Prevalence of Intestinal Schistosomiasis among Residents of Lambu Landing Site, Masaka District Uganda

Table of Contents

DEDICATION

ACKNOWLEDGEMENT

LIST OF ACRONYMNS AND ABBREVIATIONS USED

ABSTRACT

CHAPTER ONE: INTRODUCTION
BACKGROUND
1.1 Global Scale
1.2 African Prevalence
1.3 Ugandan prevalence
1.4 Statement of the problem
1.5 Justification of the study
1.6 General Objective
1.7 Specific objectives

CHAPTER TWO: LITERATURE REVIEW
2.1 Introduction
2.2 Factors Responsible for schistosomiasis
2.3 Life cycle
2.4 Epidemiology
2.5 Schistosomiasis control measures along lake regions and major rivers in Uganda
2.5.1 National Control measures
2.5.2 Current Interventions in the Area

CHAPTER THREE: METHODOLOGY
3.1 Study Design
3.2 Study Area:
3.2.1 Study population:
3.3 Study variables:
3.4 Sampling procedure
3.4.1 Sample size
3.4.2 Sample size estimation
3.4.3 Scope of the study
3.5 Selection Criteria
3.5.1 Inclusion criteria
3.5.2 Exclusion criteria
3.5.3 Ethical Considerations
3.6 Research instruments
3.7 Study procedures:
3.7.1 Assessment Pre-Planning;
3.7.2 Selection of respondents;
3.7.3 Preparation
3.7.4 Procedure.
3.7.5 Precautionary measures during preparation of slides
3.7.6 Quality control
3.7.7 Data collection:
3.7.8 Data management:
3.7.9 Data analysis
3.8 Quality control
3.8.1 Validity and reliability of tools
3.8.2 Validity and reliability of data

CHAPTER FOUR: RESULTS
4.1 Results (Presentation and Interpretation)
4.2 Study Participants
4.3 Participants background information
4.4 Schistosomiasis prevalence
4.5 Factors associated with schistosoma mansoni

CHAPTER FIVE: DISCUSSION
5.1 Discussion
5.2 Conclusion
5.3 Recommendations
5.4 Limitations

LIST OF ACRONYMNS AND ABBREVIATIONS USED

Abbildung in dieser Leseprobe nicht enthalten

DEDICATION

I dedicate this book to my late dad, Jack Mbonye for his support and encouragement to me while still young in the academic world. This book is equally dedicated to the Mbonye family, my wife Judith and dear daughter Ariana. Thank you for the encouragement and motivation that you provided towards the success of this book. To all of you; Iam highly indebted.

ACKNOWLEDGEMENT

The completion of this research dissertation has been a learning process for me and I have learnt a lot from it. I would like to acknowledge the support, encouragement, patience and guidance from a number of people without whom this book would not have been easy to complete.

Iam extremely appreciative to my wife Judith and daughter Ariana for being patient and caring throughout the whole process of this study. Thank you for your input towards the success of this book.

I would like to convey my special gratitude and acknowledgment to my supervisor Mr. Masilili Godfrey Mwarisi who devoted his time for me and paid attention to every detail of this book. Iam so thankful to you because any time I needed to consult, you were always available for me. Thank you.

I wish to acknowledge in a special way the assistance from the training section and the unit management of Medical Research Council for granting me the opportunity to study as I continued working. Without your help this study would not have been possible. I would like to thank in a special way Dr Anatoli Kamali, deputy director MRC; for his encouragement and the deep concern he offered to me throughout the study despite having a very busy schedule, Dr Asiki Gershim, the study coordinator of the fisher folk studies for his guidance, support and encouragement towards the success of this study and Mr. Peter Hughes, the head of clinical laboratories MRC for making my life easy through the whole period that I studied as well as the time for data collection. Thank you so much and keep it up.

I would like to acknowledge and thank my colleagues at work that helped me in one way or the other. I want to thank Mr. Andrew Abasa for his tireless efforts during data analysis, Mr George Segutunga for his encouragement as well as technical assistance during sample analysis, Mr. Kwigyenga Ventus, thank you very much for the role you played during data and sample collection. Special thanks are due to Beleth Kesande, Joyce Nabunya, Ben Gombe, Annet Ajok, and Josephine Namujja for their support in various aspects.

Those who supported in other tasks are also valuable members of the book’s team. Special thanks to Mr Kabengera Sam, Coordinator Mulago Centre, my classmates and all my lecturers.

ABSTRACT

Intestinal schistosomiasis remains a major threat to residents of lambu landing site in Masaka district. Although studies have been done around Lake Victoria region no study has focused on this landing site alone.

With this paucity of data regarding the prevalence of intestinal schistosomiasis at this landing site; the Investigators developed interest to find out the estimated prevalence and the social demographic factors related to Schistosoma infection.

A cross sectional study was carried out between October 2012 and May 2013 to determine the prevalence of intestinal Schistosomiasis at this landing site. A total of 405 respondents aged ten years and above participated in the study. Single stool samples were collected and examined for Schistosoma mansoni ova using the Kato Katz technique.

Majority of the studied participants were Men (59.2%), participants were mostly aged 11-24 years representing 40.3% of the population studied. A large proportion (45.3%) had attained primary education or more and two third (68.2%) had lived in the fishing site for more than 6months. The highest proportion (67.8%) of these participants had never received treatment for Schistosomiasis. Nearly half (45.8%) visit the lake daily and majority (61.2%) use public toilets.

