Habitats of Bulinus truncatus and Planorbarius metidjensis, the intermediate hosts of urinary schistosomosis, under a semiarid or an arid climate

Abstract

Since Bulinus truncatus and Planorbarius metidjensis are the intermediate hosts of Schistosoma haematobium in southwestern Morocco, five rivers were investigated to identify sites colonized by either of both species and determine the characteristics of their habitats via the study of 12 physicochemical parameters in running water. P. metidjensis was observed in the upper valleys of three rivers, whereas B. truncatus was found in sites of lower altitude. A component analysis demonstrated that altitude (from 4 to 1,380 m), water pH (from 5.9 to 9.2), and electric conductivity (from 120 to 6,020 microS/cm) were the main descriptors of environment. A multiple correspondence analysis showed that P. metidjensis was associated to Ancylus fluviatilis, high altitude, and possibly low electric conductivity. B. truncatus was associated to Melanoides tuberculata and was found in lower altitude sites with medium electric conductivity in water. Using logistic regressions, the main characteristics were altitude and dissolved oxygen for B. truncatus, and chlorides and CaCO3 for P. metidjensis. As the habitats of both S. haematobium intermediate hosts differed from each other by altitude and the frequency of snails, which cohabited with them, these findings may be used to detect the presence of either of both intermediate hosts in numerous spring heads which are present on the western slope of the Anti Atlas mountains and the corresponding valleys.

New location for <em>Bulinus truncatus</em> (Audouin, 1827) (Gastropoda: Planorbidae) intermediate host of <em>Schistosoma haematobium</em> and its distribution in the Iberian Peninsula

“…2). These conditions are very similar to those populations studied by Yacoubi et al (2007). Known distribution (Fig.…”

Thermodynamics of cercarial survival and metabolism in a changing climate

“…The molluscan intermediate host in this region is Planorbarius metidjensis . In general, this snail aestivates in the muddy banks of dried up water-courses during the hot summer months, interrupting the parasite's life cycle (Ramjo-Martin and Simon-Vincente, 1988; Yacoubi et al 2007). Consequently, a transmission window exists only during the autumn and spring months when temperatures are cooler and thus S. bovis cercariae would appear to demonstrate thermostability at temperatures that most closely reflect climatic conditions during these seasons.…”

Study of the behavior of snails intermediate hosts of Schistosoma spp. under different maintenance conditions and their resistance to salinity in an african laboratory environment

“…In this study, the ammonium, nitrite and chloride ions were found at variable concentrations in all types of water In addition according to the manufacturer, calcium, bicarbonate and sulfate ions were present in the commercial mineral water with a relatively low conductivity compared to well water and ground pump water. These essential mineral compounds also found in snail breeding sites may have different impact on their development and abundance depending on snail species ( Bakhoum et al., 2019 ; Yacoubi et al., 2007 ). Their absence or low level concentration in distilled water could explain the high and earlier mortality of B. pfeifferi and B. senegalensis observed in the distilled water, unlike what is observed with B. truncatus .…”

“…Moreover, in the delta of the SRB, the population density of this species is higher in areas with lower salinity ( Bakhoum et al., 2019 ). On the other hand, such laboratory research could help to better understand snail population dynamics and preferred habitat, predict their behavior to global environmental change ( Yacoubi et al., 2007 ) and develop control measures such as those attempting to control cercariae through water chlorination ( Braun et al., 2020 ).…”