Global trends of pandemic-prone and epidemic-prone disease outbreaks in 2024

ABSTRACT

During 2024, the number of pandemic-prone and epidemic-prone disease outbreaks worldwide was estimated at 301. The data highlight a shift in disease outbreak patterns, with a decline in the number of countries reporting public health events of concern linked to COVID-19 and a rise in those reporting outbreaks of viral diseases transmitted by vectors.

About 90% of the outbreaks in 2024 were associated with COVID-19, dengue, yellow fever, Oropouche virus disease and influenza (linked to identified zoonotic or pandemic influenza virus). Although disease outbreaks can affect any country anywhere, they tend to disproportionately occur in countries facing many other socio-economic development, climatic and humanitarian challenges. In this regard, sub-Saharan Africa and the subregion of Latin America and the Caribbean—home to just 23.3% of the world’s population—reported the highest number of disease outbreaks in 2024 with about 57% of the total. Particularly, the sub-Saharan Africa region has been the site of nearly 32% of recorded outbreaks since 1996. Future research should include efforts to improve the quality and availability of disease outbreaks data—particularly in the most exposed or vulnerable regions—and to promote the scientific use of such information for foresight purposes and for forecasting future health events of concern to support anticipatory action.

SUMMARY BOX .

• During 2024, the number of pandemic-prone and epidemic-prone disease outbreaks worldwide was estimated at 301. The data highlight a shift in disease outbreak patterns, with a decline in the number of countries reporting public health events of concern linked to COVID-19 and a rise in those reporting outbreaks of viral diseases transmitted by vectors.

• About 90% of the outbreaks in 2024 were associated with COVID-19, dengue, yellow fever, Oropouche virus disease and influenza linked to identified zoonotic or pandemic influenza virus.

• Although disease outbreaks can affect any country anywhere, they tend to disproportionately occur in countries facing many other socio-economic development, climatic and humanitarian challenges.

• Future research should include efforts to improve the quality and availability of disease outbreaks data and to promote the scientific use of such information for foresight purposes and for forecasting future health events of concern to support anticipatory action.

Standfirst

Juan Armando Torres Munguía and Inmaculada Martínez-Zarzoso consider the quantification of global disease outbreaks essential to better understand health emergencies and to enable anticipatory actions that save lives. This article highlights a post-pandemic shift in outbreak patterns, marked by a 2024 rise in the number of countries reporting viral vector-borne disease outbreaks.

According to the updated global dataset of pandemic-prone and epidemic-prone disease outbreaks,^{1 2} an estimated 301 outbreaks occurred worldwide in 2024. While this figure represents an 18.3% drop from 2023, it still surpasses pre-pandemic levels. In 2019, 1 year before the onset of the COVID-19 pandemic, 95 disease outbreaks were reported globally, compared with 159 recorded in 2024, excluding COVID-19.

This article aims to analyse where and which diseases occurred globally during 2024. Beyond describing these patterns and trends, the ultimate purpose is to strengthen understanding of the current dynamics of disease outbreaks and to generate evidence that can support epidemiological research, inform anticipatory risk assessments and guide actions aimed at reducing preventable illness and deaths. Providing systematic and comparable analyses of outbreak data is essential for identifying emerging trends, improving early-warning capacities and contributing to more effective preparedness for future health threats.

To achieve the abovementioned objectives, after introducing the data, the article explores three key questions: Where are outbreaks occurring? Which diseases are driving these outbreaks? and How are these outbreaks embedded within the context of socio-economic development, climatic and humanitarian challenges?