Most of the respondents (37.8%) were engaged in fishing, 16.7% in fish trade and 11.7% in farming. There were nearly equal proportions (33.8%) of the participants engaged in other occupations (especially as students) as there are those engaged in fishing.

The estimated prevalence of Schistosoma mansoni (intestinal Schistosomiasis) in this fishing site was 217/402 representing 54.0%. This prevalence is quite high considering that control measures have been into place for some time.

The results from this study indicate that fishing as an occupation, gender, age; poor toilet utilisation and frequency to the lake shore contribute to the spread of schistosomiasis around Lambu landing site.

The above findings indicate that indeed intestinal schistosomiasis is still a problem considering that control measures have been in place since 2002, the prevalence was generally higher when compared to the general population at 54.0% vs. 47.5%.

The study recommends that all stakeholders involved in the control should opt for a multisectoral approach like massive health education, provision of clean water, ensuring that there are enough well equipped health facilities and qualified health workers in the area. The government policy of providing Praziquantel to the residents should continue but needs to be keenly monitored to ensure that the disease is wiped out.

All these recommendations require combined efforts by different stake holders but largely through increased health funding for neglected tropical diseases like schistosomiasis.

CHAPTER ONE: INTRODUCTION

BACKGROUND

1.1 Global Scale

Schistosomiasis is a parasitic disease caused by blood flukes (trematodes) of the genus Schistosoma. After malaria and intestinal helminthiasis, Schistosomiasis is the third most devastating tropical disease in the world, being a major source of morbidity and mortality for developing countries in Africa, South America, the Caribbean, the Middle East, and Asia (WHO, FEB. 2010).

According to a WHO report in April 2010, more than 207 million people, 85% of who live in Africa, are infected with Schistosomiasis and an estimated 700 million people are at risk of infection in 76 countries where the disease is considered endemic, as their agricultural work, domestic chores, and leisure activities expose them to infested water.

Today, 120 million people are symptomatic with schistosomiasis, with 20 million having severe clinical disease. More than 200,000 deaths per year are due to schistosomiasis in sub-Saharan Africa. (WHO, September 2010).

It has been estimated that 5-10% of an endemic community may be heavily infected, and the remainder has mild to moderate infections. The risk of infection is highest amongst those who live near lakes or rivers. With the rise of tourism and travel, an increasing number of tourists are contracting it. Tourists often present with severe acute infection and unusual problems including paralysis after visiting areas infested with schistosomiasis.

In a study done by Leder & Weller in 2009, it was established that the intensity and prevalence of infection rises with age and peaks usually between ages 15 and 20 years. In older adults, no significant change is found in the prevalence of disease; however, there is a decrease in parasite burden or the intensity.

1.2 African Prevalence

In Africa almost 300,000 people die annually from schistosomiasis in Africa (Van Der Werf et al; 2003). There are an estimated 207 million people infected with one of the major schistosomes, with more than 90% of the cases occurring in sub-Saharan Africa; (Steinmann et al; 2006).

A recent study has confirmed that sites in Africa regularly visited by tourists are commonly reported sites of infection. These sites include rivers and water sources in the Banfora region (Burkina Faso) and areas populated by the Dogon people (Mali); Lake Malawi; Lake Tanganyika; Lake Victoria; the River Omo in Ethiopia; the River Zambezi and the River Nile. However, as visitors travel to more uncommon sites, it is important to remember that most freshwater surface water sources in Africa are potentially contaminated and can be sources of infection. (CDC, 2012)

A study done by King and Dangerfield in 2008 demonstrated that Schistosoma mansoni causes damage to the liver and eventually ends with the chronic morbidities associated with impaired child growth and development, chronic inflammation, anemia, and other nutritional deficiencies, some new disease burden assessments estimate that schistosomiasis accounts for up to 70 million disability-adjusted life years lost annually.

According to a study by Karanja et al;1997; in western Kenya among car washers who were co infected with HIV and schistosomiasis showed that egg excretion for S.mansoni was less compared with individuals who were infected with schistosomes alone although both groups had similar levels of mature adult worms.

1.3 Ugandan prevalence

In Uganda, intestinal schistosomiasis (caused by S.mansoni) is widespread, with highly endemic foci of infection around the water bodies of Lake Albert, Lake Victoria, and Lake Kyoga and along the Albert Nile. It is for this cause that Uganda was the first country where SCI implemented control and henceforth the area upon which this study focuses.

The SCI was established in 2002 with the aim of helping to establish sustainable schistosomiasis control programmes based on large-scale praziquantel administration. The three main areas of schistosomiasis transmission are situated along the shores of Lake Victoria, Lake Albert, and Albert Nile. Monitoring and evaluation areas were chosen using a statistical sampling framework to provide a representative sample of the whole treated area. (Zhang et al; 2007).

According to a study done in 2002, by Narcis et al; 2004 of the Vector Control Division of MOH Kampala between 1998 and 2002 put the national prevalence at 47.5%. The prevalence was 52.9% among males and 40.8 % amongst females.

In Uganda, almost no transmission has been found to have occurred at altitudes greater than 1400 m or where the annual rainfall was less than00 mm according to research done (Kabatereine et al; 2004).

1.4 Statement of the problem

In Uganda, schistosomiasis mainly occurs around the large lakes and rivers, including Lake Victoria, affecting approximately 4 million people, while 16.7 million are estimated to be at risk from the infection according to a study by (Kabatereine et al; 2011).

