Risk Factors And Spatial Patterns Of Schistosoma Haematobium Infection Among Children

Risk Factors And Spatial Patterns Of  Schistosoma Haematobium Infection Among School Children In Town School Primary School, In Nkanu East L.G.A


This cross-sectional survey was conducted to precisely determine the prevalence of schistosomiasis due to Schistosoma haematobium in Town School Primary School, Umunevo, Amagueze in Nkanu East Local Government Area of Enugu State. Out of 45 urine samples collected in Town School Primary School, Umunevo, 25 (55.6%) were found to be  infected. More males than females were infected. Children  in 9-12 age group recorded the highest prevalence of (80%). Recommendations are made on its ways of reducing urinary schistosomiasis infecting school children in this region.



Schistosomiasis also known as Bilharziasis is a disease caused by blood flukes (trematodes) of the genus Schistosoma. It remains an important public health problem globally with an estimated 200 million cases reported each year (Engels et al, 2002). There are two types of schistosomasis, namely: Urinary Schitstosomiasis caused by Schistosoma haematobium and the Intestinal Schistosomiasis caused by four different dioecious species which are: Schitstosoma manoni, S. mekongi, S. intercalatum and S. Japonicum (Wiset, 1996).

Urinary Schistosomiasis is one of the threatening parasite disease of man (Hagan et al, 2001). The danger it pose the population in endemic area is growing. This is because increased water and energy requirement have led to the development of new breeding places for the snail host (e.g irrigation, projects, dams), for instance, the Volta dam lake in Ghana and Aswan dam lake in Egypt (Hagan et  al ,2005).

People are infected by contact with infested water during their normal daily activities for personal or domestic purposes, such as hygiene and recreation (swimming), or in professional activities such as fishing, rice cultivation, irrigation etc (Kabatereine et al, 2004).


The objectives of this study were:

  1. To determine the prevalence of Schistosomiasis among school children in Town School Primary School, Amagunze
  2. To know the risk factors associated with the infection.
  3. Finally, to educate the school children on how to avoid being infected with the disease.


          Schistosomiasis is the second most socio economically devastating parasitic disease after malaria (The Carter Center, 2008). This disease is most commonly found in Asia, Africa, and South America, in areas where the water contains numerous freshwater snails, which are intermediate host of the parasite. About 85% of the cases reported annually occur in sub-Saharan Africa and over 150,000 deaths are attributable to chronic infection with S. haematobium in this region (Southgate et al, 2005), (Vander et al, 2003). The disease affects many people in developing countries, particularly children who may acquire the disease by swimming or playing in cercariae infested waters (The Carter Center, 2008).

Schistosomiasis, also called Bilharziasis, was named after Theodor Bilharz, who first described the cause of urinary Schistosomiasis in 1851. The first doctor who described the entire cycle was Piraja Da Silva in 1908.  Urinary Schistosomiasis was first discovered in soldiers of Napoleon stationed in Egypt between 1779 and 1891 who suffered servere  haematuria.

In Nigeria, urinary Schistosomiasis is known to have existed from time immemorial and might have brought to the country by the migrating Fulani people when they traveled westwards from the Nile Basin (Cowper,1992). The earliest record of urinary Schistosomiasis in Nigeria is that of a  German  explorer who, in 1881, published the occurrence of endemic  haematuria in Bonny province (Akufongwe et al, 1996).

According to the World Health Organization (WHO), Nigeria is one of the countries most seriously affected by urinary Schistosomiasis and the disease of hyperendemic over large areas (WHO, 2001)

1.1.1            EPIDEMIOLOGY

The disease is found in tropical countries in Africa, the Caribbean, Eastern South America, South East Asia and in the Middle East. Schistosoma mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematabium in Africa and the Middle East, and S. japonicum in the far East. S. Mekongi  and S. interculatum are found locally in south east Asia and Central West Africa, respectively.

Schistosomiasis is endemic in 74-76 developing countries, infecting more than 200 million people, half of who  live in rural agricultural and peri-urban areas of Africa and more than 600 million people are at risk (Oliveira et al, 2004), (Carter Center 2008).

Of the infected patients, 20milion suffered severe consequences from the disease, and 120 million are symptomatic. Some estimate show that approximately 20, 000 deaths related to Schistosomiasis occur yearly. In many areas  Schistosomiasis infects a large proportion of children under 14 years of age (satayathum et al, 2006). An estimated 600 million people world wide are at risk from the disease (Engels et al, 2003).

