According to a new study, shrimp aquaculture could not only help develop emerging economies but also protect the populations most vulnerable to schistosomiasis or “snail fever”.
At present, schistosomiasis, commonly known as bilharziasis or “snail fever” from the name of the contaminating animal, affects approximately 250 million people a year worldwide and kills up to 200,000 in the same time lapse. This makes it the second most devastating parasitic disease after malaria. It is most often spread when one comes into contact with contaminated water. Although drugs are available to treat the sick, sometimes they are not effective enough. Furthermore, since the treatments only take into account the human component of the parasite transmission cycle, treated patients can be infected again shortly afterwards.
However, researchers at the University of Berkeley, California (USA), believe they have found a solution. The latter would reside in… shrimps. In a study published on July 8 in the journal Nature Sustainabilitythey developed a roadmap for how freshwater shrimp farming could not only reduce the multiplication of freshwater snails that transmit the worm that causes schistosomiasis, but also improve the economy of the poorest populations, more likely to contract this disease.
Around the world, freshwater shrimp are already farmed in aquaculture systems (term used to describe the culture of aquatic organisms). In the latter, the shrimp are born in hatcheries, then are stored in nurseries before growing up in ponds where bilharzia can be transmitted. Indeed, as they grow, the shrimp feed on snails carrying the parasite, which they love. However, the latter cannot infect them and schistosomiasis is not transmitted by ingestion. Therefore, raising, harvesting and eating shrimp is absolutely risk-free.
“Maximize profit while having a substantial impact on disease reduction”
“River shrimp are common aquaculture products around the world, and we know that these organisms are voracious predators of snails that transmit schistosomiasis,” says Christopher Hoover of UC Berkeley who led the study. “What was unclear was whether we could link the economic benefits of shrimp aquaculture to the disease control activity of shrimp,” he said.
After developing an economic and epidemiological model to try to determine the best areas to store shrimp, the researchers found that the introduction of native shrimp into contaminated waterways was comparable to large-scale drug administration. against schistosomiasis and could reduce the parasite load to almost zero after 10 years. Shrimp may also have environmental benefits, the study argues. They could indeed replace chemical pesticides to control snail populations and restore native biodiversity in areas where they have been decimated by dams.
“We can imagine systems to maximize profit while having a substantial impact on disease reduction, potentially helping emerging and developing economies,” Hoover said.
92% of those infected would live in Africa
“Christopher’s research is a new tool for our global efforts to control schistosomiasis,” adds Justin Remais, co-author of the study. “Poverty and schistosomiasis are intrinsically linked and transmission of the parasite stunts the growth and cognitive development of children and prevents adults from working, thus reinforcing poverty. By targeting the transmission of the parasite itself, while supporting a system locally sourced production where economic benefits flow back to the community, this approach has considerable potential to complement ongoing disease control strategies that typically rely on drug treatment alone,” he concludes.
Indeed, the area of prevalence of bilharzia is located in tropical and subtropical regions, “especially in poor communities that do not have access to safe drinking water and satisfactory sanitation”, according to the World Health Organization (WHO)). At least 92% of people in need of treatment for schistosomiasis live in Africa.
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