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Andrus PS, Joof E, Wade CM. Differentiation of Bulinus senegalensis and Bulinus forskalii Snails in West Africa Using Morphometric Analysis. Acta Parasitol 2024; 69:1016-1026. [PMID: 38502474 PMCID: PMC11001693 DOI: 10.1007/s11686-024-00830-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 02/26/2024] [Indexed: 03/21/2024]
Abstract
PURPOSE Accurate identification of medically important intermediate host and vector species is crucial for understanding disease transmission and control. Identifying Bulinus snails which act as intermediate host species for the transmission of schistosomiasis is typically undertaken using conchological and genital morphology as well as molecular methods. METHODS Here, a landmark-based morphometric analysis of shell morphology was undertaken to determine its utility to distinguish the closely related and morphologically similar sister species Bulinus senegalensis and Bulinus forskalii. The method was developed to increase the accuracy of conchological morphology methods to identify Bulinus species in the field. Both species are found in West Africa, but only B. senegalensis is implicated in the transmission of urogenital schistosomiasis. RESULTS We found when scaled down to the same length, 3-whorl and 4-whorl (juvenile) B. senegalensis shells had a longer spire, narrower body whorl and shorter aperture than B. forskalii. In contrast, 5-whorl (adult) B. senegalensis had a shorter spire, but still had a shorter aperture and narrower body whorl than B. forskalii. Canonical Variate Analysis (CVA) showed minimal overlap between B. senegalensis and B. forskalii for 3-whorl and 4-whorl shells, with a clear separation for 5-whorl shells. Overall, B. senegalensis had a consistently shorter aperture size and narrower body whorl than B. forskalii for all development stages. Spire length was variable depending on the stage of development, with 3-whorl and 4-whorl shells having the opposite trends of adult shells. CONCLUSIONS Our study demonstrates the applicability of landmark-based morphometrics in distinguishing the medically important, Bulinus senegalensis from its morphologically similar sister species, Bulinus forskalii. We recommend using measurements based on spire length, penultimate whorl length, body whorl width and aperture size to differentiate B. senegalensis and B. forskalii, when used with the appropriate information for each shell's development stage.
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Affiliation(s)
- Peter S Andrus
- School of Life Sciences, University of Nottingham, NG7 2RD, Nottingham, UK
| | - Ebrima Joof
- School of Life Sciences, University of Nottingham, NG7 2RD, Nottingham, UK
| | - Christopher M Wade
- School of Life Sciences, University of Nottingham, NG7 2RD, Nottingham, UK.
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Nwoko OE, Manyangadze T, Chimbari MJ. Spatial and seasonal distribution of human schistosomiasis intermediate host snails and their interactions with other freshwater snails in 7 districts of KwaZulu-Natal province, South Africa. Sci Rep 2023; 13:7845. [PMID: 37188748 DOI: 10.1038/s41598-023-34122-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/25/2023] [Indexed: 05/17/2023] Open
Abstract
The spatial and seasonal distribution, abundance, and infection rates of human schistosomiasis intermediate host snails and interactions with other freshwater snails, water physicochemical parameters, and climatic factors was determined in this study. A longitudinal malacology survey was conducted at seventy-nine sites in seven districts in KwaZulu-Natal province between September 2020 and August 2021. Snail sampling was done simultaneously by two trained personnel for fifteen minutes, once in three months. A total of 15,756 snails were collected during the study period. Eight freshwater snails were found: Bulinus globosus (n = 1396), Biomphalaria pfeifferi (n = 1130), Lymnaea natalensis (n = 1195), Bulinus tropicus (n = 1722), Bulinus forskalii (n = 195), Tarebia granifera (n = 8078), Physa acuta (n = 1579), and Bivalves (n = 461). The infection rates of B. globosus and B. pfeifferi are 3.5% and 0.9%, respectively. In our study, rainfall, pH, type of habitats, other freshwater snails and seasons influenced the distribution, abundance, and infection rates of human schistosomiasis intermediate host snails (p-value < 0.05). Our findings provide useful information which can be adopted in designing and implementing snail control strategies as part of schistosomiasis control in the study area.
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Affiliation(s)
- Onyekachi Esther Nwoko
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa.
| | - Tawanda Manyangadze
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
- Geosciences Department, School of Geosciences, Disaster and Development, Faculty of Science and Engineering, Bindura University of Science Education, Bag 1020, Bindura, Zimbabwe
| | - Moses John Chimbari
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa
- Department of Behavioural Science, Medical and Health Sciences, Great Zimbabwe University, P.O Box 1235, Masvingo, Zimbabwe
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Gaye PM, Doucouré S, Sow D, Sokhna C, Ranque S. Identification of Bulinus forskalii as a potential intermediate host of Schistosoma hæmatobium in Senegal. PLoS Negl Trop Dis 2023; 17:e0010584. [PMID: 37159452 DOI: 10.1371/journal.pntd.0010584] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 05/19/2023] [Accepted: 04/17/2023] [Indexed: 05/11/2023] Open
Abstract
Understanding the transmission of Schistosoma hæmatobium in the Senegal River Delta requires knowledge of the snails serving as intermediate hosts. Accurate identification of both the snails and the infecting Schistosoma species is therefore essential. Cercarial emission tests and multi-locus (COX1 and ITS) genetic analysis were performed on Bulinus forskalii snails to confirm their susceptibility to S. hæmatobium infection. A total of 55 Bulinus forskalii, adequately identified by MALDI-TOF mass spectrometry, were assessed. Cercarial shedding and RT-PCR assays detected 13 (23.6%) and 17 (31.0%), respectively, Bulinus forskalii snails parasitized by S. hæmatobium complex fluke. Nucleotide sequence analysis identified S. hæmatobium in 6 (11.0%) using COX1 and 3 (5.5%) using ITS2, and S. bovis in 3 (5.5%) using COX1 and 3 (5.5%) using ITS2. This result is the first report of infection of Bulinus forskalii by S. hæmatobium complex parasites in Senegal using innovative and more accurate identification methods to discriminate this snail and characterize its infection by S. hæmatobium.
