ABSTRACT
The study aimed at surveying the prevalence of Schistosoma haematobium, freshwater snail vector of S. haematobium, physio-chemical properties of freshwater and factors influencing the transmission and spread of S. haematobium in Afikpo North Local Government Area, Ebonyi State from February 2016 to January 2017. The subjects’ urine were examined for S. haematobium through centrifugation and sedimentation. Of 504 persons randomly screened for S. haematobium, 20 (3.97%) were infected. Males were more infected 12 (4.8%) than the females 8 (3.15%). Sex was not statistically associated with prevalence of S. haematobium (X2 = .901, df= 1, P> 0.05). The average intensity/10ml count among those infected was 21eggs/10ml of urine. The intensity of infection (8.1) was highest in age group 14-16 yrs. There was no significant relationship that exist between the age and the prevalence of S. haematobium (X2 = 1.506, df= 4, P> 0.05). There exist a significant relationship between sources of water and the prevalence of S. haematobium (P< 0.05). There was no significant relationship between occupation of the parents and the prevalence of S. haematobium (P> 0.05). Prevalence of S. haematobium was high in February 3 (7.8%) and low in October 1(1.85%). There was no significant relationship between the season and the prevalence of S. haematobium (P> 0.05). This study revealed freshwater snails with particular reference to Bulinus species. A survey of snail abundance in relation to location/sampling site showed that Ohia stream had the highest abundance of snail with a total of 44 snails while Iyi Akpoha had the least abundance of snails with 27 snails. Each of the Bulinus species was placed in a glass beaker filled with 100ml of water, and then exposed to sunlight for 30mins which facilitated shedding of cercariae and examined. A survey of the infection rate of Bulinus species collected in different sampling sites showed that out of 102 Bulinus species collected 11 (10.8%) were infected. Ohia sample location had the highest infection rate of Bulinus species 5 (15.6%) and the least was in Iyi Akpoha 0(0%). There was no significant relationship between sampling sites and the rate of snail infection (P> 0.05). Bulinus species infection rate in relation to month/season was high in December 1 (25%). A survey of snail abundance in relation to physico-chemical properties which include temperature, pH, dissolved oxygen, alkalinity and conductivity was conducted. There was no significant relationship between physico-chemical properties of water and snails abundance as well as infected snail (P>0.05). The most densely occurring macrophyte was Carex austro-africana. The result revealed that increase in aquatic macrophytes yielded concomitant increase in the snail abundance (P< 0.05). Based on the findings of this study, it is evident that prevalence of S. haematobium infections in the area is low. Therefore, effort should be intensified to maintain levels below threshold and eradicate urinary schistosomiasis in Afikpo North L.G.A. Ebonyi State.
TABLE OF CONTENTS
Cover
Page
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table
of Contents vii
List
of Tables xi
List
of Figures xiii
List
of Plates xiv
Abstract xv
CHAPTER 1
1
INTRODUCTION
1
1.0
Statement of Problem 4
1.1
Aim and Objectives
4
1.2
Significance of Study
5
1.3
Justification
6
CHAPTER 2
7
LITERATURE REVIEW 7
2.1
Brief History of Schistosomiasis
7
2.2
Global Distribution of Schistosomiasis
10
2.3
Schistosomiasis in Nigeria
13
2.4
Transmission of Schistosomiasis
15
2.5
Reservoir Host of Schistosomes 18
2.6
Pathogenesis of Schistosomiasis
19
2.7
Public Health Significance of Schistosomiasis 23
2.8
Diagnosis of Schistosomiasis
23
2.9
Treatment and Control of Schistosomiasis 24
2.10
Ecology and Distribution of Freshwater Gastropods
of
Medical Importance 26
2.10.1
Bulinus species
27
2.10.2
Biomphalaria species
29
2.10.3
Oncomelania 30
2.10.4
Tricula
31
2.11
Review of Distribution of Snail Intermediate Host of Schistosomes. 31
2.12
Physico-chemical Properties of Freshwater 32
2.13 Aquatic Macrophytes
36
2.14
Food and Feeding Habits of Snail
36
2.15
Control of Intermediate Host (Snails)
37
CHAPTER 3
MATERIAL AND METHODS
42
3.1
Study Area
42
3.2
Ethical Approval
45
3.3
Data Collection
45
3.4
Sampling Techniques of Urine
45
3.5
Urine Sample Size Determination
46
3.6
Examination of Urine Sample for S.
haematobium
46
3.7
Malacological Sampling
47
3.8
Collection and Identification of Aquatic Macrophtes 51
3.9
Physico- Chemical Parameters of the Water Bodies 52
3.9.1 Examination of snails
52
3.9.2 Measurement of chemical parameters of
water
52
3.10.