About the data

The global dataset of pandemic-prone and epidemic-prone disease outbreaks was initially conceptualised by a team of researchers from the University of Göttingen, the University of Groningen and the University of Bordeaux to address the need for open and reliable statistical information on public health events of concern, ensuring methodological rigour for research purposes.¹

This dataset draws on two distinct sources from the WHO: the Disease Outbreak News for all non-COVID-19 outbreaks, and the coronavirus dashboard for COVID-19-related data.¹ Since the launch of the original version in 2022, the information has been continuously updated and currently documents more than 3200 outbreaks across over 230 countries and territories from January 1996 to December 2025. To transform the unstructured records to an accessible, open, global dataset, the authors developed scripts in R to extract, clean, organise, reshape and classify the information. These scripts are fully available at https://github.com/jatorresmunguia/disease_outbreak_news for transparency and reproducibility purposes. The global dataset is also part of the Humanitarian Data Exchange initiative of the United Nations Office for the Coordination of Humanitarian Affairs and can be downloaded at: https://data.humdata.org/dataset/global-pandemic-and-epidemic-outbreaks.

It is important to note that the unit of analysis in this dataset is an outbreak. Although there are different definitions of an outbreak,³ in accordance with the original dataset, an outbreak is defined in this paper as the occurrence of at least one case of a specific disease in a country or territory during a given year. Therefore, a country or territory cannot have multiple outbreaks of the same disease within the same year, though it may experience outbreaks of different diseases. A country can only have multiple outbreaks of the same disease if they occur in different years.¹ While this definition may represent a caveat, the original sources do not provide sufficient temporal details to determine the start and end of each health event. However, this definition avoids introducing bias related to reporting frequency, which could primarily reflect countries’ surveillance and reporting capacities rather than the actual occurrence of events. It is essential for readers to keep this in mind when reviewing this document and interpreting the figures.

Disease outbreaks by region

The geographical distribution of disease outbreaks in 2024 showed a marked variation across continents. As depicted in figure 1, Africa and the Americas reported the highest number of outbreaks (90 each), followed by Asia (49), Europe (45) and Oceania (27). Compared with the previous year, all continents experienced a decline in the number of reported outbreaks except Oceania, where outbreaks increased from 23 to 27.

Figure 1. Geographical distribution of disease outbreaks in 2024.

Note: this map follows the classification of geographical regions used by the Statistics Division of the United Nations Secretariat.

Within each continent, disparities in the occurrence of disease outbreaks become much more evident than across continents. In Africa, most events were concentrated in sub-Saharan Africa (87 outbreaks), the subregion with the highest number of outbreaks globally in 2024. This pattern is persistent, given that over the 1996–2024 period, sub-Saharan Africa has consistently recorded the highest number of pandemic-prone and epidemic-prone disease outbreaks, accounting for nearly 32.2% of the total events.² Existing evidence points to a marked spatial concentration of outbreaks in this subregion,¹ which underscores the regional recurrent exposure to infectious diseases. Over time, however, the composition of outbreaks in sub-Saharan Africa has evolved. While earlier years were dominated by food-borne and water-borne diseases (such as cholera) and vaccine-preventable infections (including poliomyelitis, measles and meningococcal meningitis), more recent outbreaks increasingly involve vector-borne and zoonotic diseases, notably dengue, yellow fever, Ebola virus disease and monkeypox. Within sub-Saharan Africa, the Democratic Republic of Congo reported 10 outbreaks, the highest number recorded by any country worldwide in 2024, followed by Côte d’Ivoire (4 outbreaks, the second highest globally) and by Kenya, Rwanda, Burkina Faso, Ghana, Ethiopia, Niger, Uganda and Chad (each reporting 3 outbreaks).

In the Americas, the largest number of outbreaks occurred in Latin America and the Caribbean (85 outbreaks). Although this subregion experienced an 18.4% decrease compared with the 103 outbreaks recorded in 2023, it remains one of the most affected areas globally. Brazil reported 4 outbreaks, being the second most affected country worldwide in 2024, tied with Côte d’Ivoire. Several other countries in the Americas also reported relatively high counts, including Bolivia, Colombia, Cuba, Ecuador, Guyana, Mexico, Panama, Peru, the USA and Uruguay, each with 3 outbreaks.

