NIAID’s pathogen priority list is periodically reviewed and is subject to revision in conjunction with our federal partners, including the U.S. Department of Homeland Security, which determines threat assessments, and the Centers for Disease Control and Prevention, which is responsible for responding to emerging pathogen threats in the United States.
Are those organisms/biological agents that pose the highest risk to national security, because they:
Examples of Category A priority pathogens:
Are the second highest priority organisms/biological agents, because they:
Examples of Category B priority pathogens:
Are the third highest priority and include emerging pathogens that could be engineered for mass dissemination in the future due to:
Examples of Category C priority pathogens:
One Health is a collaborative, multisectoral, and transdisciplinary approach — working at the local, regional, national, and global levels — with the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment.
One Health is an approach that recognizes that the health of people is closely connected to the health of animals and our shared environment. One Health is not new, but it has become more important in recent years. This is because many factors have changed interactions between people, animals, plants, and our environment.
These changes have led to the spread of existing or known (endemic) and new or emerging zoonotic diseases, which are diseases that can spread between animals and people. Every year, millions of people and animals around the world are affected by zoonotic diseases.
The CDC uses a One Health approach by involving experts in human, animal, environmental health, and other relevant disciplines and sectors in monitoring and controlling public health threats and to learn about how diseases spread among people, animals, plants, and the environment. The CDC works closely with the US Department of Agriculture (USDA), the Department of the Interior (DOI), and other federal agencies to exchange information and coordinate One Health activities across the US government.
In 2017, CDC, USDA, and DOI organized a One Health Zoonotic Disease Prioritization (OHZDP) workshop to further joint efforts to address zoonotic disease challenges in the United States. Participants in the workshop identified eight zoonotic diseases of greatest national concern:
Following this workshop, the House Appropriations Committee Report that accompanied the 2021 Omnibus Appropriations Bill directed CDC to create a national One Health framework to combat the threat of zoonotic diseases and advance emergency preparedness in the United States. The bill also directs the development of a federal One Health coordination mechanism to strengthen One Health collaboration related to prevention, detection, control, and response for zoonotic diseases and related One Health work across the federal government. CDC, USDA, and DOI are currently working together and with other federal partners to create both the framework and the coordination mechanism at the federal level.
On February 7, 2025, the CDC released their Weekly US Influenza Surveillance Report which included mention of the detection of a human infection of influenza A(H1N2) variant virus among an Iowa resident with no direct or indirect contact with swine. The case sought care during the week ending January 18, 2025, was hospitalized, and has since recovered. No secondary cases have been identified among close contacts of the case. This is the first variant influenza virus infection reported among humans in the United States during the 2024-2025 season.
During the 2023-2024 season in the United States, a total of 9 variant influenza virus infections were reported among humans in Colorado [(H3N2)v: 1], Michigan [(H3N2)v: 1], Minnesota [(H3N2)v: 1], Ohio [(H1N1)v: 1], and Pennsylvania [(H1N2)v: 4].
Most dengue cases reported in the 49 continental US states occur in travelers infected elsewhere.
In 2024, the continental US and territories reported 9,255 cases of dengue; most are associated with travel to affected areas (Caribbean, Central America, South America). Of the locally-acquired cases, 5,835 and 195 cases were from Puerto Rico and US Virgin Islands, respectively, with a smaller number from Florida and CA.
As of February 19, a total of 691 dengue cases have been reported across 18 jurisdictions so far in 2025.
Oropouche virus belongs to the Simbu serogroup of the viral genus Orthobunyavirus in the Peribunyaviridae family. The virus was first detected in 1955 in a febrile forest worker in a village in Trinidad and Tobago called Vega de Oropouche, near the Oropouche River. Oropouche virus is endemic to the Amazon basin.
Prior to 2000, outbreaks of Oropouche virus were reported in Brazil, Panama, and Peru. Evidence of animals being infected was also noted in Colombia and Trinidad during this time. In the last 25 years, cases of Oropouche have been identified in many countries, including Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Panama, and Peru. One child was found to be infected in Haiti in 2014.
