Mohammed, Kabiru
(2015)
Epidemiological study and potential of late PCR for diagnosis of schistosomiasis in North Western region of Nigeria.
Masters thesis, Universiti Sains Malaysia.
Abstract
Background: Schistosomiasis is considered the most common and widespread
parasitic infection with significant socio-economic and public health concern
worldwide and continues to be a significant cause of morbidity and mortality in
developing and underdeveloped countries, including Nigeria.
Objectives: This study aimed to determine the prevalence and risk factors associated
with infections by S. haematobium and S. mansoni in three states of North-western
Nigeria, and to develop and evaluate Linear-After-The-Exponential- Polymerase
Chain Reaction (LATE-PCR) LFA for the detection of S. haematobium and S.
mansoni in urine and stool samples. The latter was performed to establish and
enhance accurate diagnosis of Schistosomiasis infection.
Materials and Methods: Conducted in two phases. The first phase of the study was
a cross-sectional survey, conducted between September, 2011 to September, 2012.
Participants were selected based on simple random sampling. Structured
questionnaire was used to assess socio-demographic information, and other
associated determinant factors of the participants. Stool samples were examined
using microscopy and formol ether concentration techniques while urine samples
were examined using Filtration concentration techniques. Data were entered and
analyzed using SPSS version 22.0 statistical software. Simple and multiple logistic
regressions and chisquare test were used to explore the relationships between
associated risk factors. Statistical significant was taken at the 5% level.
The second part of the study involved development of LATE-PCR dipstick method
to establish and enhance accurate diagnosis of S. haematobium and S. mansoni
infection .Primers and probes targeting for, were designed for the two species
specific amplification. The LATE-PCR LFA parameters were optimized and
detection of PCR products was performed on 2% agarose gel electrophoresis, the
nitrocellulose membrane was coated with biotinylated anti-mouse IgG (control line),
anti-FITC (target line) and assembled as lateral flow strips.
Results: Based on the 2451 participants, the study showed an overall prevalence of
infection with S. haematobium to be 61.2% while the prevalence with Schistosoma
mansoni parasites was 54.7%. The majority of the respondents were males (85.5%).
Among the school children the highest prevalence of infection was detected in the
10-14 years (68.4% ). In Univariable analysis, children who belonged to low income
household were 1.43 times highest odds of being infected with S. haematobium [
COR: 95% CI, 1.02, 2.00) p-value 0.042) as compared to those belonging to
household families with monthly income of >USD 500. S. mansoni showed no
significant association between income and risk of infection. Other factors that were
found to be associated with S. haematobium infection in univariate analysis includes
marital status whereby being single had more odds of getting infection compared to
married respondents with (COR 1.97 (95% CI, 1.41:2.76; P=0.001).
In final established multivariate analysis model, risk factors that remain significantly
associated with Schistosomiasis infection include age group, snail contact, rented
house, pit latrine system, Open space toilet and hands contact with water from the
river. For S.haematobium infection risk factors were age group 5-17 (AOR,2.10
:95% CI,1.29,2.06,P=0.001), 18-29 years (AOR,1.37;95% CI: 1.08,1.74, P=0.007), Snail contact (AOR: 1.34,95% CI: 1.07,1.67,P=0.009), Rental house (AOR,1.61,
95% CI: 1.17,2.19: P=0.001), while for S. mansoni the main risk factors in the final
established multivariable analysis model were Snail contact (AOR,1.44,95%
CI:1.09,1.70, P=0.006), Pit system (AOR,0.68,95% CI:0.56,0.84,P=0.001) and
lastly open space defaecation (AOR: 1.26, 95% CI: 1.06,1.51,P=0.009). The study
findings revealed that age group, snail contact and defeacating in an open space was
some of the major determinant risk factors for both species of schistosomiasis, it was
thus therefore recommended that policy decision makers should intensify effort
towards creating awareness through health education for prevention and control.
The LATE-PCR LFA detected schistosoma DNA as low as 1 fg/μl of parasite DNA
in urine and 1 ng/μl of DNA in stool samples.. The amplification reaction showed to
be specific without any cross reaction with DNA from other intestinal microorganism
Conclusion: The prevalence of schistosomiasis recorded in this study was extremely
high and requires effective control and management strategies. Adult age group
exposed to fishing and farming occupation, crossing river bare footed, snail contact, and
rented house are some of predisposing factors identified for S. haematobium and S. mansoni
infection in North-western, Nigeria. LATE-PCR LFA developed in this study provides
a valuable alternative for the detection of S. haematobium and S. mansoni infection
in the study area to speed up diagnosis in addition to the conventional method
currently used.
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