In Asia, the highest numbers of outbreaks were recorded in Southeast Asia (20 outbreaks) and Southern Asia (15), followed by Western Asia (7), Eastern Asia (4) and Central Asia (3). Most affected countries in Asia during 2024 were Bangladesh, Cambodia, China, India (with 3 outbreaks each), and a second group of 10 countries (Afghanistan, Indonesia, Iran, Lao People’s Democratic Republic, Malaysia, Myanmar, Singapore, Sri Lanka, Thailand and Viet Nam), with 2 outbreaks each.

In Europe, levels of disease outbreaks were more homogeneously distributed across subregions. In 2024, Northern Europe registered 13 outbreaks, Western Europe 12, Eastern Europe 10 and Southern Europe 10. At the country level, six countries concentrated most of the events recorded in the region (Sweden with 3 outbreaks; and Denmark, Austria, France, Germany and the Netherlands, with 2 outbreaks each).

In Oceania, the subregion of Polynesia reported 12 outbreaks, Micronesia 6, Melanesia 5 and Australia and New Zealand 4. At the national level, Australia with 3 outbreaks reported the highest number, followed by French Polynesia, the Federated States of Micronesia, New Caledonia, Palau, Samoa, Tonga and Wallis and Futuna, with 2 outbreaks each.

Leading diseases behind the outbreaks

The year 2024 marked a shift in disease outbreak patterns, characterised by a decline in the number of countries reporting public health events of concern linked to COVID-19 and an increase in those reporting outbreaks of viral diseases transmitted by vectors—including dengue, yellow fever and Oropouche virus disease—(see figure 2). In comparison with previous years, from 2020 to 2023, COVID-19 was reported in an average of 218 countries and territories annually, but this number decreased to 142 in 2024, a reduction of approximately 35%. In contrast, vector-borne viral diseases exhibited an increase of 281%, rising from an annual average of 32 affected countries or territories during 2020–2023 to 122 in 2024. As highlighted in previous research,⁴ disruptions in prevention programmes, reduced access to health services and constraints on field operations caused by the COVID-19 pandemic may have contributed to changes in disease outbreak patterns.

Figure 2. Pandemic-prone and epidemic-prone disease outbreaks in the world, 2018–2024.

Note: each □ represents a country. For a detailed breakdown of the diseases included in the ‘Other’ category, see the online supplemental table S1 in the supplementary material.

The top five diseases responsible for outbreaks in 2024 constituted 90% of the total worldwide. In descending order of the number of outbreaks linked to them, these diseases were COVID-19, dengue, yellow fever, Oropouche virus disease and influenza due to identified zoonotic or pandemic influenza virus. Note that in figure 1, the category ‘Other’ refers to a set of low-frequency diseases that were grouped together for analytical clarity.

At a global level, COVID-19 continued to be the most frequently reported disease in 2024, accounting for 47% of all outbreaks in the year. However, its prevalence declined by approximately 32.5% compared with 2023. Across continents, all the regions experienced a decline in the number of reported outbreaks associated with COVID-19 from 2023 to 2024, although with heterogeneous magnitudes. Oceania and the Americas showed the most pronounced reductions (43.5% and 42.9%, respectively), followed by Asia (37.5%), Africa (25%) and Europe (17.8%). A more granular examination of subregions within continents reveals even more pronounced contrasts in the number of COVID-19 outbreaks registered between 2023 and 2024. Latin America and the Caribbean and Southern Europe recorded declines of around 40%, while Western Asia, Northern Africa, Northern America and Melanesia saw reductions exceeding 50%. Sub-Saharan Africa and Southeast Asia experienced decreases of about 19%. In contrast, Eastern Europe was the only subregion reporting an increase in the occurrence of COVID-19 outbreaks from 2023 to 2024 (11%). Notwithstanding the overall decrease in the number of COVID-19 outbreaks, this disease remained a major public health concern, being responsible for the death of almost 67 000 people worldwide during 2024.⁵

