SYMPTOMS AND CONTROL OF SCHISTOSOMIASIS INFECTION
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. Lack of hygiene and certain play habits of school-aged children such as swimming or fishing in infested water make them especially vulnerable to infection. Acute symptoms of intestinal schistosomiasis include abdominal pain, diarrhoea, and blood in the stool. In chronic cases liver enlargement and is frequently associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels. Acute Symptoms of urogenital schistosomiasis is haematuria (blood in urine). Fibrosis of the bladder and ureter, and kidney damage are sometimes diagnosed in advanced cases. In women, urogenital schistosomiasis may present with genital lesions, vaginal bleeding, pain during sexual intercourse, and nodules in the vulva. In men, urogenital schistosomiasis can induce pathology of the seminal vesicles, prostate, and other organs. Chronic symptoms are bladder cancer. This disease may also have other long-term irreversible consequences, including infertility. Schistosomiasis control focuses on reducing disease through periodic, large-scale population treatment with praziquantel; a more comprehensive approach including potable water, adequate sanitation, and snail control would also reduce transmission.
TABLE OF CONTENTS
Title page i
Chapter One: Introduction 1
Chapter Two 4
Symptoms of Schisistomiasis 4
2.1.0 Intestinal Schistosomiasis 4
2.1.1 Acute Symptoms 4
2.1.2 Chronic Symptoms Intestinal Schistosomiasis 5
2.2.0 Urinary Schistosomiasis 6
2.2.1 Acute Symptoms of Urinary Schistosomiasis 7
2.2.2 Chronic Symptoms of Urinary Schistosomiasis 7
Chapter Three 10
Control of Schistosomiasis 10
Schistosomiasis is caused by infectious trematode worms of the genus Schistosoma. There are five schistosome species known to infect humans: S. haematobium, S. japonicum, S. mansoni, S. intercalatum, and S. mekongi (WHO, 2013). In 2011, an estimated 243 million people in 78 countries were living in areas of high risk for the disease (Barry, Simon, Mistry & Hotez, 2013). The African region is the most affected, with 42 countries endemic for the infection, followed by the Eastern Mediterranean region with 16 countries affected. Schistosomiasis was also endemic in 10 countries in the region of the Americas, six in the Western Pacific regions, and three in the Southeast Asian region and in Turkey, the only country affected in the European region The disability-adjusted life years (DALYs) lost as a result of schistosomiasis was estimated to be 1.7 million (Mathers, Ezzati& Lopez, 2007; WHO, 2014). However, in estimating the DALYs, the case definition used for schistosomiasis was limited to infection and associated mortality from schistosomiasis, and excludes mortality from bladder cancer, cirrhosis, or colon cancer that may be related to the infection. Hence, only an average of 0.006 disability weights was used in the estimation (Mathers et al., 2007). King re-estimated the DALYs associated with Schistosoma infection using the assumption that all past and present Schistosoma infections are part of the ongoing disease burden of schistosomiasis. Using a disability weight of 2%, the new DALYs estimate was 24–29 million, which was almost 20 times higher than the previous estimate (King, 2010).
Symptoms of schistosomiasis are caused by the body’s reaction to the worms' eggs. Intestinal schistosomiasis can result in abdominal pain, diarrhoea, and blood in the stool. Liver enlargement is common in advanced cases, and is frequently associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels. In such cases there may also be enlargement of the spleen.
The classic sign of urogenital schistosomiasis is haematuria (blood in urine). Fibrosis of the bladder and ureter, and kidney damage are sometimes diagnosed in advanced cases. Bladder cancer is another possible complication in the later stages. In women, urogenital schistosomiasis may present with genital lesions, vaginal bleeding, pain during sexual intercourse, and nodules in the vulva. In men, urogenital schistosomiasis can induce pathology of the seminal vesicles, prostate, and other organs. This disease may also have other long-term irreversible consequences, including infertility (Maguire, 2010).
The economic and health effects of schistosomiasis are considerable and the disease disables more than it kills. In children, schistosomiasis can cause anaemia, stunting and a reduced ability to learn, although the effects are usually reversible with treatment. Chronic schistosomiasis may affect people’s ability to work and in some cases can result in death. The number of deaths due to schistosomiasis is difficult to estimate because of hidden pathologies such as liver and kidney failure, bladder cancer and ectopic pregnancies due to female genital schistosomiasis.
The death estimates due to schistosomiasis need to be re-assessed, as it varies between 24 072 (1) and 200 000 (2) globally per year. In 2000, WHO estimated the annual death rate at 200 000 globally. This should have decreased considerably due to the impact of a scale-up in large-scale preventive chemotherapy campaigns over the past decade (Hams, 2013).
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