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Affiliation(s)
- Papa Mouhamadou Gaye
- Aix-Marseille Université, IRD, AP-HM, SSA, VITROME, Marseille, France
- VITROME, Campus International IRD-UCAD de l'IRD, Dakar, Senegal
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection de Marseille, Marseille, France
- Département Biologie Animale, Faculté des Sciences et Technique, UCAD de Dakar, Dakar, Senegal
| | | | - Doudou Sow
- Department of Parasitology-Mycology, UFR Sciences de la Santé, Université Gaston Berger, Saint-Louis, Senegal
| | - Cheikh Sokhna
- VITROME, Campus International IRD-UCAD de l'IRD, Dakar, Senegal
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection de Marseille, Marseille, France
| | - Stéphane Ranque
- VITROME, Campus International IRD-UCAD de l'IRD, Dakar, Senegal
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection de Marseille, Marseille, France
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Nwoko OE, Manyangadze T, Chimbari MJ. Spatial distribution, abundance, and infection rates of human schistosome-transmitting snails and related physicochemical parameters in KwaZulu-Natal (KZN) province, South Africa. Heliyon 2022; 9:e12463. [PMID: 36793949 PMCID: PMC9922783 DOI: 10.1016/j.heliyon.2022.e12463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 10/08/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
This study investigated the spatial distribution, abundance, and infection rates of human schistosome-transmitting snails and related physicochemical parameters and environmental factors in 11 districts in KwaZulu-Natal (KZN) province, South Africa, from December 2020-February 2021. Snail sampling was carried out in 128 sites by two people for 15 min using scooping and handpicking methods. Geographical information system (GIS) was used to map surveyed sites. In situ measurements of physicochemical parameters were recorded, while remote sensing was used to obtain measurements for climatic factors required to achieve the study's objective. Cercarial shedding and snail-crushing methods were used to detect snail infections. Kruskal-Wallis test was used to test the differences in snail abundance among snail species, districts, and habitat types. A negative binomial generalized linear mixed model was used to identify the physicochemical parameters and environmental factors influencing the abundance of snail species. A total of 734 human schistosome-transmitting snails were collected. Bu. globosus were significantly more abundant (n = 488) and widely distributed (found in 27 sites) compared to B. pfeifferi (n = 246) found in 8 sites. Bu. globosus and B. pfeifferi had infection rates of 3.89% and 2.44%, respectively. Dissolved oxygen and normalized difference vegetation index showed a statistically positive relationship, while normalized difference wetness index showed a statistically negative relationship with the abundance of Bu. globosus. However, there was no statistically significant relationship between B. pfeifferi abundance, physicochemical parameters, and climatic factors. Our study described the current distribution, abundance, and infection status of human schistosome-transmitting snails in KZN province, which will contribute to informing control measure policies for schistosomiasis.
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Affiliation(s)
- Onyekachi Esther Nwoko
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa,Corresponding author.
| | - Tawanda Manyangadze
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa,Geography Department, Faculty of Science and Engineering, Bindura University of Science Education, Bag 1020, Bindura, Zimbabwe
| | - Moses John Chimbari
- Discipline of Public Health Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, 4000, South Africa,Department of Behavioural Science, Medical and Health Sciences, Great Zimbabwe University, P.O Box 1235, Masvingo, Zimbabwe
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El-Khayat HMM, Mossalem HS, El-Hommossany K, Sayed SSM, Mohammed WA, Zayed KM, Saied M, Habib MR. Assessment of schistosomiasis transmission in the River Nile at Greater Cairo using malacological surveys and cercariometry. J Parasit Dis 2022; 46:1090-1102. [PMID: 36457778 PMCID: PMC9606168 DOI: 10.1007/s12639-022-01529-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 08/26/2022] [Indexed: 11/28/2022] Open
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.
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Affiliation(s)
- Hanaa M. M. El-Khayat
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Hanan S. Mossalem
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Karem El-Hommossany
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Sara S. M. Sayed
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Wafaa A. Mohammed
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Khaled M. Zayed
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Mohamed Saied
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
| | - Mohamed R. Habib
- Environmental Research and Medical Malacology Division, Theodor Bilharz Research Institute, Giza, 12411 Egypt
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