932
Views & Citations10
Likes & Shares
Distribution
of freshwater snails were investigated in the three communities bordering
Owala/Erinle Reservoir in Olorunda and Odo-Otin local government areas of Osun
State, Nigeria using GIS between May 2008-April 2009 for 12 months. A total of
five aquatic snail species namely Bulinus
globosus, Biomphalaria pfeifferi,
Lymnaea natalensis, Potadoma freethi and Soapitia dageti were found in the reservoir. Geographical
coordinates of the villages and sampling sites were obtained using Global
Positioning System (GPS). Each of the snail species was found in all sites
investigated although Bulinus globosus
was more abundant sites of intense human contact activities. Generally the
number of B. pffeifferi, S. dageti and B. globosus showed a unimodal seasonal trend while the number of P. freethi and L. natalensis followed no discernible seasonal patterns. Factors
identified as affecting total and seasonal distribution of snail include
rainfall, ambient temperature, relative humidity and aquatic macrophyte in the
reservoir.
Keywords: Schistosomiasis, Bulinus globosus, Biomphalaria pfeifferi, Lymnaea
natalensis, Potadoma freethi, Soapitia dageti
INTRODUCTION
Schistosomiasis is a chronic and debilitating
disease of tropical communities where people make unprotected contact with
cercariae infected water bodies [1,2]. The control requires an integrated
intervention targets at the various points in the life cycle of the parasite.
Snail intermediate host is one of the focal point of the target control, which
is aimed at reducing the problem of schistosomiasis transmission in any area.
Therefore a good understanding of snail ecology is required to achieve a
successful control of the snail intermediate host thus enhancing an effective
and rapid reduction in transmission of schistosomiasis.
Snail control is very important approach for
reducing the problem of schistosomiasis in endemic areas. It has therefore been
used to achieve considerable reduction in schistosomiasis transmission in many
communities [1,3]. Snail control involved efforts directed at the number of
snails. It is generally, effective and rapid means of reducing transmission,
because the likelihood of infection depends on the number of infected snails in
a site. Snail control can be achieved through environmental, chemical and
biological control [4].
MATERIALS AND
METHODS
RESULTS
A total of 5503 snails comprising 492 (8.9%) Biomphalaria pffeifferi,
Snail
sampling
DISCUSSION
The study reveals a general
trend in the pattern of temporal variation of freshwater snails which is common
to all the species. There is a gradual decrease in number of B. pfeifferi in January but increase
begins from the month of May. This period (January) represents the peak of dry
season in the south-western part of Nigeria where L. natalensis do not follow a particular pattern. Generally, there
is an increase in the member of snail as the rain increases and visa-vice
[1,5].
The most
important determinants of the population dynamics of snails are temperature and
rainfall [6]. The optimal temperature for snail
development and survival is around 25°C. Above 30°C snail mortality increases,
and thermal death occurs at 40°C. However, snails are less sensitive to low
temperatures than schistosome parasites in snails. The seasonal variation of
snail species observed for most species in this study agreed with the trends
reported in streams and ponds in Ibadan, Western Nigeria [4] and in Opan
Reservoir [6]. Generally, the trends in density variation of B. pfeifferi and Soapitia dageti were bimodal and conformed with the classical work
of Ofoezie [4].
The
variation in the population of these species in Owalla/Erinle was seasonal,
increasing from the onset of rainy season to its peak during the dry season.
These observations were similar to other studies reported from different parts
of West Africa. It is noteworthy that B.
globosus is the only intermediate host for S. hematobium infection and its density was focal and seasonal.
This study also confirmed the snail macrophyte association as reported in the
South West of Nigeria in Oyan Reservoir, Impatiens
irvigii and Paspalum obiculare
were associated significantly with B.
globosus, B. pfeifferi was not
found in the lake) [7-9]. In Owala/Erinle reservoir the strongest associations
were recorded between Paspalum conjugatum
and between B. pfeifferi and Paspalalum orbiculare. It should be
noted that the importance and association of snails with aquatic macrophyte may
vary from region or between water bodies and region. This study has provided
useful information with regards to snail intermediate host distribution and
other associated factors. Further investigations are required in snail ecology
because not all the factors affecting snail intermediate host have been
exhausted. It has also provided useful information upon which further
investigation and sustainable intervention control target could be based in
communities. The trend has serious implications for human health and overall
outcome of control programmes in the study communities and the region at large
[10-12].