The enormous ailment associated with schistosomiasis which ranks it next to malaria in terms of public health significance stresses the need for a coordinated and sustainable means for the control of the disease. There is a harmony of opinion that the control of the disease should be integrated.

In Uganda, a programme for the control of intestinal schistosomiasis has been in place since 2003, coordinated by the Vector Control Division of the Uganda Ministry of Health, with support from the SCI but the disease burden is still evident around lake regions in the country.

In 2007, the district of Masaka was added to the number of districts receiving mass drug administration of praziquantel among residents living on the shores of Lake Victoria, Despite all these control efforts directed towards elimination of this disease burden the disease does not seem to go down, a recent study done among Fisher Folk communities co infected with S. mansoni and HIV in 2009 along Lake Victoria shores put the prevalence at 50%. The recent research was conducted among HIV positive residents; it is possible that the prevalence could even be higher in the population along the lake shores and hence the need for this study.

1.5 Justification of the study

In the year 2000, it was estimated that 35 million people in Africa were directly engaged in fishing as either full or part time (FAO, 2002)

The economic and health effects of schistosomiasis are significant. Chronic schistosomiasis may affect people’s ability to work and in some cases can result in death. In sub-Saharan Africa, more than 200 000 deaths per year are due to schistosomiasis (WHO, September, 2010).

Illness is often caused by eggs rupturing the intestinal wall leading to blood loss and subsequent anaemia, and the immune response to eggs that become trapped in organs and tissues, leading to the development of hepatomegaly, splenomegaly, and eosinophilia.

In Uganda approximately 2.5 million are engaged in the fisheries sector. The sector in Uganda contributes to food security, foreign exchange, employment and local government revenue. Fishing is therefore a major source of livelihood for rural communities situated around Lake Victoria and other small lakes in Uganda (Allison & Ellis, 2001).

Despite the sector supporting the many livelihoods as a source of food and employment, schistosomiasis infections remain a major threat to their survival and existence. Schistosomiasis control programmes have tried to bring down the disease without much success and therefore the need to carry out further surveys to find out why the disease remains a threat to populations living along major lakes such as L. Victoria.

1.6 General Objective

To determine the prevalence of S.mansoni among residence of Lambu landing site along the shores of Lake Victoria.

1.7 Specific objectives

1. To determine the number of people with Schistosoma ova in their stool samples.

2. To establish the occupation of the participants in relation to the results obtained.

3. To determine the association between social demographic factors and Schistosoma infection

CHAPTER TWO: LITERATURE REVIEW

2.1 Introduction

Schistosomiasis is a chronic, parasitic disease caused by blood flukes (trematodes worms) of the genus Schistosoma. At least 230 million people require treatment every year. Schistosomiasis transmission has been documented in 77 countries. However, those at most risk of infection are in 52 countries. (WHO, 2012). In Uganda, schistosomiasis mainly occurs around the large lakes and rivers, including Lake Victoria, affecting approximately 4 million people, while 16.7 million are estimated to be at risk from the infection according to Kabatereine et al; (2011). The species of Schistosoma that can infect humans are Schistosoma mansoni and Schistosoma intercalatum which cause intestinal schistosomiasis; Schistosoma haematobium causes urinary schistosomiasis; Schistosoma japonicum Schistosoma mekongi causes Asian intestinal schistosomiasis.

Schistosomiasis is sometimes referred to as bilharzias, bilharziasis, or snail fever, it was discovered by Theodore Bilharz, a German surgeon working in Cairo, who first identified the etiological agent Schistosoma hematobium in 1851(Nawal, 2010). The number of people treated for schistosomiasis rose from 12.4 million in 2006 to 33.5 million in 2010. People are at risk of infection due to agricultural, domestic and recreational activities which expose them to infested water. Hygiene and play habits make children especially vulnerable to infection. Clean drinking water and adequate sanitation would reduce infective water contact and the contamination of water sources. Schistosomiasis control focuses on reducing disease through periodic, targeted treatment with praziquantel.

2.2 Factors Responsible for schistosomiasis

The factors responsible for schistoma infections along lake regions and other water bodies are grouped into biological, socioeconomic and behavioral factors. Host exposure and host immunity accelerate the disease burden. Both factors demonstrate marked heterogeneity within any given population (Butterworth 1994). The reasons for this heterogeneity are variable and may involve nutritional, genetic and socio-cultural factors. As a behavior related disease, the risk of infection with schistosomiasis is associated to age, sex, and occupation of individuals (Gryseels, 1991). The conditions responsible for the evolution to the severe forms of the disease are not completely clear although the parasite burden seems to be a major determinant (Sleigh et al; 1986). In addition, the contribution of other factors on morbidity in schistosomiasis, including host and parasite genetics, other infections and nutritional status, are still poorly understood (WHO, 1992).

The spread of schistosomiasis requires the efficiency of an intermediate snail host of the molluscan species (Biompilaria responsible for S. mansoni and Oncomelania for S. haematobium). It is therefore particularly found along lake regions and along major rivers; it affects mainly children but also adults with particular occupations like fishing and Irrigation related agriculture.