A few countries have eradicated the disease, and many more are working towards it. The World Health Organization is promoting these efforts. In some cases, urbanization, pollution, and /or consequent destruction of snail habitat has reduced exposure, with a subsequent decrease in new infectious. The most common way of contacting Schistosomiasis in developing countries is by wading or swimming in lakes, ponds and other bodies of water that are infested  with the intermediate host snails (usually of the Biomphalaria, Bulinus, or Oncomelania genus). (De Cassia et al, 2007).

1.1.2            PATHOLOGY

          The eggs of S. haematobium provoke granulomatous inflammation, ulceration, and pseudopolyposis of vesicle and urethral walls. Adult are found in the venous  plexuses around the urinary bladder and the released eggs transverse the wall of the bladder causing haematuria and fibrosis of the bladder. The bladder becomes calcified, and there is increased pressure on ureters and otherwise known as hydronephrosis. Kidney failure deaths due to urinary tract scarring, deformity of ureters and the bladder caused by S. heamatobium infection have become less common due to modem drugs, (Gryseels et al, 2006), (King et al, 2002). Inflammation of the genitals due to S. haematobium may contribute to the propagation of HIV (Leutscher et al, 2005). Studies have also shown the relationship between S. haematobium infection and the development of squamous cell carcinoma of the bladder (Khurana et al, 2005).

Schistosomiasis can be divided into three phases:

  1. The migratory phase lasting from penetration to maturity
  2. The acute phase which occurs when the schistosomes begin producing eggs,
  3. The chronic phase which occurs mainly in endemic areas (Black, 2005).

1.1.3            LIFE CYCLE

The free swimming, infective larval cercariae penetrates the human skin when exposed to contaminated  water. The cercariae enter the blood stream of the host where they travel to the liver to mature into adult  flukes. In order to avoid detection by the immune system of the host, the adult worm have the ability to coat themselves with host antigen (Black, 2005). After a period of about three weeks the young flukes migrate to the bladder to copulate. The female fluke lays as many as 3,000 eggs per day eggs which migrate to the lumen of the urinary bladder and ureters. The eggs are eliminated from the host into the water supply with micturition. In fresh water, the eggs hatch forming free swimming miracidia which penetrate into the intermediate snail host, Bulinus Species (Black, 2005). Inside the snail, the miracidium sheds

its epithelium and develops into a mother sporocysts. After two weeks daughter sporocysts are formed. Four weeks after the initial penetration of the miracidium into the snail, furcocercous cercariae (infective stage) being to emerge from the snail. The cercariae cycle from the top of the water to the bottom for three days in the search for a human host. Within half an hour the cercariae enter the host epithelium (Roberts and Janovy, 1996).

1.1.4            SIGNS AND SYMPTOMS

Schistosomiasis is a chronic disease and infections are subclinically symptomatic, with mild anaemia being common in endemic areas.

The first symptom of the disease is an intense initiation and skin rash (dermatitis) formally called swimmers’ itch, which occurs within 24hours of the infection at the site of cercarial penetration as a result of hypersensitvity reaction (James, et al, 2006). After an incubation period of about 4-6 weeks, there is fever (Katayama fever) with general weakness and prostration which are often mistaken for that of malaria, followed by cough and pulmonary reactions as the parasites migrate through the lungs (Dalton et al, 2004). As the worm grows to maturity in the hepatic portal veins, the patient may complain of loss of appetite and weight.

Intestinal symptoms include abdominal pain and diarrhea (which may be bloody).

Urinary symptoms many include frequent urination, painful urination (dysuria), and blood in the urine (haematuria). Haematuria is the most characteristic sign of urinary schistosomiasis

Other symptoms of schistosomiasis may include slight hepatitis, hypertension, hepatosplenomegaly, Eosinophilia and Genital sores.

1.1.5            DIAGNOSIS

The presence of microhaematuria is detected using combi-9-strip, a reagent strip which can also be used to detect the presence of protienuria. Detection of blood and protein in the urine sample is just a subjective of the disease and is not confirmatory. A confirmatory diagnosis of the disease is by detecting a terminal spine ova in the urine sample of the patient (Cheesbrough, 1999). This diagnosis method is most commonly carried out owing to its simplicity and low cost. The eggs are rarely found in faeces.

Other diagnostic methods of the disease include x-rays examination of the bladder wall for calcified eggs, ultrasonograph and serological tests (complement fixation test), Betonite Flocculation Test and Interadermal Skin Test using antigen prepared from cercariae and adult worms. A rapid diagnostic antibody test in the form of dipstick has also been developed and it is in current use in Egypt (El-khoby et al, 1998). This diagnostic method above is not in use in this part of the world owing to their high cost and unavailability. An immunodiagnostic assay for Schistosoma haematobium infection is based on two systems. One is based on the detection of antibodies produced by the hosts’ immune response to the specific adult worm-microsoma antigen using the Falcon Assay Screening Test (FAST), Enzyme Linked Immunoabsorbent Assay (ELISA) and Enzyme Linked Immune-electro Transfer Blot (ELTB). The other is based on the detection of circulation of schistosomal antigen using monoclonal antibodies. The soluble genus of specific adult worm antigens include Circulative Anodic Antigen (CAA) and the Circulatory Soluble Egg Antigen (CSEA) (Parija, 1998).

