Controlling Schistosomiasis Parasites By Learning How To Kill Snails
A Science Enthusiast
Gruesome conditions brought on by bacteria, viruses, and, often the most directly disgusting of all, parasitic organisms.
Neglected Tropical Diseases: Schistosomiasis
Schistosomiasis is one of these and is listed as a neglected tropical disease (NTD), a category of diseases that primarily affect the poorest among us across places like Africa, Central and South America, and Southeast Asia. Leading to dangerous infections of the lower intestine and organ damage, schistosomiasis is caused by a parasite known as blood flukes. They are transmitted via fresh water sources and can infect a person either from them drinking said water or by bathing in it, where the flukes can then have access to infect a person’s urinary tract.
Hundreds of millions of people around the world are afflicted with schistosomiasis and around 200,000 die every year from it. Due to this, the World Health Organization has placed the disease on an official action watchlist, with the goal of eradicating it by 2025. But this is not an easy task to undertake.
While there are medicines that can be consumed to lower the risk of infection and also better infrastructure can be built to increase the availability of clean freshwater sources, this will not completely remove schistosomiasis from the world. The other primary business at hand to ensure this outcome is to target the main host species that the blood flukes use as vectors before infecting humans: freshwater snails.
Understanding A Snail
Of those, Biomphalaria glabrata is the species that causes the most infections, along with its cousin species. The blood flukes take over the snail, make it unable to reproduce, and cause it to begin creating thousands of the next form of the parasite’s life cycle, which then lets it travel openly through freshwater to infect humans.
A team of over 100 researchers from around the world came together to sequence and characterize the genome of this snail species in order to better understand its role within the blood fluke’s life cycle. Due to their persistence and resilience, this snail and the others in its genus have been recognized as invasive species that spread rapidly. They often destroy natural ecosystems in the process in addition to spreading disease.
The researchers want to find out genetic keys to the snail’s resistance to chemical efforts to kill them, along with ways to influence their immune system and gene regulation processes. After conducting a full genome sequencing and genomic deep dive, they found several options they wish to employ against the snails.
A Slew Of Genetic Tools
One of the first things they discovered was that the Biomphalaria genus in general are all capable of being hosts for the blood flukes, meaning all the species therein have to be dealt with in some manner. For the species that are the vital ones to watch in third world countries , however, B. glabrata serves as a useful template, matching more than 90% of its sequence traits with its cousin, B. pfeifferi, that spreads schistosomiasis in Africa.
Another discovery is how the snails use pheromones in order to find mates. These have the potential to be altered and make it so that the snails have severe reductions in reproduction rates due to an inability to properly find others of their species. This could also impact the spread of the blood flukes through the snail population, driving down infection rates two-fold.
A third option is to use the newly understood genetics to tailor chemical products that directly turn off particular genes of the snail’s, whether for reproduction or metabolism to kill them. Lastly, there is the option to genetically alter the snails in order to prevent them from being able to be infected with blood flukes in the first place.
For the sake of the species, the latter is a preferable option, but for the sake of human lives and the WHO’s goal timeline, it may not be feasible in a reasonable amount of time. Either way, all of the above serve as new options for scientists to begin investigating in more depth and a combination of them is likely to be used, along with medication and infrastructure work.
A combined effort will hopefully lead to a success in the WHO’s goal of eradicating schistosomiasis by 2025 or close enough. In the process, hundreds of thousands of lives will be saved and countries given new access to clean water. The latter itself will likely improve the health of so many more.
For now, biotechnology researchers continue the fight against our world full of diseases, one step at a time.
Photo CCs: Schistosoma 20041-300 from Wikimedia Commons