A study by Standley et al; 2009 suggested that the eastern part of Lake Victoria is known to be a highly endemic zone for intestinal schistosomiasis. The other factors influencing the prevalence along the lake shores are environmental factors that influence snail distribution which are often overlooked, despite the fact that these can vary considerably from site to site and area to area. Among the physical and chemical variables measured in the study was water temperature which seemed to be the key determinant of snail abundance. There is a positive association between snail abundance and water temperature. The molluscan species are predominant in areas with high temperatures (Stensgaard et al; 2006).

Another research done by Kariuki et al; (2004) revealed that pH affects snail distribution; snails were found in sites with pH ranging from 6.7 to more than 11. It has been suggested that such high pH values may be caused by human contaminants such as cleaning products and faecal matter again citing poor sanitation as having an impact in snail abundance.

2.3 Life cycle

The life cycles of all five human schistosomes are broadly similar: parasite eggs are released into the environment from infected individuals, hatching on contact with fresh water to release the free-swimming miracidium. Miracidia infect fresh-water snails by penetrating the snail's foot. After infection, close to the site of penetration, the miracidium transforms into a primary (mother) sporocyst. Germ cells within the primary sporocyst will then begin dividing to produce secondary (daughter) sporocysts, which migrate to the snail's hepatopancreas. Once at the hepatopancreas, germ cells within the secondary sporocyst begin to divide again, this time producing thousands of new parasites, known as cercariae, which are the larvae capable of infecting mammals. People become infected when larval forms of the parasite – released by freshwater snails – penetrate their skin during contact with infested water. In the body, the larvae develop into adult schistosomes. Adult worms live in the blood vessels where the females release eggs. Some of the eggs are passed out of the body in the faeces or urine to continue the parasite life-cycle. Others become trapped in body tissues, causing an immune reaction and progressive damage to organs according to News-Medical.Net 2012

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https://www.cdc.gov/parasites/schistosomiasis/biology.html

2.4 Epidemiology

According to a WHO report of April 2010, globally about 230 million people are infected and more than 207 million people, 85% of these who live in Africa, are infected with Schistosomiasis .An estimated 700 million people are at risk of infection in 76 countries where the disease is considered endemic, as their agricultural work, domestic chores, and recreational activities expose them to infested water.

About 120 million people infected with schistosomiasis are estimated to be symptomatic while about 20 million develop severe disease. It is estimated that more than 200,000 deaths per year are due to schistosomiasis in sub-Saharan Africa (WHO, September, 2010). The disability adjusted life years due to schistosomiasis is about 1.7-4.5 million while between 150,000 to 280,000 people are known to die as a consequence of schistosomiasis per year. Africa accounts for 85% of the disease burden Steinmann et al; (2006)., World Health Organisation (2002). Urinary schistosomiasis has been reported in 38 countries in Africa. Annual mortality due to S. haematobium infection in east Africa has been estimated at 1 per 1000 infected adults according to a report by the World Health Organisation (1993). In Malawi, save the children’s 1998 survey of schoolchildren in Mangochi found that the overall prevalence of schistosomiasis in coastal and upland schools was 36%. In some of the schools, the prevalence was as high as 87% in a study by Bobrow (1999). In a related study in Cameroon, Mba and Useh (2008) reported that urinary schistosomiasis among subjects studied was 39.2%. Mixed infection of S. haematobium and S. mansoni occurred in 4.5% of the subjects. The number of infected subjects treated for the disease using praziquantel rose for 12.4 million in 2006 to 33.5 million in 2010. It is estimated that 90% of those that require treatment live in Africa. This implies that over 60% of people suffering from schistosomiasis particularly in Africa are not able to procure treatment or have access to treatment due to the relatively high cost of praziquantel.

Schistosomiais is prevalent in tropical and sub-tropical areas, especially in poor communities without access to safe drinking water and adequate sanitation. It is estimated that at least 90% of those requiring treatment for schistosomiasis live in Africa.

There are two major forms of schistosomiasis – intestinal and urogenital – caused by five main species of blood flukes. S.mansoni is prevalent in Africa, the Middle East, the Caribbean, Brazil, Venezuela and Suriname. Schistosoma japonicum is found mainly in China, Indonesia, and the Philippines. Schistosoma mekongi is widespread in several districts of Cambodia and the Lao People’s Democratic Republic Schistosoma quineensis and related Schistosoma intercalatum are common Rain forest areas of central Africa. Schistosoma haematobium is found in Africa, the Middle East. (Cheesbrough, 1998). The distribution of schistosomiasis is very focal and determined by the presence of competent snail vectors, inadequate sanitation, and infected humans. The geographic distribution of cases of schistosomiasis acquired by travelers reflects travel and immigration patterns. Most travel-associated cases of schistosomiasis are acquired in sub-Saharan Africa.

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Photograph: Courtesy of the Fisher folk study MRC/UVRI 2009

Schistosomiasis particularly affects agricultural and fishing populations. Women undertaking domestic chores in infested water, such as washing clothes, are also at risk. Hygiene and playing in mud and water make children vulnerable to infection. Forty million women of childbearing age are infected. (Friedman et al; Apr 2007)

According to the United States centers for disease and prevention (CDC, 2012), approximately 10 million women in Africa have schistosomiasis.

According to a study done in 2002, by Narcis et a l; 2004 of the Vector Control Division of MOH Kampala between 1998 and 2002 put the national prevalence at 47.5%. The prevalence was 52.9% among males and 40.8 % amongst females.

In Uganda, almost no transmission has been found to have occurred at altitudes greater than 1400 m or where the annual rainfall was less than00 mm according to research done (Kabatereine et al; 2004).

