Assessing the setting-specific individual and joint roles of water contact and sanitation practices on the prevalence of Schistosoma haematobium prevalence in Kano, Nigeria Open Access

Babalola, Chibuzor (Spring 2020)

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BACKGROUND: Nigeria has the highest cases of schistosomiasis in sub-Saharan Africa and accounts for a quarter of the global population requiring treatment. Factors influencing transmission are complex, context-specific, and need to be understood for adequately designed control strategies. This thesis examined the individual and combined roles of water contact and sanitation practices on Schistosoma haematobium prevalence in Kano, Nigeria.

METHODS: A cross-sectional study was carried out in five endemic Local Government Areas of Kano in June and July 2019. Urine samples from school-aged children (4 – 18 years) were screened for S. haematobium and follow up questionnaires were administered to assess participants’ awareness, behavior, and practices. The analytic dataset used 272 participants who had valid laboratory data. Multivariate log-binomial models were used to estimate prevalence ratios (PRs) adjusted for participants’ age, gender, water source, and farming practices.

RESULTS: The prevalence of urinary schistosomiasis for this population was 37.5%; 33.7% of whom reported unimproved sanitation use and 84.6% engaged in at least one of six water contact activities. The majority of participants were male (n=221, 81.6%), and mean age was 11.2 (SD = 4.1). After adjusting for covariates of interest, any degree of water contact (moderate or high) was significantly associated with prevalence, aPR = 3.94, 95%CI [1.68, 9.25]; there was no significant association between unimproved sanitation use and prevalence, aPR = 0.99, 95 CI [0.72, 1.37]; and the observed joint effect of water contact and unimproved sanitation use was significantly associated with infection prevalence; aPR = 3.91, 95%CI [1.68, 9.10].

CONCLUSION: These findings not only suggest that water contact might be the key limiting factor on S. haematobium prevalence for this population when compared to poor sanitation infrastructure alone. The study further highlights complexities in the measurement of WASH constructs within urinary schistosomiasis transmission and provides novel direction for more robust causal research that considers the embedded roles of WASH exposures.

Table of Contents


Rationale  1

Problem statement  3

Purpose statement  6

Research question and hypothesis  7

Significance statement  7


Introduction  9

Possible areas of intervention within the transmission cycle  10

Water sanitation and hygiene in s. haematobium transmission  12

The importance of eco-epidemiological and socioecological context  13

Understanding the role of contact with contaminated water  14

Understanding the role of poor sanitation  16

Overview of situational analyses in Nigeria  18

conclusion  20


Introduction  22

Study area  22

Study population and sample  23

Data collection  23

S. haematobium diagnosis  25

Ethical consideration  25

The data  26

Missing data  26

Outcome measure  26

Main exposures  27

Confounding assessment  27

Modeling effects  28

iv. RESULTS  31

Distribution of outcome and exposures  31

Participant characteristics  31

Analytic sample  32

Final model  32

Effects of individual exposures  32

Effect of joint exposure  34

Figure and tables  35


Key Findings  40

Joint Association  40

Contact with contaminated water  42

Sanitation  44

Strengths and Limitations  46

Implications for practice and research  47

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