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American Journal of  
Life Science and Innovation (AJLSI)

Transmission of  Urogenital Schistosomiasis in Owena Reservoir Area, Ondo State
Nigeria: Nexus Between Different Pathogenic Host Factors

Bayo Joshua Peletu1, Ifeanyi Emmanuel Ofoezie2, Aloysius Obinna Ikwuka3*

Volume 2 Issue 2, Year 2023
ISSN: 2833-1397 (Online)

DOI: https://doi.org/10.54536/ajlsi.v2i2.1788
https://journals.e-palli.com/home/index.php/ajlsi

Article Information ABSTRACT

Received: June 20, 2023
Accepted: July 08, 2023
Published: July 24, 2023

A total of  25,482 snails, comprising 4,258 (16.7%) Bulinusglobosus; 213 (0.8%) 
Bulinustruncatus; 4,040 (15.9%) Bulinusforskalii; 4,770 (18.7%) Biomphalariapfeifferi; 
6,024 (23.6%) Melanoidestuberculata; 1,730 (6.8%) Potadomafreethi; and 4,447 (17.5%) 
Pilaovata were collected over a period of  24 months during monthly site visits to Owena 
Reservoir Area which comprises of  three communities namely Owena, Baiken and Kajola 
in Ondo East Local Government Area, Ondo State, Nigeria. Abundance of  each of  the 
snail species varied significantly (p<0.05), spatially, seasonally and annually throughout the 
period under study. The established intermediate snail host species were Bulinusglobosus and 
Bulinustruncatus for Schistosomahematobium transmission. The overall infection rate among 
Bulinusglobosus was 3.2% as 136 snails were found to shed cercariae out of  4,258 collected 
and examined for trematode infection. This occured at site 4 located in Kajola community. 
None of  the Bulinustruncatus species was found to shed cercariae.

Keywords
Urogenital Schistosomiasis, 
Bulinus Globosus, Bulinus 
Truncatus, Schistosoma 
Hematobium, Owena Reservoir 
Area, Pathogenic Host Factors, 
Schistosomiasis, Public Health, 
Mollusc

INTRODUCTION
Schistosomiasis is a disease caused by parasitic trematode 
worms of  the genus Schistosoma (Weinland, 1858). Out 
of  these trematode worms infecting humans, only 
S.hematobium and S.mansoni are of  great medical importance. 
While S.hematobium causes urogenital schistosomiasis, the 
other species - S.mansoni causes intestinal schistosomiasis. 
The parasite S.hematobium is found in the venous plexus 
draining the urinary bladder of  humans (Babatunde, 
2013; WHO, 2014). Infections result from the parasites 
depositing terminal, spined eggs which clog the venous 
plexuses, thus preventing blood flow which leads to 
the bursting of  the veins, allowing blood and eggs to 
enter the urinary bladder resulting in the characteristic 
symptom of  blood in the urine (hematuria) (Ekpo, 
2010; Peletu, 2016; Peletu, 2023b; WHO, 2014; WHO, 
2015). In Nigeria, it has been reported that urogenital 
schistosomiasis is endemic in 23 out of  the 36 states of  
Nigeria. Ondo State is one of  the states where urogenital 
schistosomiasis occurs (Peletu, 2020; Peletu, 2023a; 
Peletu, 2023b; Peletu, 2023c). However, epidemiological 
information of  the disease in Ondo State, especially in 
the three communities bordering Owena Reservoir/
Dam, is still very scanty. Information on the transmission 
of  urogenital schistosomiasis and human water contact 
patterns in Ondo State is scanty despite the widespread 
distribution of  the disease in some of  its neighboring 
states (Peletu, 2020).
Water contact activities exposed the communities to 
urogenital schistosomiasis infection. It is recommended 
that health education on the transmission of  urogenital 

schistosomiasis should be focused on mass sensitization, 
to emphasize the role commonly played by water contact 
activities of  snail hosts (Peletu, 2023c). Contamination 
habits such as urination and defecation in the water bodies 
should be discouraged. People should avoid wading into 
infected water bodies indiscriminately (Peletu, 2023c).
Urogenital schistosomiasis is highly endemic in three 
communities (Owena, Baiken and Kajola) of  Ondo State, 
Nigeria (Peletu, 2023a). There is a need for sustainable 
controls targeted towards behavioral modifications by 
mass sensitization and provision of  pipe-borne water 
facilities and modern toilet systems with a view to 
discouraging people from having contact with cercacriae-
infected water bodies (Peletu, 2023a).
Urogenital schistosomiasis and its concomitant hematuria 
are prevalent in Owena, Baiken and Kajola communities 
of  Ondo East Local Government Area, Ondo State, 
Nigeria. In all three communities of  Owena, Baiken and 
Kajola, urogenital schistosomiasis would be most difficult 
to treat and/or eradicate in Baiken community (Peletu, 
2023b). Efforts by stakeholders should be geared towards 
implementing full control strategies such as the provision 
of  pipe-borne water, modern toilet facilities, and regular 
chemotherapy controls to the school-age children and 
adults of  the age group 21–30 years (Peletu, 2023b).
S.hematobium is transmitted by the intermediate host 
belonging to the genus Bulinus (Akinwale, 2010; Fradsen, 
1984; Peletu, 2010). In the last decade, there has been 
considerable advancement in the knowledge of  the 
basic relationship between Bulinus and S.hematobium 
(WHO, 2015). 

