STUDIES ON RICE FIELDS SNAILS AND URINARY SCHISTOSOMIASIS AMONG RICE FARMERS IN KURA LOCAL GOVERNMENT AREA, KANO STATE, NIGERIA
Objectives of the study
- Species composition, abundance and distribution of snail species in rice fields in Kura Local Government
- The rate of cerceriae infection in snail species in rice fields in Kura Local Government
- Physicochemical parameters of rice fields water in relation to snail occurrence in Kura Local Government
- Distribution, prevalence and intensity of urinary schistosomiasis among rice farmers in some districts in Kura Local Government.
History of Urinary Schistosomiasis
Schistosomiasis, caused by a trematode helminth, is present in different parts of the world and variously distributed. The causative agent has however only relatively been identified but the symptoms of the disease have been recognised a very long time ago. The most obvious sign of urinary schistosomiasis is blood in urine. This attracted the attention of ancient Egyptians who described the disease as „a-a-a‟ disease (Okpala,2010). Schistosoma haematobium was the first to be described by a German Pathologist, Theodore Maximilian Bilharz in 1851 during an autopsy on an Egyptian patient and the popular name for all forms of schistosomiasis is „bilharziasis‟ in honour of his discovery. Until 1906 it was assumed that Schistosoma mansoni was represented by the two species Schistosoma haematobium and Schistosoma japonicum. It had however been noted by Sir Patrick Manson, a physician to the Seamen‟s Hospital in Greenwich that the eggs passed in the urine from schistosomiasis patients were all terminally spined while only those found in the faeces had the lateral spines (Okpala, 2010). He then speculated that possibly there are two species of bilharzia, one with lateral spined ova depositing its eggs in the rectum only, the other haunting the rectum and bladder differently. The presence of the two types of spined eggs, and of two clinical forms of the disease, the vesical and the intestinal, caused considerable confusion until Sambon, in 1907 demonstrated the existence of two species, Schistosoma haematobium and Schistosoma mansoni. He named the worm that produced eggs with lateral spineSchistosoma mansoni. The observations of Sambon and others were confirmed by the experimental work of Leiper in 1915 and later by other investigators (Okpala, 2010). Concurrently with the work carried out by Bilharz in Egypt, other scientists and physicians were also becoming aware of this disease, particularly in Japan where in 1847, four years before Bilharz described his new trematode, Yoshinao Fujii, a physician working in Numakuma County, reported the occurrence of Schistosoma japonicum in district of Kawanami (Okpala,2010). He also noted that the disease was most severe in Katayama district but was also found in other several nearby areas notably Ikariyama District and that it was called „Katayama‟ disease. So the first description of Oriental schistosomiasis or „katayama‟ disease was made by Fujii 1847. Between 1890 and 1904 Yamagiwa, Kurimoto and Fujinami found the eggs in various organs of human beings at autopsy, and Fujinami 1904 found the eggs in the faeces of patients afflicted with „katayama‟ disease (Okpala, 2010).
Schistosomiasis is common worldwide, causing 56% of known cases of calcifications in the bladder known as bladder stone, calcified eggs of schistosomes have been found in Egyptian mummies dating from 1200 to 1000 BC (Usaini et al., 2015 ).The distribution of schistosomes in man is governed by the existence of suitable intermediate molluscan host. Schistosomiasis is a water-borne parasitic disease thataffects 200 million people and more than 750 millionpeople are at risk (Steinmann et al., 2006).The World Health Organization (Bolaji et al., 2015) considers it as a significant public health problem inmuch of Africa. WHO estimates that worldwide, 180 million people live in endemic areas and 90 million are infected with the parasites. Most of these live in Sub-Saharan Africa. About 70 million persons suffer from terminal haematuria, 18 million from associated bladder wall pathology, and 10 million from hydronephrosis (an accumulation of urine in the kidney due to obstruction of the ureter). It is also estimated that
150,000 people die each year from resultant renal failure and an unknown but significant number from bladder and other genitourinary cancers. The overall mortality rate is estimated to be at least2 per 1,000 infected patients per year (Bolaji et al., 2015).In many places,there is a higher incidence of infection in young boys and women. This occurs because of increased contact with water compared to other population groups in cultures where women typically fetch water for household use and young boys often play in or near water.In some regions where men are primarily freshwater fishermen or farmers using irrigation farming, they have higher rates of schistosomiasis. These differential rates of transmission depend on cultural practices. It is important to consider them when planning treatment, prevention, and control strategies (Bolaji et al., 2014).
