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. 2022 Dec;46(4):1090-1102.
doi: 10.1007/s12639-022-01529-8. Epub 2022 Sep 10.

Assessment of schistosomiasis transmission in the River Nile at Greater Cairo using malacological surveys and cercariometry

Hanaa M M El-Khayat  1 , Hanan S Mossalem  1 , Karem El-Hommossany  1 , Sara S M Sayed  1 , Wafaa A Mohammed  1 , Khaled M Zayed  1 , Mohamed Saied  1 , Mohamed R Habib  1
Affiliations

Assessment of schistosomiasis transmission in the River Nile at Greater Cairo using malacological surveys and cercariometry

Hanaa M M El-Khayat et al. J Parasit Dis. 2022 Dec.

Abstract

Continuous field studies on the abundance and distribution of freshwater snails and cercarial populations are important for schistosomiasis control programs. In the present work, snail surveys and cercariometry were conducted for four successive seasons at 12 sites on the Nile River banks in the area of Greater Cairo to identify potential transmission foci for schistosomiasis. In addition, water physicochemical parameters were recorded. The results showed that the electrical conductivity, total dissolved solids, dissolved oxygen, and pH were within the permissible levels, except that the water temperature increased, especially in the spring season. Malacological surveys identified 10 native snail species at the studied sites of the Nile River, namely Bulinus truncatus, Biomphalaria alexandrina, Lymnaea natalensis, Lanistes carinatus, Cleopatra bulimoides, Melanoides tuberculata, Helisoma duryi, Bellamya unicolor, Physa acuta, Thedoxus niloticus, and one invasive snail species, Thiara scabra. The calculated diversity index indicated that the structure of snails' habitats was poor, while Evenness index indicated that the individuals were not distributed equally. Natural infection results identified no schistosome cercariae in B. truncatus and B. alexandrina. However, the cercariometry recovered Schistosoma cercariae in all the surveyed sites during all seasons with variable distribution. The preceding data suggest that there are still some active transmission foci for schistosomiasis infection in the Nile River. Moreover, the present finding highlights the importance of cercariomety as a complementary approach to snail samplings for identifying the transmission foci for schistosomiasis.

Keywords: Biomphalaria alexandrina; Bulinus truncatus; Cercariometry; Schistosomiasis; Snail surveys.

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Conflict of interest statement

Conflict of interestThe authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
A map of Egypt showing the investigated sites on the Nile River
Fig. 2
Fig. 2
Components of cercaiometry apparatus used in the current study
Fig. 3
Fig. 3
Distribution of snail samples collected from the Nile River in the area of Greater Cairo during summer, autumn, winter and spring seasons 2019–2020
Fig. 4
Fig. 4
Diversity and Evenness indices during different seasons
Fig. 5
Fig. 5
The percentage of cercariae detected at investigated sites
See this image and copyright information in PMC

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