Statistical Analysis
56
CHAPTER 4
RESULTS AND DISCUSSION
57
4.1 Parasitological Survey
57
4.1.1. Community school related prevalence of
urinary schistosomiasis. 57
4.1.2. Age related prevalence of urinary
schistosomiasis
63
4.1.3. Gender related infection rate of urinary
schistosomiasis 65
4.1.4. Sources of water supply related infection
rate
68
4.1.5. Prevalence of urinary schistosomiasis in
relation to
occupation of parents
71
4.1.6. Seasonal/Monthly prevalence of urinary
schistosomiasis 74
4.2. Malacological Survey
80
4.2.1. Snail abundance in relation to month 80
4.2.2. Snail abundance in relation to location and
cercariae shedding of Bulinus
species
83
4.2.3. Snail abundance in relation to
physico-chemical
properties of
water 91
4.2.4. Bulinus
species shedding of cercariae in relation to
physico-chemical properties of water 107
4.2.5. Snail abundance in relation to aquatic macrophytes 110
CHAPTER 5
CONCLUSION AND RECOMMENDATIONS 120
5.0. Conclusion
120
5.1. Recommendations
121
REFERENCES 123
APPENDIX 141
LIST OF TABLES
4.1: Prevalence rate of S.
haematobium infection by Community
School in Afikpo North L.G.A. Ebonyi State. 59
4.2: Age specific prevalence and intensity of
S. haematobium
infection. 64
4.3: Gender- related prevalence of S.
haematobium. 67
4.4. Prevalence of S. haematobium
infection
according to sources of water supply.
70
4.5: Urinary Schistosomiasis infection
relation to
occupation of parents.
73
4.6: Urine samples collected seasonally in
each
School/sampling location. 76
4.7: Prevalence of Urinary Schistosomiasis in
wet and dry season in Afikpo North L.G.A. Ebonyi State. 79
4.8: Monthly/ Seasonal
collection of snails in
different sampling sites in relation to cercariae
shedding in Afikpo North L.G.A. Ebonyi State. 86
4.9: Infection rate of Bulinus species in different sampling
sites. 87
4.10:
Monthly/Seasonal collection of snails in relation to
Bulinus species infection in Afikpo North L.G.A. 88
4.11: pH values of water samples collected
monthly/seasonally in each sampling location 92
4.12. Temperature of water samples collected
monthly/seasonally in each sampling location 93
4.13. Dissolved oxygen mg/l of water samples
collected
monthly/seasonally in each
sampling location 95
4.14. Alkalinity values of water samples
collected
monthly/seasonally in each sampling location 96
4.15. Conductivity values of water samples
collected
monthly/seasonally in each sampling location 98
4.16. Relationship between snail abundance,
snail that shed cercariae and average water quality values. 101
4.17. Relationship between Bulinus species
that shed cercariae and average water quality value. 109
4.18. Specie abundance of aquatic macrophytes
in
relation to snail abundance
115
LIST OF FIGURES
1: Map showing global distribution of
schistosomiasis
12
2: Life cycle of Schistosoma species.
