Future-proofing public health: One Health and the SCI
Like many others in the public health community, I was surprised when an outbreak of schistosomiasis, a parasitic worm infection associated with low-income countries in tropical climates, was reported on the French Island of Corsica in 2014.
A few years on, infected freshwater snails that form an essential part of the disease transmission cycle continue to harbour the disease on the island and put those in contact with water bodies at risk of infection.
Another layer of complexity has recently been added to this – the species of parasite found on the island is a “hybrid”: it can lead to two-way transmission between humans and mammals and may even be better at causing infection than the original human or animal species. In this particular case, the parasite seems to have travelled through humans from the west coast of Africa.
The existence of hybrid schistosome species was again highlighted recently by researchers from the Royal Veterinary College, demonstrating that highly infectious human-livestock hybrid parasites are driving the emergence of growth of transmission hotspots in West Africa.
These stories show that parasitic worm infection control, conducted predominantly through mass deworming of the human population in areas at risk, is becoming increasingly more challenging. As the parasites themselves evolve into new forms, treatment strategies will need to adapt to include both the human and livestock population. However, this may be further complicated as hybrid species are increasingly found in other animals such as rats, and global travel and rising temperatures are also likely to influence transmission.
What do these challenges mean for the SCI? As a trained veterinarian who has been working on human public health over the past 10 years, I believe we must be guided by the principle of One Health - a simple concept signifying that healthy people, healthy animals and a healthy environment are inextricably linked and interdependent. Given our focus on parasitic worm infections in low-income settings, the SCI plans to address two main aspects:
The risks to human health of animal or human-animal parasite species that can infect humans.
The risks to livelihoods of the 70% of the world’s poorest people who rely on animal growth and productivity, which can be affected by parasitic worm infections.
In the countries supported by the SCI, humans and animals commonly live in close proximity in rural households, further increasing the risk of disease transmission. However, given the dependence of rural livelihoods on animals, disease control measures such as veterinary services or altering farming practices to decrease human-animal contact may be too costly for low-income households and therefore raise challenges for implementation.
A comprehensive approach driven by One Health can take into account communities’ needs and social and cultural context, while providing a framework for collaboration between healthcare services, veterinary public health services and environmental programmes including water, sanitation and hygiene. This will deliver greater impact to all sectors.
This is why the SCI has adopted a One Health approach that goes beyond treatment of parasitic worms. Our approach aims to change population behaviour to reduce transmission between humans and between human and animal populations, address environmental transmission factors, and increase access to all basic services including healthcare, water, sanitation and education. In this way, we hope to be able to respond more readily to a changing public health landscape.
Dr Wendy Harrison