Infectious animal diseases are affecting new areas and species, undermining global food security, human health and biodiversity, according to the first State of the World’s Animal Health report.

The new annual assessment, published by the World Organisation for Animal Health (WOAH), provides the first comprehensive review of animal disease trends, risks and challenges, from the uptake and availability of vaccines to the use of antibiotics in animals. Released ahead of WOAH’s 92nd General Session and its Animal Health Forum — where leading experts will gather to discuss vaccination and innovation in disease prevention — the report sets the stage for high-level discussions on how science-based vaccination strategies and emerging technologies can help address current and future animal health threats through a One Health approach.

Among its findings, the report revealed the reported number of avian influenza outbreaks in mammals more than doubled last year compared to 2023 with 1,022 outbreaks across 55 countries compared to 459 outbreaks in 2023.

The authors highlighted that, while the risk of human infection remains low, the more mammalian species such as cattle, cats or dogs infected, the greater the possibility of the virus adapting to mammal-to-mammal, and potentially -human, transmission.

“The spread, prevalence and impact of infectious animal diseases is changing, bringing new challenges for agriculture and food security, human health and development, and natural ecosystems,” said Emmanuelle Soubeyran, director general of WOAH.

Highly pathogenic avian influenza (HPAI), which has caused the culling or loss of more than 630 million birds in the last two decades, was one of several animal diseases to affect new areas last year.

Peste des petits ruminants (PPR), which has traditionally affected sheep and goats in developing countries, has reemerged in Europe, while African swine fever (ASF) reached Sri Lanka, traveling more than 1,800 kilometers from the nearest outbreaks, the report found.

Almost half of the WOAH-listed diseases notified to WOAH between 2005 and 2023 were considered a threat to human health with zoonotic, or animal-to-human infection, potential.

Vaccination availability not consistent

The report cited climate change and increased trade among the factors influencing the spread and prevalence of animal diseases. Many are preventable through a combination of vaccination, improved hygiene and biosecurity measures; but the report noted that access to animal vaccines remains uneven around the world.

“Alongside other measures, vaccination remains one of the most powerful disease prevention tools available, saving countless lives, preventing economic losses and reducing the need for antimicrobial treatments,” Soubeyran added. “To limit the spread of highly damaging diseases like avian influenza, FMD (foot-and-mouth disease) and PPR, the global community must strengthen international cooperation and ensure equitable access to safe, effective vaccines, alongside other control measures.”

Since 2006, WOAH has supported access to animal vaccines through its vaccine banks and currently operates two, one for rabies and one for PPR. As of May 2025, the WOAH Rabies Vaccine Bank has delivered almost 30 million dog vaccines to countries in Africa and Asia. However, progress toward ending rabies has stalled in recent years, with the percentage of countries reporting implementing control measures falling from 85% to 62%.

The report emphasized the importance of disease prevention for reducing the need for antibiotic treatment and limiting the development of drug-resistant diseases.

By 2050, antimicrobial resistance is projected to cause livestock losses that jeopardize the food security of 2 billion people and result in a $100-trillion (U.S.) economic loss if urgent action is not taken.

The latest figures indicate that antimicrobial use, including antibiotics, in animals fell 5% between 2020 and 2022, with use in Europe seeing the biggest decline of 23%, followed by Africa at 20%. However, one in five countries continues to use antimicrobials as growth promoters, which is discouraged by WOAH.

“The indiscriminate use of antimicrobials contributes to antimicrobial resistance, which is a major threat to both animal and human health,” said Javier Yugueros-Marcos, head of the Antimicrobial Resistance and Veterinary Products Department at WOAH. “The declining use of antibiotics in almost all regions is encouraging, but further reductions can be achieved by prioritizing preventative measures against animal diseases, with vaccination as an essential component of these.”

WOAH calls for investments to strengthen national Veterinary Services, greater global and regional coordination and improved disease surveillance systems to scale up effective disease control. This includes developing and implementing advanced diagnostic tools to differentiate between vaccinated and infected animals, enabling accurate disease tracking and trade transparency.

The report is available online here.