CONCLUSION
This study identified the presence of five
aquatic snail species namely Bulinus
globosus, Biomphalaria pfeifferi,
Lymnaea natalensis, Potadoma freethi and Soapitia dageti were found in the reservoir. Factors identified as
affecting total and seasonal distribution of snail include rainfall, ambient
temperature, relative humidity and aquatic macrophyte in the reservoir. The prevalence of these snails is a
function S. hematobium infections in
the study communities; which has become a disease of public health importance
since it was first discovered in the area by Adewumi et al. [13]. The present work has
provided complementary baseline information, which will be useful for planning
control measures against schistosomiasis.
This study has provided clear evidence of the
link between: (i) Presence
types, number and the pattern of distribution of snail intermediate host and
other snails; (ii) Identified aquatic maprophytes at six HWC sites and their
association with snails.
RECOMMENDATIONS
1. There
is the need for continuous mapping using GIS/RS, health education, and
provision of alternative sources of water, mass drug administration and
freshwater snail control in the study communities.
2. There
is need to put the necessary mitigating measures in place by carrying out an
Environmental Impact Assessment before and after a dam is constructed for
sustainable LU/LC pattern, less pollution towards sustainable growth.
1. Oladejo, Ofoezie (2006) Unabated
schistosomiasis in Erinle river dam, Osun State, Nigeria: Evidence of neglect
of environmental effects of development. J Trop Med Int Health 11:
843-850.
2. Oladejo SO (2004) Transmission of
schistosomiasis in Erinle/Owala reservoir in Olorunda local Government area,
Osun State, Nigeria. M.Sc. Thesis. Institute of Ecology and Environmental
Studies, Obafemi Awolowo University of Ife, Nigeria.
3. Ofoezie IE (1995) A study of
urinary schistosomiasis in resettlement communities, bordering Oyan river dam,
Ogun State, Nigeria Ph.D. Thesis Obafemi Awolowo University, Ile-Ife, Nigeria.
4. Ofoezie IE, Asaolu SO, Christensen
NO, Madson H (1997) Patterns of infection this Schistosoma hematobium in lake side resettlement communities at
Oyan reservoir in Ogun State, south-western Nigeria. Annu Trop Med Parasitol 91:
137-219.
5. Ofoezie IE (2002) Urban detection
from remotely sensed data of Ikeja area, Lagos, Nigeria. M.Sc. thesis.
Institute of Ecology and Environmental Studies, Obafemi Awolowo University of
Ife, Nigeria. Microsoft® Encarta®.
6. Owojori OJ (2003) Econlogy of
Schistosoma intermediate host snails in Opa reservoir and research farm ponds
at Oba Feme, Awolowo University, Ile-Ife.
7. Ashaolu SO, Ofoezie IE (1990) A
simple method for concentrating eggs of Shistosoma
hematobium in the urine. Nig J Parasitol 9-11: 47-50.
8. Mafiana CF, Omotayo AB (1998)
Urinary schistosomiasis and evaluation of microscopic egg count and chemical
reagent strip in children in southwest Nigeria. Helminthological 35: 31-35.
9. Tayo MA, Jew S, Bury JM (1997)
Malumfashi edemic diseases research project IV: Changes in snail population
following the construction of a snail dam. Annual of Tropical Medicine and
parasitological, 72: 483-487.
10. Oladejo SO (2005) Fundamentals of
Ecology. Katolad Publishers: Osogbo.
11. Oladejo SO (2009) Fundamentals of
Biology of Parasites. Katolad Publisher: Osogbo.
12. Oladejo SO (2007) Ecological
effect of human activities in the environment: Way forward. Workshop on
Environmental Science Technology: African Regional Centre for Space and
Techology, O.A.U. Ile-Ife, Nigeria.
13. Adewumi (1993) Schistosomiasis and
intestinal parasites in the villages in southwest Nigeria: An indication for
expanded programme in Nigeria. Trop Parasitol 44: 174-180.
-
Table 1 -
Table 2
-
Table 3
QUICK LINKS
- SUBMIT MANUSCRIPT
- RECOMMEND THE JOURNAL
-
SUBSCRIBE FOR ALERTS
RELATED JOURNALS
- Journal of Womens Health and Safety Research (ISSN:2577-1388)
- Journal of Veterinary and Marine Sciences (ISSN: 2689-7830)
- Food and Nutrition-Current Research (ISSN:2638-1095)
- Journal of Genetics and Cell Biology (ISSN:2639-3360)
- Advances in Nanomedicine and Nanotechnology Research (ISSN: 2688-5476)
- Journal of Microbiology and Microbial Infections (ISSN: 2689-7660)
- Proteomics and Bioinformatics (ISSN:2641-7561)
