LIST OF FIGURES
Figure I: Map of Aniocha North LGA Delta State of Nigeria – 30
vi
LIST OF PLATES
Plate I: Subjects with Onchocercal Nodules – – – 38
Plate II: Subjects with Leopard skin – – – – – 39
vii
LIST OF TABLES
Table I: Results of Clinical Examination of the 450
Randomly selected subjects from four communities
in Aniocha North LGA, Delta State 2009 – – – 40
Table II: Prevalence of Onchocercal Manifestation with
Respect to Age in the Study Area – – – – 41
Table III: Prevalence of Onchocercal Manifestation with
Respect to Sex in the Study Area – – – – 42
Table IV: Prevalence of Onchocerciasis in Relation to Age
and Sex in the Study Area – – – – – 43
Table V: Prevalence of Onchocerciasis with respect to
Occupation in the Study Area – – – – 44
viii
TABLE OF CONTENT
Title page – – – – – – – – – – i
Approval Page – – – – – – – – – ii
Dedication Page – – – – – – – – – iii
Acknowledgement – – – – – – – – iv
List of Figures – – – – – – – – – v
List of Tables – – – – – – – – – vi
List of Plates – – – – – – – – – vii
Table of Contents – – – – – – – – viii
Abstract – – – – – – – – – – xi
CHAPTER ONE
1.0 Introduction – – – – – – – – 1
CHAPTER TWO
2.0 Literature Review – – – – – – – 5
2.1 Epidemiology of Onchocerciasis – – – – – 5
2.2 Distribution of Onchocerciasis – – – – – 6
2.3 Clinical Manifestations of Onchocerciasis – – – 7
2.4 Prevalence of Onchocerciasis in Nigeria – – – – 8
2.5 Factors influencing the Epidemiology of the Disease – – 11
2.5.1 Host Factors – – – – – – – – 11
ix
2.5.2 The Vector – – – – – – – – – 12
2.5.3 The Parasite – – – – – – – – 14
2.5.4 Occupation Factor – – – – – – – 14
2.5.5 Community Factor – – – – – – – 15
2.5.6 Cultural Factor – – – – – – – – 15
2.5.7 Proximity of Population to Breeding Sites – – – 15
2.6 Nature of the Disease (Clinical/Signs and Symptoms) – 16
2.7 Diagnosis – – – – – – – – – 19
2.8 Parameter for measuring Endermicity – – – – 21
2.9 Socio Economic Importance of Onchocerciasis – – 21
2.10 Control – – – – – – – – – 24
CHAPTER THREE
3.0 Materials and Methods – – – – – – – 28
3.1 Study Area – – – – – – – – – 28
3.2 Methodology – – – – – – – – 31
3.2.1 Ethnical clearance and mobilization – – – – 31
3.2.2 Subject Examination – – – – – – – 31
3.2.3 Palpation for presence of Onchocercal nodules – – 32
3.2.4 Physical Examination of skin for Onchodermatitis,
Leopard Skin, Handing groin, Scrotal Enlargement
and Clitoral Enlargement – – – – – – 33
x
3.2.5 Visual Equity or Impaired Vision Screening – – – 33
3.3 Data Analysis – – – – – – – – 33
CHAPTER 4
Results – – – – – – – – – – 35
CHAPTER FIVE
Discussion – – – – – – – – – – 45
References – – – – – – – – – 50
Appendix I – Individual Examination Form – – – – 59
Appendix II – Chi-Square Test for Significance – – – – 60
xi
ABSTRACT
A cross-sectional study was carried out in four farming
communities in Aniocha North Local Government Area of Delta State of
Nigeria, Idumuogo, Ogodor, Anioma and Ubulubu – between November
2008 and March 2009.
The study was carried out to determine the current status of
Onchocerciasis in the communities, through the study of the clinical
manifestations of the disease and socio-economic effects on the
sufferers, and to connect on the ongoing control measures with
ivermectin in the area.
A total of 450 subjects were selected for examination for clinical
manifestation of Onchocerciasis. 140 (31.1%) males, and 104 (23.1%)
females were found to be infected with one or two clinical
manifestations. Although infections were found in all age groups, it
occurred mostly in older groups. Various rates of clinical manifestation
were recorded thus: leopard skin 106 (24%), Onchocercal nodules 32
(7.1%), Onchodermatitis 51 (11.3%), itching 50 (11.1%) and impaired
vision 18 (4.0%) with Idumuogo and Ubulubu, having the highest
infections rates of 114 (25.3%) and 76 (16.9%) respectively. Males were
significantly more infected than females (X2
= 176.4, df = 24, P<0.01).