2.5 Schistosomiasis control measures along lake regions and major rivers in Uganda

2.5.1 National Control measures

To fight schistosomiasis at the national level, efforts to control the disease have been initiated in some areas. Chemotherapy with praziquantel is currently the basis of control, which is accessible at a low cost (Doenhoff et al; 2008; Fleming et al; 2009). Uganda has had a national control programme in place since 2003, initiated in corporation with the SCI, Kabatereine et al; (2006b). This control programme first classified at-risk districts using maps and historical data, focusing on large lakes such as Victoria, Albert and Kyoga.Actions of risk were based on baseline infection surveys, malacological data and, more recently, satellite data which can be shared with other sources to create longitudinal risk maps in a geographical information system software (Brooker et al; 2001; Kabatereine et al; 2004; Stensgaard et al; 2006; Brooker, 2007). By means of these data, a pilot control programme of yearly large-scale administration of PZQ to all primary school children within a selected sub district was then rolled out. Schools were selected for treatment based on the increased benefits of reducing infection burdens in children compared to adults and also due to the simplicity of providing treatment (Kabatereine et al; 2007; Zhang et al; 2007). The programme was expanded in 2004 to include treatment with albendazole against common soil-transmitted helminth infections such as hookworm, Ascaris lumbricoides and Trichuris trichiura (Kabatereine et al., 2006a). The 5-year initial run of the programme was completed in 2009, ending SCI’s initial involvement , Fenwick et al; (2009). The Ugandan government is committed to maintaining the programme with continued support and another new funding supported by USAID

2.5.2 Current Interventions in the Area

In 2007, Masaka and Mpigi districts were added to the list of districts receiving MDA, based on data showing increased disease levels as compared to the original 2003 baseline data (Kabatereine et al; 2007). The survey revealed that despite regular chemotherapy and educational interventions, levels of intestinal schistosomiasis were still very high in these areas. The only exception was Rakai district, which continues to have low, almost negligible, levels of S. mansoni despite it being close to Masaka district. This data supported earlier evidence of a geographical west to east cline along Uganda's Lake Victoria shoreline of increasing schistosomiasis prevalence, although the observation of significant local heterogeneities should be taken into consideration. The reasons for this alleged observation may be related to climatic variation along the lakeshore, or certainly differences in population density or sanitation infrastructure; according to a related study by (Clements, et al; 2010).

Treatment availability and capacity building in Masaka district was affected by absence of volunteers willing to take on the role of community medicine distributors CMDs.The reasons given for refusals included distances between the sites and lack of adequate funding for travel while in some islands in Kalangala some inhabitants have refused to take PZQ due to experiencing severe side effects after swallowing the drug (Kabatereine et al; 2011).

In a recent study by Kaleebu et al; (2009) it was acknowledged that schistsomaisis and HIV co-infections were high among fishing communities along the shores of Lake Victoria. The study placed the prevalence rate at 50% and hence recommended further investigations into HIV and worm infections.

This study targeted HIV infected individuals and therefore affects the quality of life in these disadvantaged communities along the lake shores.

In a study done by Kabatereine et al; (2007), it was clear that prevalence of intestinal schistosomiasis, STH and malaria continued to be high in many of the islands and the districts bordering on Lake Victoria including Masaka. Consequently, the National Control Programme, which has been effective in reducing intensity and disease-related morbidity, needs to improve treatment coverage and efficacy of existing control measures in the areas covered by the study.

Public health workers are often required to travel, by wooden canoes for several hours, to reach the shores and outer islands in the lake; fuel for canoe engines is expensive, and often unavailable. Another challenge facing the treatment programmes is the high level of population movements and migration throughout the region; this has been observed in other studies Standley et al; (2009) and migration is cited as a key reason for treatment coverage during the survey only being estimated at approximately 70%. This places interest to include measures of itinerancy in future studies, for accurate documentation of the scale of population movement in the region. A solution will be to provide adequate funding to local health officers for local travel; however, even if such funds were available, supervision and accountability of the system should concurrently improve in order to ensure the investment reaches the people who need it the most.

In another earlier study by Utzinger et al; (2003), funding was cited as a key factor in eradicating schistosomiasis around Lake Victoria basin. The question of funding, and in particular, sustainability of control initiatives is essential in creating an effective and efficient programme for reducing disease burden. Although chemotherapy is the strength of control tactics up to now, it is clear that MDA alone will not sufficiently eradicate transmission of schistosomiasis, especially in hyper-endemic areas such as the Lake Victoria shores and islands. What is required is a combination of political will, health education and improvements in access to good sanitation and clean water, alongside a committed and consistent chemotherapy regime.

There is therefore a need to carry out further research and try to find out why despite these interventions by the Ugandan government and other international organizations in these areas the disease continues to exist up to today

CHAPTER THREE: METHODOLOGY

3.1 Study Design

The study was a cross sectional observational study to determine the prevalence of schistosomiasis among residents of Lambu landing site along the shores of Lake Victoria in Masaka district.

3.2 Study Area:

The study was conducted at Lambu landing site which is located in Bukakata subcouty in Masaka district on the western shores of Lake Victoria along the Masaka- Kalangala road. Bukakata is located approximately 44 kilometers (27 miles), by road, east of Masaka town. This location is approximately 65 kilometres (40 miles), by boat, southwest of Entebbe. The coordinates of the town are: 00 18 18S, 32 02 24E (Latitude: -0.3050; Longitude: 32.0400).