17
3: Map of Afikpo North L.G.A. Ebonyi
State. 44
LIST OF
PLATES
1: Drying Ugwagwo pond in Ezeke Eziukwu
Amasiri 48
2: Uke Ezego stream in Ibii
48
3: Ohia stream in Amasiri showing aquatic
vegetation 49
4: Iyi Ogologo in Akpoha showing aquatic
vegetations 49
5: Iyi Akpoha in Amogu Akpoha
50
6: Egg
of Schistosoma haematobium
58
7: Schistosoma haematobium egg in
urine 58
8: Snails of Bulinus species collected in the study area 82
9: Furcocercous cercariae from the infected
snail 85
10: Carex austro-africana
112
11: Aspilia africana 112
12: Nymphae
lotus
113
13: Co-existence of Carex austro-africana,
Aspilia africana, Eleocharis acutangular,
Typha latifolia and Mimosa Pudica in Iyi Ogologo Akpoha. 113
CHAPTER 1
INTRODUCTION
Freshwater molluscs are those members of phylum Mollusca which
dwell in freshwater habitats both lentic (stagnant water) and lotic water
(flowing water). Gastropod is a class of molluscs in freshwater that harbours
and transmits infective stages of some animal parasites to human. The role of freshwater
molluscs in public and vetrinary health cannot be overlooked and needs to be precisely
studied (Supian and Ikhwanuddin, 2002; El-Khayat et al, 2011). Various species of the class gastropoda have been
known to harbor trematode organisms. The families of Pildae and Thiaridae were
recorded to harbor larval trematodes (Subba-Rao, 1993; Mostafa, 2009). There
are several ecological influences that disturb snails and other transitional
hosts of parasites which affect their distributions. These factors are
temperature, rate of water flow, turbidity, transparency, distribution of
suspended solids, ion concentration, dissolved gases in water, availability of
food, and predator-prey interactions (Ofoezie, 1999; Garg et al., 2009). Besides, aquatic macrophytes play vital roles in the
distribution of snails in different parts of Africa (Ofoezie 1999). However,
the significance of various environmental factors differ from one environmental
area to the other and even from one aquatic habitat to the other. This
signifies that extensive study of these ecological communities’ needs to be
carried out to detect essential influences in each community or water bodies (Ofoezie,
1999; Hussien et al., 2011). Many
researches relating to ecology and changing aspects in population of freshwater
snails which show significant roles in transferring infections to man and his
livestock have been carried out by Abd El-Malek (1958), Dazo et al.1966; Barbosa and
Barbosa1994); Utzinger et al. (1997); Kloos et al. (2001); Karimi
et al., (2004); Cañete et al. (2004) Kazibwe et al. 2006 and Mostafa, 2009). These
ecological researches have led to the general opinion that the advance of a
real approach of collective control needs the study of ecological dissemination
of the transitional hosts and its relation to ecological influences. Ecological
distribution of these organisms rest on the physical topography of a certain
region. Landscape, soil structure, hydrography and climatic conditions have influence
on freshwater snail distribution (El-Khayat et al., 2011).
Usually, changes in climate affect the humans or animals and the
snail populations (Chandiwana et al., 1987; Garg et al., 2009). Despite this known seasonality of transmission of
snail-borne infections due to climate, there appears to be a circadian rhythm
of discharge of parasite eggs and peak abundance of infective larvae in the
habitats at given times (Owojori et al., 2006).
The biological advantage of these rhythms is that they are means
of facilitating transmission. The other
implication is that they show that the snails are always existing for the
miracidia hatching out of trematode eggs within defined periods that support
abundance of snails. It thus becomes imperative that for any identified snail
habitat, a full understanding of the snail population dynamics, the bionomics
and other biotic interactions are important in the overall assessment of the
habitat with respect to its role in snail-borne disease transmission.
Macro dissemination of freshwater snails has become the subject of
many surveys. In most habitats, it has been discovered that these snails are
limited by temperature, rainfall and drought. For this reason, most snail species
will fail to inhabit some habitats and become abundant in other habitats. It is
therefore, very important that factors of the environment that affect the macro
dissemination of freshwater gastropods in any environment are investigated and
used to understand the biological interactions within the habitats. While serious
consideration is given to the macro distribution of snail genera and species, a
lot more attention needs to be paid to the micro distribution parameters of the
species. For example, it will be highly instructive to understand the factors
that support oviposition, egg hatching and survival of the young snails in
their preferred habitats. In his studies, Chase (2007) found that thermic
stability appeared to determine substrate selection in adult gastropods and it
would be interesting to find out if the young snails are similarly affected.
