuters | Reuters | February 27, 2025
WHO maintained its highest international alert as clade Ib mpox continued spreading geographically across Central and East Africa.
Threat of disease in DRC multiplied by conflict, WHO says | Reuters | Reuters | February 7, 2025
Fighting around Goma sharply increased risks from cholera, malaria, tuberculosis, mpox, and other diseases while simultaneously weakening outbreak response.
Are we ready for another pandemic? | The Guardian | The Guardian | January 2, 2025
Repeated outbreaks of mpox, Marburg, cholera, dengue, measles, diphtheria, and avian influenza demonstrate the continuing strain placed on global outbreak-response systems.
Cholera spreads as Sudan grapples with rains and displacement | Reuters | Reuters | August 23, 2024
War, mass displacement, damaged health infrastructure, flooding, and poor sanitation created conditions for another serious cholera epidemic in Sudan.
A broad scientific review examines how emerging and resurgent viruses including dengue, measles, influenza, and other pathogens threaten children and global health systems.
Simultaneous cholera and dengue epidemics emerged as war damaged hospitals, displaced millions, and reduced access to safe water.
Imported enoki mushrooms were linked with Listeria infections, continuing a history of international outbreaks involving this product.
Seafood products were implicated during a Salmonella outbreak investigation involving federal and state public-health agencies.
Frozen falafel was linked with illnesses caused by Shiga toxin-producing E. coli O121:H19.
Soft-ripened cheeses were recalled following detection of a multistate Listeria outbreak.
An ice cream-associated Listeria outbreak led to hospitalization of affected consumers and extensive environmental investigation.
Fresh organic strawberries sold through major retailers were associated with hepatitis A infections in the United States and Canada.
Peanut butter manufactured at a Kentucky facility was linked with a multistate Salmonella outbreak and a broad recall.
Reports of serious Cronobacter infections in infants prompted investigation, plant shutdowns, recalls, and wider scrutiny of powdered formula safety.
Packaged leafy greens were linked to an outbreak of E. coli O157:H7 infections.