Schistosoma haematobium co-exists with Schistosoma mansoni and the distribution of the two species is somewhat confusing. Schistosoma haematobium is highly endemic in the Nile Valley, present from Morocco to Egypt on the Mediterranean Coast, in Ethiopia and in the Sudan where it co-exists with Schistosoma mansoni. In West Africa, it is more widely disseminated than Schistosoma mansoni, occurring in Senegal, Guinea, Sierra-Leone, Liberia, Ghana, Nigeria, Chad, the Central African Republic, the Congo Republic, Gabon and Angola; also widely distributed in the countries in East Africa, including Madagascar and the Islands of Mauritius (Okpala, 2010). Schistosoma mansoni is prevalent in the Nile Delta in Egypt, in Sudan, Ethiopia, Libya, Central Africa and East Africa. In West Africa, it is present in Nigeria, Ghana, the Cameroon, Chad, Central African Republic, the Congo and Gabon. It is found in Venezuala, the Guianas, Eastern Brazil, Dominican Republic and Puerto Rico. The distribution of Schistosoma japonicum is confined to the Far East- Formosa, Celebes and several Islands of Philippines (Okpala, 2010).
The pattern of distribution of schistosomiasis is changing in two opposite directions: the increase of irrigation systems favours its spread and control schemes block its transmission. Water development projects in Africa are essential but often associated with an increase in water-borne diseases such as schistosomiasis. New fresh-water habitats for snail intermediate hosts of schistosomes may be created by construction of dams and irrigation projects. Greater opportunities for water contact lead to increase of both urinary and intestinal schistosomiasis as has been observed in villages along the shores of the Volta (Ghana), Kariba (Zimbabwe), Kainji (Nigeria) and Nasser (Egypt and Sudan) lakes.Humans are the major reservoirs of human schistosomes causing schistosomiasis. Apart from the role of humans as the major reservoirs of infection, other mammals have been incriminated as not less than 38 mammals have been found to be naturally infected by S. mansoni. A review of the situation in Brazil showed that at least 15 specimens of mammals, mostly rodents, werenaturally infected by S. mansoni. Since 1962, natural S. mansoni infections have been found in cattle in Brazil, Sudan and Venezuela. Although experimental infections with S. haematobium have been achieved in large primates and most recently in hamsters, there is no evidence of natural infection in other mammals (Okpala, 2010).
Distribution of Schistosomiasis
Schistosomiasis is widely distributed in the world.The areas affected are the Americas (Brazil, Venezuela and Suriname aswell as several Caribbean Islands),the Eastern Mediterranean (Islamic Republic of Iran, Iraq, Saudi Arabia, Syrian Arab Republic and Yemen), Eastern Asia (Cambodia, China, Indonesia, Japan, People‟s Democratic Republic of China, the Philippines) and some parts of Africa. (Ying- Si Lai et al., 2015) literature search identified Schistosoma haematobium and Schistosoma mansonisurveys done in, respectively, 9318 and 9140 unique locations. Infection risk decreased from 2000 onwards, yet estimates suggest that 163 million to 172 million (95% Bayesian credible interval, 155 million to 172 million; 18.5%, 17.6-19.5) of the sub-Saharan African population was infected in 2012. Mozambique had the highest prevalence of schistosomiasis in school-aged children (52.8%, 95% credible interval 48.7-57.8). Low-risk countries (prevalence among school-aged children lower than 10%) included Burundi, Equatorial Guinea, Eritea and Rwanda (Ying- Si Lai et al., 2015). Like many other parasitic helminths, the distribution and intensity of schistosome infections are variable by locality. This is particularly true with this parasite, mainly due to the strictly limited ecological conditions for habitats of vector snails and conditions of habitats inrelation to annual rainfalls, unexpected drought, irrigation projects and industrial activities (Okpala, 2010). Schistosoma haematobium is found in 53 countries in the Middle East and Africa, including the Island of Madagascar and Mauritius (Okpala, 2010). There is also an ill-defined focus of S. haematobium in India (Okpala, 2010). Intestinal schistosomiasis occurs in 45 countries including the Arabian Peninsula, Egypt, Sudan, Sub-Saharan Africa, Brazil, some Caribbean Islands, Suriname and Venezuela.The global distribution of schistosomiasis has changed significantly in the past 50 years, with control successes achieved in Asia, the Americas, North Africa and Middle East. Schistosomiasis has been eradicated from Japan, transmission has been stopped in Tunisia and very low in Morocco, the Philippines, Saudi Arabia and Venezuela (Okpala, 2010).
