Biomphalaria alexandrina in Egypt: Past, present and future

Abstract

The African species of Biomphalaria appeared as a result of the relatively recent west-to-east trans-Atlantic dispersal of the Biomphalaria glabrata-like taxon. In Egypt, Biomphalaria alexandrina is the intermediate host for Schistosoma mansoni. Biomphalaria alexandrina originated in the area between Alexandria and Rosetta and has historically been confined to the Nile Delta. Schistosoma mansoni reached Egypt via infected slaves and baboons from the Land of Punt through migrations that occurred as early as the Vth Dynasty. The suggestion of the presence of Schistosoma mansoni infection in Lower Egypt during Pharaonic times is discussed despite the fact that that there is no evidence of such infection in Egyptian mummies. It is only recently that Biomphalaria alexandrina colonized the Egyptian Nile from the Delta to Lake Nasser. This change was likely due to the construction of huge water projects, the development of new water resources essential for land reclamation projects and the movement of refugees from the Suez Canal zone to the Delta and vice versa. The situation with respect to Biomphalaria in Egypt has become complicated in recent years by the detection of Biomphalaria glabrata and a hybrid between both species; however, follow-up studies have demonstrated the disappearance of such species within Egypt. The National Schistosoma Control Program has made great strides with respect to the eradication of schistosoma; however, there has unfortunately been a reemergence of Schistosoma mansoni resistant to praziquantel. There are numerous factors that may influence the prevalence of snails in Egypt, including the construction of water projects, the increase in reclaimed areas, global climate change and pollution. Thus, continued field studies in addition to the cooperation of several scientists are needed to obtain an accurate representation of the status of this species. In addition, the determination of the genome sequence for Biomphalaria alexandrina and the use of modern technology will allow for the study of the host-parasite relationship at a molecular level.

Climate Change and Water-Related Infectious Diseases

“…Increases in parasite growth related to temperature can be offset by increased snail mortality at higher temperatures [127]. Schistosoma eradication campaigns may be impacted by changes in snail distribution, migrant workers and weather [128]. The impact of water and sanitation on schistosomiasis has shown that access to safe water and adequate sanitation is important in reducing schistosomiasis [129,130].…”

New diagnostic tools in schistosomiasis

“…large dams and irrigation systems) are key risk factors for the spread and intensification of schistosomiasis [1]. Climate change is likely to exacerbate transmission or extend the disease further north or into higher altitudes [10][11][12][13][14][15]. High mobility of people and migration bear the risk of (re-)introducing schistosomiasis transmission into areas that had been considered to be non-endemic or that managed to locally eliminate the disease, despite the presence of intermediate host snails [16].…”

Control of infection of Biomphalaria alexandrina (Ehrenberg, 1831) with Schistosoma mansoni Sambon, 1907 using Eucalyptus camaldulensis

“…This prevalence rate is considerably higher than expected and has many indications. For example, it may indicate a recent human-water contact in spots with abundant occurrence of infected Biomphalaria alexandrina (Ehrenberg, 1831), the main intermediate host for S. mansoni in Egypt (lotFy et al 2005, MoHaMed et al 2012, abou el-naGa 2013. Thus, efforts should be directed to identifying such spots and to take appropriate measures.…”