Several studies on urogenital schistosomiasis among pre-school children, school-aged children, and adults have been conducted, yet little data exist about urogenital schistosomiasis in senior high school students. Often, findings on this category, where available, have been merged with other groups of school-aged children. This study showed a prevalence of 30.54 % (27.04─34.28 %) of urogenital schistosomiasis among senior high school students in the study area. Expectedly, due to the focal nature of the infection, this result is different from previous findings of 26.8 % in Ebonyi State, South East Nigeria, 52.8 % at the point -of- care in northeastern Zimbabwe, and 44.3 % in North Central Nigeria [17–19]. The differences observable among these prevalence rates might be linked to ecological factors, cultural practices, and water contact activities unique to our study population. This may require further investigation.
The mean intensity of infection was 30.27(17.97-42.57) eggs/10 ml of urine in this study. Previous records from Anambra State, South East Nigeria (10.1 eggs/ 10 ml of urine), Kaduna State, North West Nigeria (73.93 eggs/10 ml of urine) and the Republic of Chad (<13.5 eggs/10 ml of urine) further confirm the focal nature of urogenital schistosomiasis [20–22]. These differences might be as a result of seasonal variations, proximity of infested water bodies, natural tendency of subjects towards recreation (swimming and playing in shallow water), and the state of social amenities in both the study area and some states in Nigeria mentioned above.
A higher prevalence rate of urogenital schistosomiasis (28.37 %) and a higher mean intensity of infection (32.21eggs/ 10 ml of urine) were recorded among males. This conforms to the usual trend recorded previously [23–25] and could be explained by males having more frequent contact with water due to swimming, fishing, molding bricks from clay, and irrigation and construction work.
However, there are contrary reports from Ogun State, Nigeria (Males: 57.1 %, Females: 59.2 %) and Khartoum North, Sudan (Males: 22 %, Females: 34 %) where females suffered a higher prevalence rate of urogenital schistosomiasis [14, 26]. This might be explained by gender-sensitive cultural or religious beliefs unique to ethnic groups which predispose a particular gender to a higher infection rate in the aforementioned areas. For instance, in the northern part of Nigeria, school-aged males fetch water from open sources for sale in a bid to make ends meet.
Generally, the results of this survey reflected that the prevalence rate of urogenital schistosomiasis and associated infection intensity reduced sharply as age increases. This is in agreement with previous findings in Nigeria and Sudan [23, 26] and is possibly due to the cultural practice of according dignity to older children by exempting them from domestic activities that require contact with unwholesome water sources. Access to knowledge about the epidemiology of urogenital schistosomiasis through Health Science and Biology offered as subjects might also contribute to this. In addition, the older people get, the more possible it is to acquire knowledge about disease prevention and control. Conversely, previous studies from Senegal and Ethiopia have reported increases in prevalence of urogenital schistosomiasis as the age of the respondents increased [13, 27], which could possibly be explained by the children in these studies showing an increase in water contact activities as they grow older.
Moreover, the highest prevalence rates in this study were recorded in the age groups of 15─17 (16.28 %) and 18─20 (10.38 %) years. This implies, on a general note, that these adolescents engage in more water contact activities than the other age groups in this survey. It could be further deduced that they shoulder the responsibility of providing water for their homes. The lowest prevalence rate (0.16 %) and mean intensity of infection (3 eggs/10 ml of urine) was recorded in the 24─26 age group. However, the highest mean intensity (47 eggs/10 ml of urine) of infection was recorded in the age group 12─14 years, which is suggestive of more contact with streams, rivers, ponds and lakes while swimming and sourcing water for domestic needs.
In agreement with these findings, it was reported that the highest mean intensity of urogenital schistosomiasis was recorded in the age group of 10─14 years in Plateau State, North Central Nigeria and Ebonyi State, South East Nigeria [23, 28].
Other studies carried out in Plateau and Ogun States, Nigeria reported that the highest prevalence rates were observed in the age group of 15─19 years [25, 29]. Findings from Ebonyi State also reported that the age group above 24 years showed the lowest mean intensity of infection with urogenital schistosomiasis [28].
Also noteworthy is the fact that respondents were reliant on multiple sources of water for domestic consumption. Combined recreational activities of swimming and playing in shallow water [COR (95 % CI): 2.87 (2.03─4.07)] using dams, ponds, rivers and streams [COR (95 % CI): 6.89 (1.38─34.49)]; and using dams, ponds, rivers or streams [COR (95 % CI): 2.09 (1.59─2.76)] were significantly associated with urogenital schistosomiasis.