Human schistosomiasis is the most prevalent of the water borne diseases, with a very great risk tothe health of rural populations (Biu et al.,2009). Schistosomiasis is common worldwide, causing 56% of known cases of calcifications in the bladder known as bladder stone. The disease affects more than 200 million people worldwide (8% of the world population) and as many as 500-600 million people have been exposed to schistosomiasis of all kinds, being more common in Africa, Asia and South America (Robert and Cirillo, 2002).
However, environmental changes linked to water resources development, increasing population and population migrations has led to the introduction and spread of the disease to previously low or non-endemic areas, particularly sub-Saharan Africa (Okpala, 2010). It is well documented that the construction of man-made lakes in areas endemic for schistosomiasis frequently leads to increase in level of this disease in the human population. Development of water resources and their management can increase schistosomiasis transmission (Duwa and Oyeyi, 2009).An analysis, based on African studies, showed that there is a risk ratio of 2.4 and 2.6 for urinary schistosomiasis (caused by S. hematobium) and intestinal schistosomiasis (caused by S.mansoni) respectively, among persons living adjacent to dam reservoir (Duwa and Oyeyi, 2009).Bilhariziasis is one of the most important diseases and is evident in about 75% of tropical developing countries, schools and residents in rural and irrigated Agricultural areas are estimated to be infected while between 500 and 600 million people are at risk (Usaini et al., 2015). Over 200 million people are currently estimated to be infected.
There are a number of less important species of schistosomes infecting man. Schistosoma intercalatum is endemic in parts of Zaire, Gabon, Cameroon, with small foci in Central African Republic, Chad, Nigeria and Burkina Faso (Okpala, 2010). Schistosoma malayensis was recently reported in Malaysia. In addition, a number of animal species accidentally infect man to cause zoonotic infections. These include S. bovis infecting cattle, sheep and goats in Africa, parts of Southern Europe and Middle East; S. matthei infecting cattle, sheep and goats in Central and Southern Africa; S. margrebowiei infecting antelope, buffalo and water buck in Southern and Central Africa; S. curassoni infecting domestic ruminants in West Africa and S. rodhaini infecting rodents and carnivores in parts of Africa (Okpala, 2010).
Schistosomiasis in Nigeria
In Nigeria, both urinary and intestinal schistosomiasis caused by S. haematobium and S.mansoni, respectively are prevalent (Bolaji et al., 2015). Students are often vulnerable to infection, presenting clinical symptom like haematuria, suprapubic pain, dysuria, obstructive uropathy, kidney failure and elevated risk of bladder cancer. The mortality rate due to non-functioning kidney and haematemesis from S. haematobium has been estimated and it was over 150,000 per year, thus indicating that urinary schistosomiasis has become a grave public health problem in sub-Saharan African and second to malaria in term of morbidity and mortality (Bolaji et al., 2015). Until recently, schistosomiasis was not considered a public health problem in Nigeria for two reasons. Firstly, schistosomiasis was restricted to rural communities where hygiene is inadequate, where poverty prevails, where malnutrition and infection with other parasites are common (Okpala, 2010).
