Scientists at the Kenya Medical Research Institute (Kemri) say they have found an invasive exotic freshwater snail wreaking havoc in rice farms and putting people at risk of meningitis.
The snail is believed to have arrived in the country in 2020 from South America but it is still unknown how it landed here though experts suspect that someone brought it.
Known as Pomacea canaliculata, it’s also blamed for causing human eosinophilic meningitis.
Dr Martin Mutuku, the principal investigator and a senior research scientist at the Centre for Biotechnology Research and Development (Kemri), explained that the snail is considered a devastating agricultural and ecological pest as well as a threat to rice farming in Mwea Irrigation Scheme, Kirinyaga County, and wetlands biodiversity in the country apart from being a potential public health threat.
“The million-dollar question is how did the snail get here? Farmers told us that it feeds on young rice seedlings during the planting season. It causes meningitis in humans when it gets to the brain as the parasite gets lost in there,” he told Daily Nation.
According to the findings, P. canaliculata serves as intermediate host of the rat lungworm, Angiostrongylus cantonensis, which causes human eosinophilic meningitis, an emerging disease.
Long term impact of this snail in Kenya remains unknown.
“Sampling was done using a standard snail scoop in 15 streams, four ponds and four canals within the Mwea rice irrigation scheme. The snails and snail egg masses collected were transferred into plastic containers, and identified using snail taxonomic keys based on morphological features, with the aid of a dissecting microscope. The presence of a thriving population of P. canaliculata in the Mwea irrigation canals, ponds and rice paddies was confirmed, and numerous Pomacea egg masses also observed,” the findings state.
The team of researchers also interestingly found that another snail that exists in the country which causes Bilharzia has drastically reduced in number due to the arrival of the new snail.
“Only two canals located on the upper periphery side of the irrigation scheme were found to be having Biomphalaria Pfeifferi snails, most likely they may be competing for resources; we are still investigating,” Dr Mutuku said.
According to the Global Invasive Species Database, also known as miracle snail, the freshwater snail has a voracious appetite for water plants including lotus, water chestnut, taro and rice.
“Introduced widely from its native South America by the aquarium trade and as a source of human food, it is a major crop pest in south east Asia (primarily in rice) and Hawaii (taro) and poses a serious threat to many wetlands around the world through potential habitat modification and competition with native species,” experts say.
Dr Mutuku said although they are currently investigating whether the snail has spread to other parts of the country, there is an urgent need for a multisectoral approach in dealing with the invasive species, an approach that will involve the ministries of Agriculture, Water and Health.
“ Remember two main rivers flow from Mt Kenya to Kirinyaga after which River Sagana flows into Tana River and the water goes all the way into the coastal region and, therefore, they will spread to other parts of the country,” he said.
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