Respondents who relied on dams, ponds, rivers and streams had the highest frequency of infection (75 %), while those who combined swimming with playing in shallow water bodies recorded the second highest infection rate (55.56 %) and the highest mean intensity of infection (34.29 eggs/10 ml of urine). These are reflections of a high frequency of exposure of the respondents to infested open water bodies. However, a survey conducted in Malawi [30], found that play/bath in an open water body was not found to be associated with urogenital schistosomiasis infection [COR (95 % CI): 1.21 (0.35–4.10)]. This suggests that interactions among determinant factors play a significant role in the transmission of the disease.
Furthermore, this survey found that the second highest mean intensity of infection (32.83 eggs/10 ml of urine) was recorded among subjects who either played in shallow water or had a previous history of swimming. A survey carried out in Kaduna State indicated that users of pond water had the highest prevalence rate urogenital schistosomiasis [21], while in Northern Ghana and Blantyre, Malawi, contact with streams, wells, rivers, streams, dams, and springs was found to be associated with S. haematobium infection [30, 31]. It is pertinent to recall that the values of disease prevalence (30.31 %) and mean intensity of infection (31.39 eggs/10 ml of urine) obtained among users of bore-holes, taps, sachets and wells appear outrageously high, and there are different perspectives on this. One reason could be due to respondents largely utilizing open, infested water sources, although well water, has the highest tendency of being exposed to the environment compared to other closed water sources. On the other hand, it could be hypothesized that the wells in the study area were shallow and either completely uncovered or partially covered, thus enhancing interaction with S. haematobium egg-infested dust particles.
In addition, modern waste disposal facilities are limited and the terrain of the study area is dusty and rocky. Consequently, the soil is stony and it is usually very tasking to dig deep while constructing wells in the locality. Surveys conducted in Malawi and Dikwa, Borno State, North East Nigeria [30, 32], are not in agreement with these findings.
In this study, location was associated with urogenital schistosomiasis [COR (95 % CI): 1.63 (1.27─2.09)]. Respondents who lived in Dutsin-Ma were twice as likely to be infected [COR (95 % CI): 2.31 (1.76─3.03)] compared to those living in Safana. This is consistent with the knowledge that infection becomes prevalent in areas close to dams and the Dutsin-Ma LGA is home to the Zobe Dam, which provides water for irrigation, fishing, recreational activities, and domestic use. Previous studies from Sudan and Nigeria [10, 19] have reported the role location plays in the prevalence of the disease.
Altitude [COR (95 % CI): 1.59 (1.14─2.24)] was also found to be associated with infection. Respondents from a higher elevated area had a higher chance of becoming infected with the cercariae of S. haematobium probably because such elevations are prone to higher temperatures which favor the hatching of eggs laid by adults into miracidia larvae. Moreover, higher elevated areas easily accumulate water, which in turn harbor the snail intermediate host. Findings in Cross River State, Nigeria, reported a prevalence of 0 % for altitudes above 500 m [33]. In China, people living at the lake-beach level (with hill as a reference point for other elevations) reportedly had the highest odds of getting infected with S. japonicum, a closely related species to S. haematobium [34].
In the father’s occupation category, “other brown-collar jobs” was associated with urogenital schistosomiasis [COR (95 % CI): 1.73(1.19─2.52)], with respondents belonging to this category being about twice [AOR (95 % CI): 1.97 (1.40─2.77)] as likely to be infected compared to those whose fathers jobs belonged to “the white- collar jobs” category. In the mother’s occupation category, “other brown-collar jobs” was significantly associated with the disease [COR (95 % CI): 2.51 (1.29─4.87)], and respondents with mothers in this group are about two times [AOR (95 % CI):1.89 (1.39─2.56)] as likely to be infected compared to those whose mothers’ jobs belonged to the “white-collar jobs” category. The category of “brown-collar jobs” is closely associated with poverty. Parents of such respondents live below USD 4 per day. In addition to this, the network of potable water sources in the study area is very weak [11]. Consequently, people in this job category cannot exclusively rely on wholesome water sources. Studies conducted in Mali and Yemen has shown that level of income is pertinent to the transmission of urogenital schistosomiasis [35, 36].