According to Chase (2007) the number of eggs and juveniles increase with the
increase in temperature during the morning (from 6.30 am), and with decrease of
temperature later in the morning (around 10.00 am). This finding suggests the
need to study the roles of temperature in the freshwater habitat. Certain
habitat factors may clearly correlate differently between eggs, juveniles and
adults. For example, in land gastropods, it has been noted that humidity of
litters and soil and season correlate mainly more for eggs than other stages
(El-Khayat et al., 2011).
1.0.STATEMENT OF
PROBLEM
Schistosomiasis is an acute and chronic
disease caused by parasitic worms. People are infected during routine
agricultural, domestic, occupational, and recreational activities, which expose
them to infested water. Schistosomiasis is a disease associated with poor
environmental sanitation and increased development of water resources to meet
the demands of man. (WHO, 2018) Schistosomiasis affects many communities in
Afikpo North L.G.A. especially farmers and those living near water causing
illness that prevent people from farming, attending to schools, performing
other activities, and at times gives rise to malignancies which are fatal
(Utzinger et al., 2015).
Schistosomiasis being a public health problem in Nigeria has not yet been controlled due to factors like infection and
re-infection which is as a result of the vector; freshwater gastropods which
facilitate transmission. The study of the ecological distribution of freshwater
gastropod vector of Schistosoma
haematobium will assist in integrating effective control approach to
eradicate urinary schistosomiasis. In order words intermediate host control is
schistosomiasis control.
1.1.
AIM AND OBJECTIVES: The
aim of this research work was to determine the true picture of urinary
schistosomiasis in the study area using school children below 16 years and to
investigate the factors that enhance the transmission of S. haematobium in
Afikpo North Local Government Area, Ebonyi State.
The
objectives of this study were as follows:
1. To
determine the prevalence of Schistosoma
haematobium among school children below 16 years in Afikpo North Local Government Area, Ebonyi
State.
2.
To determine prevalence
of water snail vector of S.
haematobium in Afikpo North
Local Government Area, Ebonyi State.
3.
To ascertain the physico-chemical
properties of the surrounding water bodies of the Afikpo North Local Government Area, Ebonyi State.
4. To
determine factors influencing the transmission and spread of S. haematobium in Afikpo North Local Government Area, Ebonyi
State.
1.2.
SIGNIFICANCE OF STUDY
Schistosomiasis, a
water-based disease is spread
through contact with
water in which
snails harboring and
shedding the infective stage
(cercariae) of the
parasite (Schistosoma) are present. Several factors such as social,
environmental and behavioral directly influence the prevalence and intensity of
schistosomiasis. It is important that these factors be identified to aid in designing
control programmes. Environmental conditions and sewage disposal are
deplorable, indiscriminate defaecation and urination are very common, the
literacy level is very low and there is inadequate safe/potable water with
consequent effects on the population. Most of the water bodies in Afikpo North
harbor the snail intermediate host, and this helps to increase the prevalence
of schistosomiasis. The study on Ecological distribution of the snails is to
ascertain the true picture of the disease in relation to presence of S. haematobium vector and prevalence in
Afikpo North L.G.A. Ebonyi State.
1.3.
JUSTIFICATION
The
most significant trematodes in Nigeria from a clinical point of view are bloodflukes, Schistosoma mansoni and Schistosoma haematobium. Investigations from researchers
have shown the intensity and prevalence of Schistosomiasis in most parts of the
country. Nigeria is estimated to have the highest number of people infected
with Neglected Tropical Diseases in Africa which is a group of parasitic and
bacterial infections that affect the world’s poorest populations. Nigeria has
the highest burden of endemicity of schistosomiasis (WHO 2015; Hotez and Aruna
2009). Some of the investigations of freshwater snails and Schistosomiasis in
Nigeria include those of Hira (1970) and Adewunmi et al (1990) for South West city and its environs, Okwuosa and
Ukoli (1980) for Lagos, Ogun and Oyo States, Ndifon (1989) for South Western
Nigeria, Nmorsi et al (2005) in Edo
State, Okafor (1990), Denis et al
(2013) in Anambra State, Nduka et al (2008),
Ivoke et al (2014) in Ebonyi State.
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