Secondly, it is a disease common to school aged children in whom the disease remains silent or mildly asymptomatic for many years. According to the legend Blair (1956), the Fulani tribe migrants of Northern Nigeria, transmitted schistosomiasis from the Upper Nile Basin. The disease, therefore has a long history in Nigeria. It is essentially an infection of rural agricultural communities where rural lifestyle and behaviour encourage the contamination of inland water with human excreta and urine. To this end, most previous studies on schistosomiasis in Nigeria were concentrated in rural areas (Arinola, 1995).The distribution of Schistosoma haematobium was described as being almost universal in the North, and patchy elsewhere. Schistosoma haematobium is probably endemic in the Northern Region, and some areas are marked particularly by heavy infection rates. These areas include Katsina, Kano, Zaria, Kaduna, Birnin Kebbi and Argungu. Infection of man by both S. mansoni and S. haematobium is wide-spread in two of the former regions of Nigeria – West and North, and less in the East. Other parts of the Northern region from which high or fairly high infection rates have been reported are Plateau area, Yola, Biu area, Maiduguri, Potiskum area, the Wulgo area of Lake Chad Basin, the Riverine area along the Niger from Wawa to Pategi and Bida. Akogun and Obadiah (1996) also reported that schistosomiasis is common in Nigeria and is especially associated withwater related activities. In its geographical distribution in Nigeria, urogenital schistosomiasis is regarded as a disease mainly of the semi and dry savannah region, especially areas where there are irrigation schemes (Akogun and Obadiah, 1996). In Nigeria, the earliest known report of high prevalence of haematuria relates to the dry North (Donges, 1967). There were some reports on the epidemiology in the city area of Ibadan (Akinkugbe, 1962) Investigations indicate that the disease may be increasing in prevalence and importance particularly in the remote poorly accessible rural communities (Okpala, 2010). Various studies have been carried out to show prevalence and intensity of schistosomiasis in various States; Niger – Benue basin of Kogi state a prevelance and intensity studies was carried, a total of 1,104 samples were collected and analyzed, 206 were infected with the parasite, overall geometric mean intensity of 118.2 eggs/10ml urine was recorded, prevalence of infection was significantly higher in males (19.4%) than in females (16.5%) but there was no significant difference (p > 0.05) in intensity of infection between the two sexes. In this study children of 10-14 years with prevalence of (22.7%) contributed more to the transmission of the disease in the Niger-Benue basin than those of age group > 20 years with prevalence (20.8%) (Ejima and Odaibo, 2010).
In another study on Schistosoma haematobium among school children in Ajase – Ipo, Kwara state, Nigeria out of 150 individuals investigated, 88 (58.7%) were found infected, which was slightly higher in males (62.0%) than females (54.9%) (Bolaji et al., 2015). Furthermore,in Sarkawa fishing community in Yauri, Kebbi State, urinary schistosomiasis was analyzed among 198 school age children out of which 90 pupils were positive forSchistosoma haematobium giving a prevalence of (45.45%) (Rikoto and Danladi, 2013). In another study in Ebonyi State, Nigeria, Ivoke et al. (2015) reported that 375 (46.18%) of 812 children in rural communities carried the infection.
Dams and irrigation projects which are wide-spread in Nigeria, electric power, water emanating from the water- flow creates suitable environment for snail breeding and industrial developments have contributed significantly to the spread of schistosomiasis. Ironically, these otherwise beneficial development activities favour increased transmission of water based diseases. Migrants, workers, and herdsmen, who represent a significant number of people in endemic areas, are both carriers and target for infection. Thus, schistosomiasis will be very much a concern for some time in Nigeria.
Schistosomiasis in KanoState
The distribution and intensity of schistosomiasis are variable by locality, mainly due to the strictly limited ecological conditions for the habitat of the vector snails and changing conditions of habitat in relation to annual rainfalls, unexpected drought, irrigation schemes and other water development projects (Okpala, 2010). A study was carried out in July 2005 to August 2007 on comprehensive mapping of urinary schistosomiasis using Geographic Information Systems (GIS) in Kano State, Nigeria to integrate the demographic, parasitologic and site location data of 132 towns / villages, in the 44 Local Government Areas of Kano State. A total of 6600 urine samples were examined for S. haematobiuminfection, 2820(42.7%) were positive out of the 44 Local Government Areas of Kano State and was presented in Table 2.1(Abdullahi et al.,2009).