Stool samples were collected from Lambu landing site and transported to the MRC laboratories in Masaka where analysis was performed.

3.2.1 Study population:

The study population was aged 10 years and above residing in Lambu. The respondents used in the study had lived in this locality for at least for three months.

3.3 Study variables:

This study had the following variables;

-Stool preparation slides results for S. mansoni ova i.e. Positive or Negative.

-Demographical data of the respondents.

-Symptoms if any

-Management or treatment of previous Schistosomiasis infection.

3.4 Sampling procedure

A probability sampling was utilized. Only individuals who fell in even numbers were selected. A list of participants was made and then even numbers were picked out.

3.4.1 Sample size

The study was conducted at Lambu landing site along the shores of L. Victoria in Masaka district, Uganda. The sample size used was 367 participants aged between 10 years and above. The study targeted residents as well as commercial traders in fish who had lived in the area for at least 3 months; since this give them ample time for exposure to the infection. Stool samples were collected from each respondent once.

3.4.2 Sample size estimation

The sample size N was obtained according to the standard deviation formula derived by Kish &Lesle (1965)

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Z= Parameter standard for a normal distribution curve at α= 0.05

P=the proportion /prevalence of S. mansoni estimated to be 47.5 % (Narcis B et al 2004).

N=Sample size

1-P= (complement of the estimated prevalence)

W=margin of error /boundary of error = 5%

From the standard normal distribution curve z=1.96.

The estimated prevalence (p) =0.475, (1-P) =0.525, w=0.05

Substituting in formula (i) above

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Adjusting for refusals by 5% n=384X1.05=403 participants.

3.4.3 Scope of the study

The study was done to determine the number of people who are 10 years and above with S.mansoni in their stool. The study commenced in October 2012 and ended in May 2013.

The study was carried out at Lambu landing site which is located in Bukakata subcouty in Masaka district on the western shores of Lake Victoria approximately 44 kilometers (27 miles), by road, east of Masaka town.

The study used the residents as the independent and the presence of schistosomiasis as the dependent variables.

3.5 Selection Criteria

3.5.1 Inclusion criteria

- Participants who were selected were those able and willing to provide informed consent

- Participants aged 10 years and above were selected.

- Only Participants who were residents of Lambu landing site were selected.

3.5.2 Exclusion criteria

- Should not have had any condition that would preclude him to provide informed consent for example mental illness.

- Should not have been on treatment for schistosomiasis disease

3.5.3 Ethical Considerations

Ethical clearance was obtained from the Ethics committee of Mbarara University of science and Technology Faculty of Medicine. After explaining the importance of the study briefly an informed written consent was obtained from the study participants. Any participant not willing to take part in the study had the freedom to do so. Confidentiality was maintained at all times during the study. The information obtained only served the purpose of this study and no names were used.

3.6 Research instruments

The research collection tools will utilize

- Questionnaires
- Lab tests and worksheets.
- checklists
- Microscope
- Microscope slides
- Stool examination kit/Kato Katz Equipment

3.7 Study procedures:

3.7.1 Assessment Pre-Planning;

Discussions were held with the local council leadership on how participants would be identified from different locations. This was to determine the research point for data collection. This was appropriate since the researcher was collecting the data alone. Staffs in different clinics where respondents seek treatment were informed about the study and requested to refer some of the people they suspected to have had schistosomiasis.

3.7.2 Selection of respondents;

Respondents aged 10 years and above were requested to converge at common place within the locality. Those willing were told about the research processes and benefits and were requested to fill and sign the consent form.

After consenting the respondent were given a number and that number was put on the questionnaire. The respondent was requested to respond to the questions in the questionnaire which were being asked by the researcher.

A Stool sample was collected from him/her. Kato Katz technique was used and results were recorded in the result reporting form.

The procedure for the technique was adopted from the WHO manual of 2005.

3.7.3 Preparation

An appropriate number of nylon screens 30-35mm were cut.

An appropriate number of pieces of hydrophilic cellophane of 30-35mm were and placed it in a jar.

Glycerol was poured on to the cellophane strips placed in the jar and left for at least 24 hours. To increase the viability of the eggs, I ml of 3% aqueous malachite green or 3% methylene blue was added to the glycerol solution.

3.7.4 Procedure.

Place a small amount of faecal material on the scrap paper and place a piece of nylon screen on top so that some of the faeces are sieved through the screen and accumulated on top.

Scrap the flat sided spatula across the upper surface of the screen to collect the sieved faeces

Place the temperate on the centre of the microscope slide and add faeces from the spatula so that the hole is completely filled. Pass over the template using the side of the spatula to remove excess faeces from the edge of the hole Remove the template carefully so that the cylinder of faeces is left on the slide Cover the material with pre-soaked cellophane strip, the strip must be very wet if the faeces are dry and less so if the faeces are soft.

Invert the microscope slide and press the faecal sample firmly against the hydrophilic cellophane strip on another microscope slide. The faecal material will be spread evenly between the microscope slide and the cellophane strip. It should be possible to read a newspaper print through the print after clarification.

Carefully remove the slide by gently sliding it side ways to avoid separating the cellophane strip or lifting it off. Place the slide on the bench with the cellophane upwards, water will evaporate as the glycerol clears the faeces.