Al-shebing et al, (1999) showed that sensitivity of detecting  Schistosoma haematobium, circulatory antigens and antibodies improved significantly, when a combination of urine CCA and serum CAA were used for detecting circulation of antibodies against Schistosoma haematobium  adult worm –microsomal antigen. Detection of soluble antigen will not only quantify the parasite load but will also detect recent infections.



          Preventing is best accomplished by eliminating the water-dwelling snails that are the natural reservoir of the disease. Acrolein, Copper Sulphate, and Niclosamide   can be used for this purpose. Recent studies have suggested that snail population can be controlled by the introduction of, or angementation of exiting, crayfish populations, as with all ecological interventions, however, this technique must be approached with caution.

In 1989, Aklilu Lemma and Legesse Wolde Yohannes received the Right Livelihood Award for their research on the use to sarcoca plant to control the snails. Concurrently, Dr chidzeve of Zimbabwe researched the similar Gopo berry  during the 1980s and found that it could be used in the control of infected freshwater snails. In 1981, he drew attention to his concerns that big chemical companies denigrated the Gopo Berry alternative for snail control. Reputedly Gopo Berries from hotter Ethiopia climates yield the best results. Later, further studies were conducted between 1993 and 1995 by the Danish Research Network for international health, and the results was the same with the Gopo Berries (Molgaard et al, 2000).


For many years from the 1950s onwards, civil engineers built vast dams and irrigation schemes, oblivious to the fact that they would cause a massive rise in water-borne infections like schistosomiasis. The detailed specifications laid out in various UN documents since the 1950s could have minimized this problem.

Irrigation schemes can be designed to make it hard for the snails to colonize the water, and to reduce the contact with the local population (Charnock, 2000). Bridges should also be constructed in endemic areas where mostly their source of water supplies  are streams, rivers and ponds


          Education of the populace (mainly those in endemic areas) on the need for proper sanitary condition and hygiene is of paramount important in the prevention and control of urinary  schistosomiasis. They should also be educated on the importance of seeking proper medical attention early, more especially when they experience blood urine and pains during urination.

          Defeacation or urination in or near open water or stream should be avoided so that snails will have less chance of becoming infected. There is also need to make use of protective covering like rubber boots if there is any need to enter an infected water. In Bao-uniao,in Brazil, the use of rubber boots during field work has been shown to reduce the transmission of urinary schistosomiasis by preventing contact with cercariae- infected water  (Gazzinelli et al, 1997).    

1.1.7            TREATMENT

Schistosomiasis is readily treated using a single oral dose of the drug praziquantel annually (The Carter Centre, 2008). As with other major parasitic diseases, there is ongoing and extensive research into developing a schistosomiasis vaccine that will prevent the parasite from completing its life cycle in humans.

The World Health Organization has developed guidelines for community treatments of schistosomiasis based on the estimate intensity of infection among children in endemic villages (WHO, 2006).

When a village reports more than  50 percent of children having blood in their urine, everyone in the village receives treatment (WHO, 2006).

When 20 to 50 percent of children have bloody urine, only school-age children are treated (WHO, 2006).

When less than 20 percent of children have symptoms, mass treatment is not implemented at all (WHO, 2006).

The Bill & Melinda Gates foundation has recently funded an operational research program-the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) to answer strategic questions about the way forward in schistosomiasis control and elimination. The focus of SCORE is on development of tools and evaluation of strategies for use in mass drug and administration campaigns.

Antimony has been used in the past to treat the disease. In low doses, this toxic mettalloid bonds to sulfur atoms in enzymes used by the parasite and kills it without harming the host. This treatment is not referred to in present day peer- review scholarship; praziquantel is universally used. Outside of the U.S, there is a second drug available for treating Schistosoma mansoni (exclusively) called Oxaminique.

Mirazid, an Egyptian drug, was under investigation for oral treatment of the disease up untill 2005. The efficacy of Praziquantel was proven to be about 8 times that of Mirazid and therefore it was not recommended as a suitable agent to control Schistosomiasis (king et al, 2002).

Experiments have shown that medicinal castor oil is an oral-penetration agent to prevent Schistosomiasis and that praziquantel effectiveness depended upon the vehicle used to administer the drug (e.g., cremophor/castor oil) (salafsky et al, 1999).