1 Department of  Allied Health & Biological Sciences, College of  Health Sciences (CHS), Legacy University, Banjul, Gambia
2 Institute of  Ecology & Environmental Studies, Obafemi Awolowo University, Ile-Ife, Nigeria
3 Department of  Clinical Sciences, College of  Health Sciences (CHS), Legacy University, Banjul, Gambia
* Corresponding author’s e-mail: aloysiussweet@yahoo.com



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Am. J. Life Sci. Innov. 2(2) 12-16, 2023

The resolutions of  snail populations in a given aquatic 
habitat are influenced by abiotic factors such as temperature, 
ions e.g., sodium, calcium, biochemical oxygen demand 
(BOD), dissolved oxygen (DO), sunlight, alkalinity, water 
current velocity, rainfall, and biotic factors such as predator-
prey interactions/relationships, food availability, habitat 
competitions, hydromicrophytes coverage (Ofoezie, 1995; 
Ofoezie, 2002; Peletu, 2010; Theron, 1986; Udonsi, 1990). 
The twenty-four month study (August 2013 – July 2015) 
was carried out with a view to determining the nexus 
between the different pathogenic host factors, the seasonal 
and spatial distribution of  infection patterns (cercariae 
shedding) of  identified local intermediate snail host 
species in the transmission of  urogenital schistosomiasis 
in Owena Reservoir Area, Ondo East Local Government 
Area, Ondo State, Nigeria. This is especially necessary 
when planning sustainable control programs of  the disease 
in the study area.

MATERIALS AND METHODS
Study Area
The twenty-four month study (August 2013 – July 2015) 
was carried out in Owena Reservoir and its adjoining three 
randomly selected communities namely Owena, Baiken 
and Kajola, which are rural to semi-urban settlements 
located in Ondo East Local Government Area, Ondo 
State, Nigeria. Owena Reservoir lies between latitudes 
7000’ – 7030’N and longitudes 5000’ - 5030’E (see Fig. 1). 
The residents are generally peasant farmers, petty traders, 
local teachers, oil mill workers, fishermen, and auxiliary 
health officers. Owena Reservoir has a catchment area 
of  approximately 900km2. Its major tributaries are rivers 
Owena and Anu. According to the National Population 
Commission (2006), the population of  the communities 
is approximately 9,000.

Figure 1: Map of  Owena showing Owena Reservoir, Owena Dam, Owena River, and the eight sampling sites of  
Owena, Baiken, and Kajola communities
Source: Igboloro and Associates (Planners, Architects, and Engineers), 3 Ayodele Awodeyi Street, Ketu, Lagos State, Nigeria (2012)



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Selection of  Sampling Sites
The sampling sites were selected based on the fact that 
they are potential human water contact sites where the 
frequency of  visitations by the inhabitants and proximity 
to their residences were considered paramount parameters 
for snail-breeding sites.

Snail Sampling
The eight sites selected were sampled once every month for 
twenty-four-months (August 2013 – July 2015). Sampling 
involved 30 passes of  kitchen scoops and a manual search 
for 30 person-minutes (Asaolu, 1990; Peletu, 2010; WHO, 
2014). All the snails collected were placed in pre-labeled 
plastic containers with decaying leaves, and transported 
to the Malacology Laboratory of  Obafemi Awolowo 
University, Ile-Ife, Nigeria. Water used to shed cercariae 
was collected from each of  the eight sites. Within 24 hours 
upon arrival at the Malacology Laboratory, the snails 
were identified to species level, counted, and recorded 
as number of  snails per site, per date. The snails were 
identified using standard identification keys. The snails 
were then grouped into <3.0mm, 3.0mm-5.9mm, and 
6.0mm-9.0+mm size classes, using a fine vernier caliper. 