Dengue, the second disease with the most outbreaks in 2024, with 95 recorded cases, saw a 58.3% increase from 2023. While the Americas continued to report the largest absolute number of dengue-associated events (46), the most substantial year-on-year increases occurred outside the region. Africa registered two times as many outbreaks as in 2023 (20 outbreaks in 2024), and Asia recorded a 150% rise (15 outbreaks in 2024). Oceania and Europe, which had reported no dengue outbreaks in 2023, detected 13 and 1 outbreaks, respectively, in 2024. At the subregional level, Southeast Asia experienced the largest percentage change, increasing from a single outbreak in 2023 to seven in 2024, with Cambodia, Laos, Myanmar, Malaysia, Singapore and Vietnam newly reporting cases. In sub-Saharan Africa, the number of affected countries more than doubled, from 9 in 2023 to 19 in 2024, with new reported cases in Angola, Benin, Burkina Faso, Eritrea, Ghana, Kenya, Liberia, Mali, Mayotte, Niger, Réunion and Senegal. Several subregions that had not reported dengue outbreaks in 2023—including Polynesia, Melanesia, Micronesia, Australia and New Zealand, Eastern Asia and Western Europe—registered events in 2024. Conversely, Northern Africa and Northern America showed no substantial changes. Latin America and the Caribbean exhibited a relatively modest increase of 4.65%, with additional countries and territories, such as Bonaire Sint Eustatius and Saba, Chile, Cuba, Curaçao and the US Virgin Islands, reporting outbreaks in 2024, after not having reported any in the previous year. Between January and December 2024, the WHO Global Dengue Dashboard reported over 14 million cases of dengue and more than 10 500 associated deaths.⁶

The number of yearly outbreaks related to yellow fever represented 4.3% of all records during 2024. At both the continental and subregional levels, yellow fever outbreaks continued to be concentrated exclusively in Africa, particularly within sub-Saharan Africa. The region recorded a slight increase, rising from 12 outbreaks in 2023 to 13 in 2024. Countries affected by this disease in 2024 were Burkina Faso, Cameroon, Central African Republic, Chad, Congo, Democratic Republic of Congo, Côte d’Ivoire, Guinea, Niger, Nigeria, South Sudan, Togo and Uganda. Yellow fever, a viral disease spread by mosquitoes, leads each year to an estimated 67 000–173 000 severe cases and between 31 000 and 82 000 deaths globally, with Africa accounting for the majority of this impact.⁷

In 2024, events of concern related to Oropouche virus disease were registered in 11 countries and territories, all of them reported in the Americas, particularly in Latin America and the Caribbean. While no outbreaks were reported in 2023, 2024 was characterised by the emergence of this disease in areas where it had not been previously detected, such as Bolivia, Cuba, the USA and Canada.^{8 9}

Influenza due to identified zoonotic or pandemic influenza virus continued with a low but relevant presence. In 2024, approximately 3.3% of the outbreaks were linked to this disease. The countries impacted were Australia, Brazil, China, Spain, Ghana, India, Cambodia, Mexico, the USA and Viet Nam.

Disease outbreaks in the context of armed conflict, climate change and underdevelopment

Although disease outbreaks can affect any country, anywhere, they tend to disproportionately occur in countries facing other development and humanitarian challenges, affecting mostly vulnerable population groups.10,12

Using the Conflict Index developed by the Armed Conflict Location and Event Data Project,^{13 14} countries classified under the low/inactive category recorded the lowest average number of outbreaks per country (1.08). In contrast, countries in the high conflict category recorded the highest average number of outbreaks per country (2.05), followed by those in the turbulent (1.8) and extreme (1.7) categories (table 1).

Table 1. Conflict Index category and disease outbreaks in 2024.

Conflict index category	Total outbreaks	Total number of countries	Average outbreaks per country
Low/inactive	206	190	1.08
Turbulent	36	20	1.80
High	41	20	2.05
Extreme	17	10	1.70

Conflict levels range from lower to higher intensity as follows: ‘low/inactive’, ‘turbulent’, ‘high’ and ‘extreme’. For details, see the online supplemental table S2 in the supplementary material.

