Fikireselassie Samuel.pdf - Addis Ababa University

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1. INTRODUCTION Helminth infections caused by soil-transmitted helminths (STHs) and schistosomes are among the most prevalent infections of humans living in areas of poverty in the developing world. The morbidity caused by STH and schistosomes is most commonly associated with infections of heavy intensity. Approximately 300 million people with heavy helminth infections suffer from severe morbidity that results in more than 150,000 deaths annually (Crompton, 1999 and Montresor et al., 2002). In addition to their health effects, helminth infections also impair physical and mental growth in childhood, thwart educational advancement, and hinder economic development. The four most common STHs are roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura,), and the anthropophilic hookworms (Necator americanus and Ancylostoma duodenale). De Silva et al. (2003) reported that, A. lumbricoides infects 1.221 billion people, T. trichiura 795 million, and hookworms 740 million. They are considered together because it is common for a single individual, especially a child living in a less developed country, to be chronically infected with all the three worms. Such children have malnutrition, growth stunting, intellectual retardation, and cognitive and educational deficits (WHO, 2005). STHs are a group of parasitic nematode worms causing human infection through contact with parasite eggs or larvae that thrive in the warm and moist soil of the world’s tropical and subtropical countries. As adult worms, the soil-transmitted helminths live for years in the human gastrointestinal tract. More than a billion people are infected with at least one species (WHO, 2005). Despite their educational, economic, and public-health importance (panel), STHs remain largely neglected by the medical and international community. This neglect stems from three features: first, the people most affected are the world’s most impoverished, particularly those who live on less than US$2 per day; second, the infections cause chronic ill health and have insidious clinical presentation; and third, quantification of the effect of soil-transmitted helminth infections on economic development and education is difficult (Chan, 1997). 1 Created by PDF Generator (http://www.alientools.com/), to remove this mark, please buy the software.
Studies have highlighted the profound effect of STH infections on school performance and attendance and future economic productivity (Bleakley, 2003). The infections might also increase host susceptibility to other important illnesses such as malaria, tuberculosis, and HIV infection (Fincham et al., 2003). 1.1. Burden of Soil-transmitted Helminthiasis STH infections are among the most prevalent and widespread chronic human infections worldwide (Stoll, 1999). STHs are with the greatest public health burden occurring in developing countries, particularly in sub-Saharan Africa (Bethony et al., 2006). The majority of these infections result from low standard of living, poor socioeconomic status, poor personal hygiene, and poor environmental sanitation (Bundy and Gutatt, 1996). STH infections are widely distributed in tropical and sub-tropical areas, especially in poor populations. For all human soil-transmitted helminths studied to date, which so far includes Ascaris, Trichuris, both hookworms, Enterobius, and Ternidens, worm burdens exhibit a highly overdispersed distribution so that most individuals harbor just a few worms in their intestines while a few hosts harbor disproportionately large worm burdens (Bundy, 1995). These heavily infected individuals are simultaneously at highest risk of disease and the major source of environmental contamination (Bundy, 1995). In the case of Ascaris and Trichuris infections, overdispersed distributions also exhibit age dependency, with a peak in the childhoods, but with a subsequent decline among adults (Bundy, 1995). Maximum prevalence of both Ascaris and Trichuris infections is usually attained before 5 years of age (Bundy, 1995). Numerous studies covering a diversity of geographic regions worldwide also indicate that for Ascaris and Trichuris infections maximum worm burdens occur in human populations at 5-10 years of age (Bundy, 1995). Although heavy hookworm infections occur in childhood, frequency and intensity commonly remain high in adulthood, even in elderly people (Bethony et al., 2002). 2 Created by PDF Generator (http://www.alientools.com/), to remove this mark, please buy the software.
Page 1 and 2: ADDIS ABABA UNIVERSITY FACULTY OF L
Page 3 and 4: 5.3.Sample Size Determination……
Page 5 and 6: List of Tables Table 1: Classes of
Page 7 and 8: List of Abbreviations and Acronyms
Page 9: ABSTRACT The three major soil-trans
Page 13 and 14: Infection with T. trichiura (trichu
Page 15 and 16: 1.3. Soil-transmitted Helminth Infe
Page 17 and 18: educe morbidity and avoid mortality
Page 19 and 20: (ATP), which is the energy required
Page 21 and 22: 1.5.4. Mechanism of Anthelminthic D
Page 23 and 24: National prevalence of hookworm is
Page 25 and 26: 4. OBJECTIVES 4.1.1. General Object
Page 27 and 28: (Richter, 2003). The data collected
Page 29 and 30: 5.5. Assessment of Post-treatment S
Page 31 and 32: 5.8. Ethical Considerations This st
Page 33 and 34: Table 2. Demographic characteristic
Page 35 and 36: 6.2. Cure Rate Cure rate is defined
Page 37 and 38: and 78.6 %( 33) of abdominal pain w
Page 39 and 40: factors as high treatment frequency
Page 41 and 42: 8. CONCLUSIONS AND RECOMMENDATIONS
Page 43 and 44: Bethony, J., Chen, J. and Lin, S. (
Page 45 and 46: Hotez, P.J., Zhan, B. and Bethony,
Page 47 and 48: school-age children in Kabale Distr
Page 49 and 50: WHO (2006a). Preventive chemotherap
Page 51 and 52: Appendix 2: Questionnaire to Survey
Page 53 and 54: 11. DECLARATION I, the undersigned,

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