In late 2023, Oropouche virus was identified as causing large outbreaks in endemic areas and new areas in South America. In June 2024, Cuba reported its first confirmed Oropouche case. For the latest information, see Countries and Territories with Recent or Previous Oropouche Virus Transmission. Currently, there is no evidence of local transmission in the United States.
The majority of people infected with Oropouche virus become symptomatic. The incubation period for Oropouche virus disease is 3–10 days. Typically, disease starts with the abrupt onset of fever (38-40°C) with headache (often severe), chills, myalgia, and arthralgia.
Other signs and symptoms include photophobia, dizziness, retroorbital or eye pain, nausea and vomiting, or maculopapular rash that starts on the trunk and goes to the extremities. Less common symptoms can include conjunctival injection, diarrhea, severe abdominal pain, and hemorrhagic symptoms (e.g., epistaxis, gingival bleeding, melena, menorrhagia, and petechiae).
Symptoms typically last less than a week (2–7 days). However, in up to 60% of patients, symptoms can reoccur a few days or even weeks later. Similar symptoms are reported on relapse.
The symptoms of Oropouche virus disease can be similar to symptoms of dengue, chikungunya, or Zika viruses, or malaria.
Distributed via the CDC Health Alert Network
August 16, 2024, 4:00 PM ET
CDCHAN-00515
The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory to notify clinicians and public health authorities of an increase in Oropouche virus disease in the Americas region, originating from endemic areas in the Amazon basin and new areas in South America and the Caribbean. Between January 1 and August 1, 2024, more than 8,000 cases of Oropouche virus disease were reported, including two deaths and five cases of vertical transmission associated with fetal death or congenital abnormalities. Countries reporting cases include Brazil, Bolivia, Peru, Colombia, and Cuba. In the United States and Europe in 2024, travel-associated cases have been identified in travelers returning from Cuba and Brazil. As testing and surveillance for Oropouche virus disease increase in the Americas, reports of cases from additional countries are expected. This Health Advisory advises on evaluating and testing travelers who have been in impacted areas with signs and symptoms consistent with Oropouche virus infection. It also raises awareness of the possible risk of vertical transmission (e.g., from gestational parent to fetus during pregnancy) and associated adverse effects on pregnancy and highlights prevention measures to mitigate additional spread of the virus and potential importation into unaffected areas, including the United States.
| Total Human Cases* | 108 |
|---|---|
| Neuroinvasive Human Disease Cases | 2 |
| States and Territories Reporting Cases | 6 |
*Total human disease cases include neuroinvasive and non-neuroinvasive disease cases. Neuroinvasive disease occurs when the virus causes inflammation of the brain (encephalitis) or inflammation of the tissues around the brain (meningitis).
Although the likelihood of Oropouche spreading widely in the continental United States is low because of differences in climate, types of biting midges and mosquitoes, and lifestyles (such as the use of air conditioning), some cases may occur in limited areas.
It is unknown how widely Oropouche virus could spread in Puerto Rico and U.S. Virgin Islands.
CDC has interim recommendations for male travelers and all travelers to areas with a Level 1 or 2 Travel Health Notice for Oropouche to prevent possible transmission during sex.
On February 11, 2025, the PAHO/WHO released an epidemiological update regarding Oropouche in the Region of the Americas during 2024 and 2025. According to the report, there were a total of 16,239 confirmed Oropouche cases reported, including 4 deaths, across 11 countries and 1 territory in the Region of the Americas during 2024. Cases were predominantly reported from Brazil (84.9%), Peru (7.8%), Cuba (3.9%), and Bolivia (2.2%). Confirmed cases of vertical transmission were reported in Brazil only (4 cases of fetal death and 1 case of congenital anomaly).
During 2025, there have been a total of 3,765 confirmed Oropouche cases and no deaths reported across 6 countries in the Region of the Americas. Cases have predominantly been reported from Brazil (97.7%) and Panama (2.1%). No cases of vertical transmission have been reported this year.