Keep the slide for one or more hours at room temperature to clear the faecal material, prior to examination under the microscope. To speed up clearing the slide can be placed in an incubator at 400C or kept in direct sunlight for several minutes. Examination will then be done using ×5, ×10 and finally ×40 objectives.

Schistosome eggs are recognizable for up to several months but examination will be done within 24 hours after preparation.

The smear will be examined in a systemic manner and the number of eggs reported. Later multiply this number by 24 to obtain the epg

The epg gives an estimation of the worm burden and allows identifying individuals likely to suffer from severe significances of the infection i.e. these with heavy infestations.

3.7.5 Precautionary measures during preparation of slides

The slides were labeled using a permanent cryoware marker. The preparation of smears was done in the class I safety cabinet.

3.7.6 Quality control

Daily IQC was carried out using known positive and known negative smear for S.mansoni ova and this was performed each day before samples were examined.

Known positive and negative Kato Katz smears were treated in the same manner as the test slides. The positive control was used to check on the method and quality of the preparation while the negative control was used to confirm the specificity of the technique.

Fresh preparation of malachite green was changed weekly. 10% of the slides were proof-read by experienced laboratory staff.

3.7.7 Data collection:

All the respondents within the inclusion criteria were given a number. This number started from 2 then 4 up to the last respondent number.

The data was collected depending on the variables that were collected; Demographic data was captured in the questionnaire.

Stool results were recorded as follows; (Pos) for positive and (Neg) for negative smears. These were entered in the forms.

3.7.8 Data management:

Completed filled questionnaires and data collected from all the respondents were checked and stored safely at the end of each day. The data was handled by the researcher only and was written by the use of a pen.

3.7.9 Data analysis

Data from every participant was recorded on a worksheet and thereafter double entry done for accurateness in database created in MS Access for validation and then analyzed using SPSS for window version 11.5 (SPSS Inc., Chicago, IL, USA). An arithmetic mean egg count from two Kato‐Katz thick smears was calculated for S. mansoni. Infections intensity of

S. mansoni was classified according to WHO criteria; light intensity infections (1-99 epg), Moderate intensity infections (100-399), Heavy intensity infections (≥ 400epg) (WHO, 1991; WHO, 2005). Data was then entered in tables, Pi charts and graphs.

3.8 Quality control

3.8.1 Validity and reliability of tools

The questionnaire was formulated in English and interpreted into Luganda if the participant did not understand English by the researcher who knew both English and Luganda.

The questionnaire was pretested before administration to the respondents in order to obtain appropriate facts from the participants.

3.8.2 Validity and reliability of data

Test-retesting of kept slides was conducted by an experienced parasitologist on site. Additionally, a few slides (10%) were sent to MRC parasitology lab every week in order to assess the validity and reliability of the results produced. The SOPs in place were used to minimize on errors during analysis.

Triangulations were carried out to ensure quality, validity and reliability of the findings. This was done by repeating the same research interview with the same respondent on the same topic at different intervals but by a different interviewer. The answers that were given by the respondent using two different interviewers had to be the same or very close in order to reduce bias and errors.

CHAPTER FOUR: RESULTS

4.1 Results (Presentation and Interpretation)

4.2 Study Participants

A total of 405 participants consented to participate in the study. Of these 402 (99%) provided stool samples for Schistosomiasis examination. The remaining 3(1%) participants were excluded from this analysis due to mislabeled stool samples. This chapter presents data from the 402 participants with full stool examination results.

4.3 Participants background information

As indicated in table 1 below, most (59.2%) of the studied participants were Men, participants were mostly aged 11-24 years representing 40.3%. A large proportion (45.3%) had attained primary education or more and two third (68.2%) had lived in the fishing site for more than 6months. The highest proportion (67.8%) of these participants had never received treatment for Schistosomiasis. Nearly half (45.8%) visit the lake daily and majority (61.2%) use public toilets table1.

Table 1: Background to characteristics of the studied volunteers

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In the graph 1 below, most (37.8%) were engaged in fishing, 16.7% in fish trade and 11.7% in farming. There were nearly equal proportions (33.8%) of the participants engaged in other occupations as there are those engaged in fishing.

Graph 1: Showing occupations of the studied participants

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4.4 Schistosomiasis prevalence

The estimated prevalence of Schistosoma mansoni (intestinal Schistosomiasis) in this fishing site was 217/402 (54.0%). The average egg count was estimated to be 414.5per gram while the median was 216 per gram. The minimum egg count was 24 while the maximum was 5040.

