Invasion and Dispersal of Biomphalaria Species: Increased Vigilance Needed to Prevent the Introduction and Spread of Schistosomiasis

Abstract

Biological invasion is a matter of great concern from both public health and biodiversity perspectives. Some invasive snail species may trigger disease emergence by acting as intermediate hosts. The geographic distribution of Schistosoma mansoni depends on the presence of susceptible species of Biomphalaria freshwater snails that support the parasite's transformation into infective stages. Biomphalaria spp. have shown strong local and global dispersal capacities that may increase due to the global warming phenomenon and increases in the development of agricultural and water projects. Should intermediate hosts become established in new areas then this will create potential transmission foci. Examples of snail invasions that have had an impact on schistosomiasis transmission include the introduction of Biomphalaria tenagophila to Congo and B. glabrata to Egypt. The current spread of B. straminea in China is causing concern and needs to be monitored closely. An understanding of the mode of invasion and distribution of these snails as well as their experimental susceptibility to S. mansoni will predict the potential spread of schistosomiasis. Here we review the invasion patterns of Biomphalaria snails and factors that control their distribution and the impact that invasion may have on intestinal schistosomiasis transmission. In addition, we propose some possible surveillance responses for optimum control strategies and interventions. Whenever possible, swift action should be taken to contain any new occurrence of these intermediate snail hosts.

Geographical Distribution of Biomphalaria snails in East Africa

“…(2013) which avers that Biomphalaria snails are less tolerant of temperatures above 27°C. Habib et al . (2021) asserts that temperature is an important factor for Biomphalaria snails’ reproduction and survival and that temperature changes may alter the breeding, survival and distribution of the snails.…”

“…According to Appleton (1978), water velocities have a tendency to sweep Biomphalaria snails from one location to another, mostly during the rainy season. Floods are a bottleneck that has been confirmed to have a direct impact on the availability and distribution of Biomphalaria snails (Habib et al ., 2021).…”

“…Our findings corroborate with a study by Ofulla et al (2013) which avers that B. pfeifferi snails are less tolerant of temperatures above 27°C. Habib et al (2021) asserts that temperature is an important factor for Biomphalaria snails' reproduction and survival and that temperature changes may alter the breeding, survival and distribution of the snails. A positive correlation between water temperature and B. sudanica has also been reported previously (Kazibwe et al, 2006).…”

“…Biomphalaria snails, although not identified to the species level have been collected from Mount Elgon, Rwenzori Mountains and Fort Portal crater lakes (Stanton et al, 2017). B. sudanica snails have also been found in Northern and North Eastern parts of Uganda (Habib et al, 2021).…”

“…B. pfeifferi snails have been found in Uganda at Lwampanga, Masindi Port, Muzizi, Ngamilajojo, Butiaba and Ntoroko (Lake Albert) (Jorgensen et al ., 2007). B. pfeifferi snails have also been found in Northern and North Eastern parts of Uganda (Habib et al ., 2021). In Kenya, B. pfeifferi snails have been found at Muthamo seepage, Matingani seepage, Mbondoni dam, Kangonde dam, Mwea East, Mwea West, Onsando dam, Grogan Canal, Kamayoga stream, Asawo stream, Kwahoma stream and Martin’s drain (Bandoni et al ., 1990).…”