From the result of the study, the communities surveyed can be said to be
hypoendermic for Onchocerciasis with a nodular rate of 32 (7.1%).
1
CHAPTER ONE
INTRODUCTION
Onchocerciasis, also known as “river blindness” is a disease
caused by a nematode filarial worm. Onchocerca volvulus, and is
transmitted through the bites of an infected female blackfly (Similium
species). The manifestations of onchocerciasis are predominantly
dermal, lymphatic and ocular in character. Dermal, manifestation include
pruritis, lesions (papules, macules, urticaria, oedema, excoriatia
pustules, crusts, scaling ulceration, lichenification, pachydermia,
Atrophy, pigmentary change leopard skin and others) Nodules, lymphatic
manifestations are in form of lymphadenopathy, lyphoedema and
Hanging groin.
Ocular damages affect the conjunctiva, cornea, lens in form of
cataract, Retina in form of pigment epithelial atrophy, cotton wool spots
and Haemorrhages choroid and optic nerves in form of optic neuritis and
optic atrophy (WHO, 1995).
Worldwide onchocerciasis is second to trachoma as a leading
cause of blindness of infectious origin (Thylefors et al 1995). More than
100 million people worldwide are at risk of infection, 18 million people
are infected, 800,000 people are visually impaired, 270,000 people are
2
already blind, 3.3 million of the people reside in Nigeria, where it is still
regarded as a public health problem (WHO, 1995). Blindness which is
the ultimate consequence of onchocerciasis renders the productive
segment of the community unproductive, and dependent on others. Also
most fertile lands have been abandoned because of this disease, (Okolo
et al, 2004).
Onchocerciasis in Nigeria is transmitted solely by members of the
Similium damnosum complex. They are widespread in the savanna
forest, savanna mosaic and rainforest areas of Nigeria. S. damnosum,
which breeds in large streams and rivers in the woody and open country
side, has been known to be common in the rocky sections of the river
Niger and its tributaries (Eneanya and Nwaorgu, 2001). Maikaje et al
(2008) also found S. damnosum breeding along River Muvur and Uba, to
habour infective Onchocerca volvulus microfilarae. In Mubi North and
Hong Local Government Areas of Adamawa State. Okonkwo et al (1991)
found
S. damonsum breeding along the Oji River of Enugu State. Nwoke et al
(1998) also carried out epidemiological studies of human onchocerciasis
in rivers of Katsina Ala (tributary of Benue) Anambra and Oji Rivers
(tributaries of River Niger), the Cross River and Imo River, the costal
3
areas of Rivers, Akwa-Ibom and Cross River States. The exposure of
those rocks in the beds or side margins of these fast flowing rivers as
well as numerous trailing vegetation create favourable breeding sites for
Similium damnosum complex. All these reports indicate that fast flowing
river, rivulets and streams, favours the breeding of blackfly.
A Rapid Epidemiological Mapping of Onchocerciasis carried out in
nine sentinel villages in Edo/Delta (Okhoromi, Ugbokogbe, Oke, Ovao,
Ekilor, Eko-Ibadan, Idumuogo, Agbor Alidinma and Igbogili) recorded a
prevalence of 40.4% of microfilaria infection, 18.9% of nodules and 7.7%
of leopard skin, led to choosing Delta State as an endemic state with
sufficiently important public health problem to warrant community wide
ivermectin treatment, where the prevalence of microfilaria is greater than
40%, (WHO, 1991). Offor et al (1998) trapped blackflies exposed on
human legs between 0600 hours and 18 hours local time in Okpanam
(River Awai) and Ogwashuku (River Mgbiligba) of Delta State and
blackflies were likely forest S. yahense.
The aim of the present study is to determine the current status of
onchocerciasis in selected communities in Aniocha North Local
Government Area of Delta State.
4
The specific objectives include:
1. To define the prevalence of onchocercal nodules in the
communities
2. To define the prevalence of dermatitis in the communities.
3. To define prevalence of leopard skin in the communities and other
clinical manifestations in the communities. It is hoped that the
result will provide useful information on the success of the ongoing
control programme with ivermectin in these areas.
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