Examination of  Snails for Schistosoma infection
The snails identified were examined for Schistosoma 
infection using the crushing method (Asaolu, 2003). 
Each of  the snails was placed on a slide and was covered 
with another slide with minor pressure applied on the 
topmost slide to gently crush the snail. Some drops of  

dechlorinated water were added to the longer pieces of  
shell removed, using small forceps. The slide was then 
observed under a light microscope for the presence or 
absence of  cercariae. The cercariae were identified to 
the genus level according to Frandsen and Christensen 
(Fradsen, 1984). However, only snails shedding Schistosoma 
cercariae were recorded as infected. Other data about 
size, species, date of  collection, and site of  selection of  
infected snails were recorded.

RESULTS AND DISCUSSION
Table 1 shows that for the period under study (August 2013 – 
July 2015), a total of  25,482 snails, comprising 4,258 (16.7%) 
Bulinusglobosus; 213 (0.8%) Bulinustruncatus; 4,040 (15.9%) 
Bulinusforskalii; 4,770 (18.7%) Biomphalariapfeifferi; 6,024 
(23.6%) Melanoidestuberculata; 1,730 (6.8%) Potadomafreethi; 
and 4,447 (17.5%) Pilaovata were collected during monthly 
site visits to Owena Reservoir Area which comprises of  
three sampled communities namely Owena, Baiken and 
Kajola in Ondo East Local Government Area, Ondo State, 
Nigeria. Thus, Bulinusglobosus and Bulinustruncatus were the 
established intermediate host (see Table 1). 
Out of  the two intermediate snail host species identified, 
Bulinusglobosus was more abundant - 4,258 (16.7%) than 
Bulinustruncatus 213 (0.8%). The overall infection rate of  
Bulinusglobosus was 3.2% as 136 snails were infected out of  
the 4,258 collected (see Table 2). This was found in Site 4 
located in Kajola community. Only Bulinusglobosus greater 
than 3.0mm were found to shed cercariae (infected).

Table 1: Total number of  each of  the seven snail species collected within twenty-four months during monthly site visits
Sites Bulinus 

globosus
Bulinus 
truncatus

Bulinus 
forskalii

Biomphalaria 
pfeifferi

Melanoides 
tuberculata

Potadoma 
freethi

Pila 
ovata

Total

Owena
Site 1 554 62 396 599 771 557 433 3,372
Site 2 567 46 425 485 623 784 713 3,643
Site 3 555 17 552 630 676 65 983 3,478
Kajola
Site 4 607 11 645 739 955 101 953 4,011
Site 5 688 16 570 534 890 76 656 3,430
Baiken
Site 6 511 16 544 558 670 92 345 2,736
Site 7 461 17 487 544 664 15 109 2,297
Embankment/Dam - Owena
Site 8 315 28 421 681 775 40 255 2,515
Total 4,258 213 4,040 4,770 6,024 1,730 4,447 25,482

Table 2: The relative abundance and rates of  Schistosoma infection (cercariae shedding pattern of  small (3.0mm-
5.9mm) and large (6.0mm-9.0+mm) Bulinusglobosus collected during monthly site visits to Owena Reservoir Area
Sites Small snails (3.0mm-5.9mm) Large snails (6.0mm-9.0+mm) Total 

Total 
Collected

Total 
Infected

% 
Infection

Total 
Collected

Total 
Infected

% 
Infection

Total 
Collected

Total 
Infected

% 
Infection

Owena
Site 1 113 0 0 408 11 2.7 521 11 2.1



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CONCLUSION
Bulinusglobosus and Bulinustruncatus are the only identified 
intermediate hosts of  Schistosomahematobium in Owena 
Reservoir Area. Bulinusglobosus showed predominance 
compared to the other intermediate snail host species at 
Owena Reservoir Area. Therefore, intervention strategies 
for sustainable control of  urogenital schistosomiasis in 
Owena Reservoir Area should focus on the two snail host 
species. The use of  molluscicides should be encouraged.

Acknowledgments
Special thanks to the entire staff  of  Malacology 
Laboratory of  Obafemi Awolowo University, Ile-Ife, 
Nigeria for their assistance in carrying out this research.

Conflict of  Interest
All the authors hereby declare that they do not have any 
possible conflicts of  interest.

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Site 2 163 0 0 413 15 3.6 576 15 2.6
Site 3 154 0 0 378 12 3.2 532 12 2.3
Kajola
Site 4 158 6 3.8 466 47 10.1 624 53 8.5
Site 5 176 0 0 504 6 1.2 680 6 0.9
Baiken
Site 6 131 0 0 399 13 3.3 530 13 2.5
Site 7 121 0 0 357 24 6.7 478 24 5.0
Embankment/Dam - Owena
Site 8 0 0 237 2 0.8 317 2 0.6
Total 1,096 6 0.6 3,162 130 4.1 4,258 136 3.2



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