Graph 2: Showing Schistosomiasis prevalence

Abbildung in dieser Leseprobe nicht enthalten

4.5 Factors associated with schistosoma mansoni

The prevalence of schistosoma mansoni was by far higher among men compared to women (68.9% vs 32.3%). This difference was statistically significant p<0.01 table 2. Though there was no statistical significance between schistosoma infection and age group p=0.51, the prevalence was higher among the younger participants (57.4%) in those aged 11-24 years and lowest (50.5%) among those aged more than 24years. Nearly equal prevalence of schistosoma (52.7% vs 55.5% vs 52.7%) were observed among those with no education at all, primary and secondary or more education respectively. This difference did not reach a statistical significance p=0.86. Participants engaged in fishing had the highest prevalence of schistosoma mansoni (75%) compared to those in fish trade (26.9%), farming (38.3%) and other occupations (49.3%) p<0.01. Participants that had stayed in the fishing site for more than 6months had the highest prevalence (58.8%) of schistosoma mansoni compared to those staying 3-6 months (49.5%) and at most 3 months (24.1%) p<0.01. Nearly equal prevalence (59.2% and 60.0%) was observed among participants that had never received treatment for schistosoma mansoni and those that did not know or refused to respond to this exploration respectively. This prevalence significantly (p<0.01) differed from that (42.7%) observed in those that had previously received treatment for schistosoma mansoni. The prevalence was statistically significant p<0.01 between participants that visit the lake daily (75.0%) compared to 54.1% and 32.1% among those that visit the lake once a week and once a month respectively. The prevalence of schistosoma mansoni was significantly higher among participants that refused to respond to the investigation on ownership of public toilet (86.7%), having no toilet (61.8%) and use of public toilet (56.1%) compared to having a toilet (32.9%) p<0.01 table 2.

Table 2: Factor associated with the Schistosomiasis( Prevalence by factors )

Abbildung in dieser Leseprobe nicht enthalten

CHAPTER FIVE: DISCUSSION

5.1 Discussion

This study has established that among 402 participants studied, 54.0% were positive for intestinal schistosomiasis and 46.0% were negative. These results indicate that Schistosomiasis is still abundant around Lambu landing site on the shores of Lake Victoria.

The findings of the current study agree with results observed by several other researchers regarding the estimated prevalence of schistosomiasis being higher among fishing communities along Lake Victoria. The national survey carried out in 2002, by Kabatereine et al; 2004 of the Vector Control Division of MOH Kampala between 1998 and 2002 placed the national prevalence at 47.5%. The prevalence was 52.9% among males and 40.8 % amongst females.

In a related study by Kaleebu et al; 2009 it was acknowledged that schistsomaisis and HIV co-infections were high among fishing communities along the shores of Lake Victoria. The study found out that the prevalence was about 50% among the residents around the landing sites.

In Malawi, save the children’s 1998 survey of school children in Mangochi found that the overall prevalence of schistosomiasis in coastal and upland schools was about 36%. In some of the schools, the prevalence was as high as 87% in a study by Bobrow in 1999.

In a related study in Cameroon, Mba and Useh (2008) reported that urinary schistosomiasis among subjects studied was 39.2%. Mixed infection of S. haematobium and S. mansoni occurred in 4.5% of the subjects.

Although this study is slightly higher than the national of 2002 and a recent study by Kaleebu et al; 2009 it is still apparent that the prevalence rate is generally high. The other facts could be that this study only focused on one landing site as well as high population movements along this Lake Victoria shoreline.

Schistosomiasis was observed in 54.0% of the residents studied and this closely in agreement with the national statistics on Schistosomiasis with a prevalence of 47.5%.

The prevalence was higher among residents with fishing as their major occupation (75. 0%).This is in agreement with a study by Friedman et al, Apr 2007 which indicated that the prevalence was higher among fishermen and those engaged in irrigation- agriculture related activities

It is important to note that among residents who had received treatment in the last two years, about 42.7% still had the infection. This brings in another challenging question either they did not completely heal from the infection or were treated successfully or got re- infected again. This may be due to the fact that some people refuse to take PZQ owing to experiencing severe side effects after swallowing the drug ;( Kabatereine et al; 2011).

Also noted was the high number of cases with the infection in residents who either did not have a toilet at home and those who used public toilet at the landing site at 61.8% and 56.1% respectively. This is in agreement with a study by Utzinger et al; 2003 which stresses that PZQ alone without other control measures cannot eliminate the disease.

5.2 Conclusion

The results of this study shows that Intestinal Schistosomiasis is still a big problem among residents of Lambu landing site on the western shores of Lake Victoria. Despite the national control measures in the country; the prevalence at this landing site is astonishing! The gender, duration of stay around the landing site, occupation of the residents, Lack of health education among the locals coupled with a high population without adequate sanitation appears to contribute for this high prevalence.

5.3 Recommendations

The Ugandan government should consider schistosomiasis a serious health concern around this landing site. The problem requires a multisectoral approach through increase in the health budget, seeking donor help in order to priotise the control of neglected tropical diseases which are still a threat to the local population. Current efforts directed towards infected residents using Praziquantel should continue but also other measures towards snail intermediate hosts, ecological alterations, health education and the provision of piped water should be thought of as an alternative as long as they can be afforded.

Simple water storage and other modification measures like simple resting of water for 24 hours, crude filtration methods and introduction of mild disinfectants can render the schistosome cercariae ineffective. These should be encouraged through health education programmes.

The landing sites along Lake Victoria and other major lakes in Uganda should be included among priority areas that deserve clean piped water to prevent the local population from coming in contact with infected water.

The SCI and the Ugandan government should think of ways to detect the disease early and on regular basis through rapid diagnostic tests in individuals prone to the infection like fishermen

5.4 Limitations

There were delays in approval to start the study both from Mbarara University of Science and Technology as well as my employer. I had to request for time off duty since the landing site is about 44 Km from Masaka, my place of work. I want to acknowledge my employer for permitting me an opportunity to collect the samples required for this study.

Some of the participants did not provide adequate stool samples for analysis and in some cases some of the samples were mislabeled by my field assistant and such samples did not form part of the study, never the less he did a commendable job towards the success of this research thesis.

Failure to collect stool samples twice; this could have provided more accurate results as one stool sample may be misleading especially when a result is negative.

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