Climate Change Is Fueling New Threats — and We’re Not Ready

As part of a conference focused on the One Health approach, Liège Créative, a forum established by the University of Liège, Liège, Belgium, to foster interdisciplinary collaboration and networking, invited two researchers with distinct but interconnected areas of expertise to examine the impact of climate change on health. 

Dominique Votion, DVM, PhD, associate professor at the Faculty of Veterinary Medicine at the University of Liège, discussed the effects of invasive plants on horses and humans, while Gilles Darcis, PhD, from the Department of Infectious and Parasite Diseases of the university, explored the risks posed by vector-borne diseases.

“One Health recognizes the interconnectedness of human, animal, plant, soil, forest, and ocean health. This interdisciplinary and cross-sectoral approach aims to view health as a whole,” explained Nicolas Antoine-Moussiaux, DVM, PhD, One Health coordinator at the University of Liège.

From this perspective, the two speakers addressed the health consequences of climate change on both humans and animals. Votion focused on how rising temperatures influence the spread of invasive plants.

Senecio: A Public Health Concern?

Certain plants become toxic as a result of climate change. For example, sorghum can be fatal to horses when grown under drought conditions. Other plants are inherently toxic and are spreading more rapidly due to climate shifts, such as Senecio spp.

“Invasive plants threaten the three pillars of One Health. They disrupt biodiversity by overtaking ecosystems, pose risks to herbivores, and harm humans through direct contact or consumption of contaminated food,” explained Votion. She is particularly concerned about the proliferation of Senecio, which contains pyrrolizidine alkaloids. These hepatotoxic compounds are especially dangerous for horses but also pose a risk to human health.

“Humans can ingest pyrrolizidine alkaloids directly, such as through tea. These compounds have also been detected in honey from bees that foraged on Senecio and in the milk of cows that consumed contaminated forage,” she explained.

The health risks of Senecio exposure are varied and severe, including irreversible liver failure, cancer, hypertension-related conditions, and lung damage. Although Sciensano, Belgium’s national public health institute, is taking the risk seriously, Votion fears that the extent of this public health issue is being underestimated.

“Acceptable limits for pyrrolizidine alkaloids, which are found in plants beyond Senecio, have been raised in recent years. Sciensano is developing analytical methods to screen food products more effectively. However, the main issue is that intoxication occurs gradually over time. Clinical symptoms may take a long time to appear, and by the time they do, the damage may already be irreversible,” warned Votion.

Mosquitoes and Vector-Borne Diseases

Darcis examined the potential impact of climate change on vector-borne diseases, including malaria, dengue, Zika, and chikungunya. He emphasized the complexity of predicting these effects, given the numerous factors involved.

“Climate change influences the pathogen, the vector, the non-human reservoir, and humans. With so many interacting variables, it is impossible to create perfectly accurate predictive models. Additionally, these studies shape policy decisions, which in turn can distort the models themselves,” he explained.

Darcis then focused on mosquitoes — the deadliest animal in the world — which are responsible for more than 700,000 deaths annually, including over 600,000 from malaria. Contrary to common belief, water-related environmental changes, rather than air temperature alone, have the greatest impact on mosquito survival and reproduction.

“One might assume that increased rainfall would favor mosquito populations, but in reality, they thrive during droughts. Water shortages lead to water storage in containers, which provide ideal breeding grounds for mosquitoes,” Darcis noted.

As a result, in Africa, prolonged droughts are linked to an increase in mosquito-borne diseases. Each mosquito species has an optimal temperature range for survival. The Anopheles mosquito, responsible for malaria transmission, is most active at 25 °C.

“With climate change, we can expect this mosquito to migrate from West Africa and the Democratic Republic of Congo to higher-altitude regions such as Ethiopia, which has so far been relatively unaffected,” Darcis predicted.

The tiger mosquito, a vector for dengue, Zika, and chikungunya, thrives at around 30 °C.

“There is growing concern that dengue cases in Africa will surge in the second half of the century unless a vaccine is developed and widely distributed before then,” he added.

Tiger Mosquito in Europe

Rising temperatures are enabling the expansion of the tiger mosquito into temperate regions. First detected in mainland France in 2004, it is now firmly established across the country.

“This has led to a sharp increase in autochthonous dengue transmission, particularly in southern France, but also in the Paris region. Last year, we even recorded the first locally transmitted case of chikungunya in the French capital,” Darcis said.

The tiger mosquito has also settled in Belgium. “A few years ago, we assumed it was migrating north from southern France via transport routes. However, we now know it is established locally because we find it in the same locations year after year,” he explained.

At present, the tiger mosquito population in Belgium remains too small to trigger outbreaks of dengue or chikungunya, but experts believe this could change in the near future. Sciensano is closely monitoring the situation and has launched public awareness campaigns to reduce transmission risks.

Vector Control

“As with any infectious disease, the focus is often on eradicating the vector. This is the approach taken with the tiger mosquito. While I understand the rationale, I find it frustrating because it prevents a broader discussion about climate change and its consequences,” said Darcis.

“We continue to be reactive instead of proactive. Additionally, I’m not convinced that these eradication campaigns are effective in the long run. We also don’t fully understand their broader ecological impact. Are we actually making the problem worse when viewed through the lens of One Health?” he concluded.

This story was translated from MediQuality using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.