What is the economic impact of schistosomiasis? A One Health question.

A recent study in Senegal examines the financial impact of schistosomiasis in cattle, highlighting that loss of income and decline in productivity are the result of human and cattle schistosomiasis. A One Health approach is needed to understand the true socioeconomic impact of schistosomiasis and to help design coordinated, multisectoral elimination efforts.

Schistosomiasis, health and socio-economic impact.

Schistosomiasis is a debilitating and largely hidden parasitic disease, one of the neglected tropical diseases that the WHO aims to eliminate by 2030. This blood-borne parasitic worm is considered both a waterborne and vector-borne disease: the transmission occurs in the water where the aquatic snail intermediate host lives and amplifies the parasitic worm. It’s a complex but hugely successful life cycle, with more than 200 million people affected worldwide. If left untreated, the consequences of schistosomiasis can be painful, stigmatizing and dangerous. Intestinal schistosomiasis can lead to liver failure, and urogenital schistosomiasis can lead to bladder cancer, genital damage with increased risk of HIV and infertility. Schistosomiasis is also a disease of veterinary importance, morbidity in livestock can be severe and lead to loss of meat, milk and reproductive opportunities.

African schistosomiasis life cycle. Credit Bonnie Webster at the Natural History Museum, London

Human and animal schistosomiasis can lead to loss of income and reduced productivity. A One Health approach is needed to understand the true socioeconomic impact of schistosomiasis and to help design coordinated, multisectoral elimination efforts. And the benefits could be significant.

Human schistosomiasis and national GDP

A report by the Economist Intelligence Unit and The End Fund found that the economic gains from eliminating morbidity and mortality from human schistosomiasis and soil-transmitted helminthiasis (STH) in Ethiopia, Kenya, Rwanda and Zimbabwe by 2030 could boost these countries. GDP of US$5.1 billion in Purchasing Power Parity (PPP) by 2040. He also indicated that the elimination of health problems associated with human schistosomiasis and soil-transmitted education in these countries could improve their ability to learn and attend school. Their estimates suggest that this could potentially benefit these children by $1.2 billion (PPP) in additional wages between 2021 and 2040 once they enter the workforce.

Water and economic development projects

Human schistosomiasis should be considered when designing water resources and economic development projects, such as large-scale irrigation projects to increase food security and agricultural productivity. If these projects underestimate the risk of schistosomiasis, their investments may backfire, leading to schistosomiasis outbreaks, with farmers close to these projects experiencing lost productivity instead of increased desired economic benefits. This was recently highlighted in a post by Rinaldo et al 2021 examining the economic impact of schistosomiasis in Burkina Faso, where researchers showed that economic returns from water resource development projects were significantly reduced once the health effects of schistosomiasis were taken into account: villages located near large-scale dams suffer an average yield loss of about 20%. Furthermore, the authors found that eliminating schistosomiasis in Burkina Faso would increase average crop yields by about 7%, reaching 32% for clusters with high infection. Read the author’s blog here to learn more about this study.

Cattle schistosomiasis

Recently, a study by Adeyemo et al 2022 assessed the financial impact of schistosomiasis in livestock on farmers in Senegal and developed a baseline of losses and expenses due to schistosomiasis in subsistence and transhumance agriculture. The authors report that schistosomiasis in cattle is a known problem for herders in the 12 villages studied, with herders describing clinical signs of potential schistosomiasis infections in their herd, such as weight loss, hollowness around the eye and diarrhea. Farmers said they would seek local veterinary advice, with some saying they had treated schistosomiasis. The authors modeled two scenarios; scenario one, where farmers test and treat their livestock for schistosomiasis and scenario two where there are no testing or treatment options. The models showed that in the second scenario, the cost to farmers was substantial, reducing the farmer’s livelihood and potentially leading to a situation where basic needs cannot be met.

A health

Schistosomiasis is caused by a number of species of schistosome parasites, infecting different animal hosts, including humans. Some of these schistosomes are incredibly adept at infecting multiple species, such as S. japonicum which can infect over 40 mammalian hosts, and others have the ability to infect different hosts to form zoonotic hybrids, for example between cattle and human schistosomes, S.bovisS.haematobium respectively, as highlighted in this blog post. In communities where livestock and humans live in close proximity and frequent the same water sources, zoonotic schistosomiasis is a significant challenge to human schistosomiasis elimination efforts. In addition, water development projects that do not sufficiently mitigate schistosomiasis could result in an outbreak or increase of this debilitating disease in the very populations they aim to support, leading to reduced economic returns from projects and investments, as well as an increased burden on communities and ministries of health to expend already limited resources to control schistosomiasis infections.

Schistosomiasis affects human health, agricultural production, labor productivity and school performance. The ability of some species to form hybrids and expand host species ranges means that there are zoonotic implications for this disease, but also that a holistic approach including interventions targeting schistosomiasis in cattle could have positive effects. beneficial to human health. Authors at Adeyemo et al 2022 also highlights that with the lack of testing and treatment for livestock and the potential availability of praziquantel donations for humans, farming families may have to choose to treat their herd and protect their food and income. , rather than their own health. Besides the health implications, it also increases the risk of parasite resistance to the only drug known to be effective against all species of schistosomes. A coordinated One Health and multi-sectoral approach could address all of these aspects, benefiting communities by protecting human and animal health, safeguarding investments in water development and increasing productivity and economic development.

So what is the true economic impact of schistosomiasis? Only a One Health approach can answer this question.

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