The mechanism through which conflict exacerbates the emergence and spreads of disease outbreaks is multifaceted. On the one hand, forced displacement caused by conflicts can increase disease incidence due to poor sanitary conditions in refugee camps and host communities. A recent example is the hepatitis E outbreak in Ouaddai province, Chad.¹⁵ Since April 2023, this region has received a massive influx of refugees and returnees fleeing the conflict in Sudan. Between January and April 2024, 2092 suspected cases of hepatitis E were reported, with 95% occurring in refugees residing in camps and transit sites. On the other hand, limited access to healthcare services in conflict-affected areas hampers disease treatment and containment efforts. In Ethiopia, for instance, more than 7.3 million malaria cases and 1157 deaths were reported between January and October 2024.¹⁶ The country faced significant challenges in delivering essential healthcare due to the destruction and collapse of health facilities in conflict zones. The lack of access to effective treatment and the weakening of the healthcare system exacerbates the crisis, particularly in communities already struggling with food insecurity and other disease outbreaks.¹² It is important to consider that outbreak reporting may be incomplete in conflict-affected settings, where surveillance systems are disrupted, and some regions continue to face structural data gaps that hinder consistent monitoring. These constraints may lead to underestimation of outbreak frequency that should be considered when interpreting the results.

Climate change also plays a crucial role in the emergence and spread of disease outbreaks by altering environmental conditions that favour the transmission of infectious agents.¹⁷ The proliferation and spread of mosquitoes, for example, are heavily influenced by climatic factors such as temperature, humidity and rainfall. Rising temperatures can expand the geographical range of vector-borne diseases by enabling mosquitoes to survive in previously unsuitable regions. Increased humidity and changes in precipitation patterns create breeding grounds that accelerate mosquito reproduction, leading to a higher risk of outbreaks. One of the most frequently recorded diseases in 2024 was the Oropouche virus. According to WHO, its spread has extended beyond its traditional geographical boundaries, driven by a combination of climate change, deforestation and rapid, unregulated urban expansion. These factors have facilitated the virus’s presence in non-Amazonian regions of Brazil and introduced it into countries that had not previously reported cases, including Bolivia and Cuba.^{8 9}

Beyond vector-borne diseases, extreme weather events, such as droughts and floods, also intensify the risk of infectious disease outbreaks by overwhelming healthcare systems and disrupting sanitation services. In the Democratic Republic of Congo, the Panzi health zone of Kwango province is affected by seasonal rains that are expected to increase the incidence of malaria and respiratory infections. While such diseases are common, their mortality rates tend to rise in fragile contexts where healthcare access is limited. Strengthening malaria control efforts, improving clinical management and addressing malnutrition are essential to reducing preventable deaths. However, systemic challenges persist. For instance, shortages of essential medications, financial barriers to healthcare and logistical obstacles, such as poor road conditions and unreliable communication networks, have hindered emergency response efforts. The absence of a functional laboratory in the region further complicates containment measures, as samples must be transported to Kinshasa for analysis, delaying diagnoses and limiting the effectiveness of outbreak responses.¹⁸

A final factor that should be considered is socio-economic development, which plays a critical role in shaping a country’s vulnerability to disease outbreaks. Access to essential infrastructure, including clean water and sanitation, reduces the frequency and severity of outbreaks.¹⁹ A recent analysis of the environmental and globalisation risk factors for disease outbreaks, conducted analysing the global dataset of pandemic-prone and epidemic-prone disease outbreaks, found that improvements in sanitation and drinking water conditions are strongly associated with a lower occurrence of outbreaks.²⁰

Conclusion

Enhancing knowledge of where and how outbreaks emerge is a sine qua non condition for anticipating risks and reducing humanitarian, social and economic costs. By integrating outbreak data with other complementary statistical information, such as environment or humanitarian indicators, future research can move toward identifying the mechanisms that make some regions persistently more susceptible than others.

Finally, it is important to acknowledge that, although the global dataset of pandemic-prone and epidemic-prone disease outbreaks provides only country-level or territory-level aggregates, future efforts should aim to integrate more granular geographical information together with finer temporal detail.

Data availability statement

Data are available in a public, open access repository.