- CONCLUSIONS AND RECOMMENDATIONS
- A total of 1959 specimens of five snail species including 39-crawshayi, 307- B. pfeifferi, 548- B. globosus, 95-L.natalensis and 970-M.maculata were obtained from rice field and four specimens of B globosus shedded cercariae, thus intermediate host of urinary schistosomiasis was present in the rice fields in Kura Local Government Area, Kano State, Nigeria.
- The snails occurred at pH (8.24-9.70), TDS (30-39ppm), EC (64-77µs/cm) and
- temperature (24-27.5 C) with no significant difference in species specific preference, therefore snails were found in alkaline aquatic rice fields habitat in Kura Local Government Area, Kano State, Nigeria.
- Overall urinary schistosomiasis prevalence of 50.24%; male and female prevalence of 75% and 43.24% (p < 0.05) respectively were obtained for rice farmers in all the four districts.Modal prevalence (78.04%) occurred in children 10yrs and younger. Intensity of infection ranged from light (77.25%) to heavy(18.0%).
- Efforts should be made to prevent transmission of schistosomiasis by adequately treating the infected rice farmers and control of the snail intermediate hosts in rice
- Policy makers should recognize the disease as a focal public health problem and should be willing to promote and support control where and when
- Health education should be intensified to create needed awareness on preventive measures amongst rice
Contribution to knowledge
- The overall prevalence of urinary schistosomiasis was 24%, with the prevalence among males being 52.75% while in femalesit was 43.24%.This revealed that there is high prevalence of urinary schistosomiasis and active transmission of schistosomiasis among the rice farmers in Kura Local Government Area, Kano State, Nigeria.
- This study revealed the presence of intermediate host of urinary schistosomiasis Bulinusglobosus, intestinal schistosomiasis; Biomphalaria pfeifferiandalsofascioliasis; Lymnaea natalensis in the study districts of Kura Local Government Area.
- Abdullahi, M.K., Bassey, S.E. and Oyeyi, T.I. (2009).A comprehensive mapping of urinary schistsomiasis using geographical information system in Kano State, Nigeria.Bayero Journal of Pure and Applied Sciences,2 (1): 41-46.
- Abubakar, S., Oyeyi, T.O., Yunusa, I. and Ahmed M.K. (2015).Co-infection of urinary schistosomiasis and haematuria.Annals of Experimental Biology, 3(1): 29-32.
- Adewunmi, C. O. (1984). Water extracts of Tatrapleura tetraptera as effective molluscicide for the control of schistosomiasis and fascioliasis in Nigeria. Journal of Animal Production Research,4(1): 73-84.
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- Ahmad, M.M., Getso, B.U. and Ahmad, U.A (2014).Water contact patterns and urinary schistosomiasis among school children in endemic area of Wudil, Kano, Nigeria. Journal of Pharmacy and Biological Sciences, 9:1-4.
- Akinkugbe, O. O. (1962). Urinary schistosomiasis in Ibadan school children.West African Medical Journal,11:124-127.
- Akogun, O. B. and Obadiah, S. (1996). History of haematuria among school aged children for rapid community diagnosis of urinary schistosomiasis. The Nigerian Journal of Parasitology,17: 11 – 15.
- Anosike, J.C, Nwoke, B.E.B and Njoku, A.J. (2001).The validity of haematuria in the community diagnosis of urinary schistosomiasis infection.Journal of Helminthology, 75(3): 223-225.
- Anosike, J.C, Oguwuike, U.T, Nwoke, B.E.B, Asor, J.E, Ikpeama, C.A and Nwosu, D.C. (2006).Studies on vesical schistosomiasis among rural Ezza farmers in the southwestern border of Ebonyi State, Nigeria.Annals of Agricultural and Environmental Medicine, 13:13-19.
- Arinola, O. G. (1995). Prevalence and severity of urinary schistosomiasis in Ibadan, Nigeria.
- East African Medical Journal,72:746-748.