CHAPTER ONE

INTRODUCTION

1.1 Background Information

Intestinal schistosomiasis, also known as bilharziasis or snail fever, is primarily a tropical parasitic disease caused by eggs of adult stages of the blood fluke known as Schistosoma. The name bilharziasis was coined from the name of Theodor Bilharz, a German pathologist, who first identified the worms in 1851 (Nawal, 2010; WHO, 2010a).

Intestinal schistosomiasis is the second most prevalent tropical parasitic disease next to malaria, and is a leading cause of morbidity in endemic areas of Africa, Asia and South America (WHO, 1995). In some parts of Africa, the onset of haematuria due to urinary intestinal schistosomiasis is very common in adolescent boys, and due to lack of knowledge, it is seen as a normal phenomenon in some communities (Deswitz, 1981). It is estimated that over one third of the world’s population, mainly those individuals living in the tropics and sub-tropics, are infected by parasitic worms (Schall et al.,1993).

The disease is said to be responsible for the annual loss of between 1.7 and 4.5 million disability adjusted life years (DALYs), but recent meta-analysis challenges these burden estimates; they could be several-fold higher (Chitsulo et al., 2000). Most of the burden of intestinal schistosomiasis is concentrated in sub-saharan Africa with the highest prevalence and intensities usually found in school-age children, adolescent and young adults (Jordan et al., 1993). Intestinal schistosomiasis has a negative impact on school performance of the pupils and the debilitation caused by untreated infections undermines social and economic development in heavily affected areas (Huang and Manderson, 1992).

After more than 20 years of intestinal schistosomiasis control programmes, chemotherapy has been shown to be a very important tool. Nevertheless, in medium and long term infections, good sanitary habits, good water supply, proper sewage drainage and health education seem to be the real tool in definitive intestinal schistosomiasis control (Katz et al., 1998).Several environmental and socio-economic factors have been identified to be responsible for the continued persistence of intestinal parasitic infection in children. Some of these factors include poor sanitary conditions, unhygienic practices, lack of potable water, poor housing and poverty

(WHO 1991, Edungbola and Obi 1992; Savioli et al., 2003; Amuta et al., 2004).Recent global estimate have indicated than more than a quarter of the world’s populations are infected with one or more of the most common parasites; Ascaris lumbricoides, hookworm and Trichuris trichuira (Nawal 2010; WHO 2010a).

Helminth infections are more prevalent among school-aged children (Bundy and Medley, 1992). Maximum prevalence and intensities for Ascaris lumbricoides and Trichuris trichiura are achieved in children from 5-15 years of age while hookworm and schistosome infections are usually at their peak in late childhood to early adulthood (Bundy and Medley, 1992).

Five species of schistosomes are pathogenic parasites of humans. Out of which Schistosoma mansoni and Schistosoma haematobium are the most common worms while Schistosoma japonicum, Schistosoma mekongi and Schistosoma intercalatum have a more limited distribution. Other species, such as Schistosoma matheei and Schistosoma bovis are occasional parasites of human and Schistosoma incognitum may also prove infective to humans. The disease caused by schistosomes, intestinal schistosomiasis (=bilharziasis), is the most important disease of helminth origin and causes untold misery in about 75 countries (WHO, 1985). About 200 million people are said to be infected and 500-600 million people are exposed to the infection (Webbe, 1981). The Center for Disease Control and Prevention estimates that 150 to 200 million persons throughout the world are afflicted with intestinal schistosomiasis (CDC, 2010).

Control of intestinal schistosomiasis depends basically on the control of the snail vectors, a problem which presents an extremely complex ecological situation, and one which has been reviewed in a number of major publications (Jordan et al., 1993; WHO, 1985; Nmorsi et al., 2005; John et al., 2008). Snails of the family planorbidae serve as intermediate hosts of Schistosoma mansoni and Schistosoma haematobium. Schistosoma mansoni is transmitted by snails of the genus Biomphalaria and S. haematobium by Bulinus species (Chandiwana, 1986; King et al., 1988).

Salinity, temperature, velocity of the water and presence of aquatic vegetation support the snail colonies of the various genera. Snail population in any water reservoir starts to build up at the onset of the rainy season around May, they become abundant between October and

December (Shurrock, 2001; Nmorsi et al., 2005).

1.2 Statement of Research Problem

Intestinal schistosomiasis currently infects 200 million people in 74 endemic countries (WHO, 2010a). It affects primarily women and school – aged children. Infections occur when a person comes into contact with freshwater that is infested with schistosome cercariae and containing snail intermediate hosts. The infection can lead to stunted growth and development and in severe cases of bladder cancer and kidney, liver and spleen malfunctions (Kabatereine et al., 2004). Intestinal schistosomiasis 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 intestinal schistosomiasis live in Africa (Habib et al., 2000).

Intestinal schistosomiasis infection is associated with rural agricultural and other human activities around the freshwater bodies such as swimming, fishing, washing and bathing in ponds, rivers and dams, where the snail intermediate hosts breed. Construction of earthered dams to facilitate the breeding/ ground for snails. Children are more prone to

intestinal schistosomiasis infection due to their exposure to water bodies, through fishing, swimming, washing and fetching water for household chores. These activities expose these children to the infective stage of the parasite from the intermediate hosts in these water bodies. Personal hygiene, attitude and play habits make children especially vulnerable to infection (John et al., 2008). Women doing domestic chores, such as washing of clothes in infested water, are also at risk. Urogenital intestinal schistosomiasis is also considered to be a risk factor for HIV infection, especially in women. Approximately 10 million women in Africa have intestinal schistosomiasis during pregnancy (Mohammed et al., 2007; John et al., 2008).

The economic and health effects of intestinal schistosomiasis are considerable. In children, schistosomiaisis can cause anaemia, stunting and a reduced ability to learn, although the effects are usually reversible with treatment. Chronic intestinal 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 intestinal schistosomiasis (WHO, 2010a).

1.3 Justification

Several investigations have been conducted on the prevalence of intestinal schistosomiasis and other helminths in humans in several localities in Nigeria. To the best of our knowledge, no such investigation/research has been conducted in Jaba Local Government Area. There are a lot of water bodies in the area where children often go for fishing and swimming and can come in contact with the infective stage of the parasite. Children are at risk of the disease due to close proximity of irrigation farms and large dam reservoirs to their homes and their personal behaviours. It is with this background that the present study was designed.

1.4 Aim

To investigate the prevalence of urinary schistosomiasis and its co-infection with salmonella species among pupils in Jaba Local Government Area, Kaduna State.

1.5 Objectives

The study was therefore designed with the following objectives to:

i. determine the prevalence and intensity of intestinal schistosomiasis among primary school pupils in Jaba Local Government Area, Kaduna State.

ii. determine the age and sex specific prevalence of intestinal schistosomiasis infection in Jaba Local Government Area, Kaduna State.

iii. determine the risk factors associated with the transmission of intestinal schistosomiasis to primary school pupils in Jaba Local Government Area, Kaduna State.

iv. identify the potential snail intermediate hosts in water bodies

in the area.

1.6 Hypotheses

i. Intestinal schistosomiasis is not prevalent among primary school pupils in Jaba Local Government Area.

ii. The age and sex of primary school pupils are not associated with the prevalence of intestinal schistosomiasis in the study area.

iii. There is no specific risk factor associated with the transmission of intestinal schistosomiasis to primary school pupils in Jaba Local Government Area,Kaduna State.

iv. The snails are not vectors of intestinal schistosomiasis in the study area.