Parasitology Research (2025) 124:58

https://doi.org/10.1007/s00436-025-08504-1

RESEARCH

A comparative analysis of the prevalence and intensity

of schistosomiasis and soil-transmitted helminth infections
between preschool-aged children and school-going children
in KwaZulu-Natal Province
Tafadzwa Mindu1,2 · Nathan Chanhanga1 · John Mogaka1 · Moses Chimbari1

Received: 3 October 2024 / Accepted: 14 May 2025

© The Author(s) 2025

Abstract
The World Health Organization (WHO) recommends conducting a baseline survey to quantify the infection burden of
schistosomiasis and soil transmitted helminths (STH) in pre-school aged children (PSAC) and school-aged children (SAC)
before implementing a schistosomiasis mass drug administration intervention. The objective of the study was to compare the
prevalence and intensity of schistosomiasis and soil-transmitted helminth (STH) infections between preschool-aged children
(PSAC) and school-age children (SAC) in the province of KwaZulu-Natal, South Africa. The study was conducted in the
province of KZN. The target population was PSAC and SAC, with a sample size of 2000 children (1176 primary school-aged
children and 824 pre-school-aged children). Ethical clearance was obtained from the Biomedical Research Ethics Commit-
tee of the University of KwaZulu-Natal; informed consent from parents/legal guardians and verbal assent from SAC were
solicited. Data collection involved collecting stool and urine samples from children. The prevalence and intensity of infections
were compared between PSAC and SAC, using statistical methods to assess differences. The results showed that 49 (4.2%)
SAC were positive for Schistosoma haematobium, while only 3 (0.41%) PSAC were infected. The total number of STH
infections among participants was 281 (22%), with 91 in PSAC and 190 in SAC. The chi-square test showed that SAC were
infected with schistosomiasis more than PSAC counterparts in the same location. However, the difference in STH prevalence
between PSAC and SAC was not statistically significant, suggesting that there was not much of a difference in the prevalence
of STH among SAC and PSAC. Among the STH infections, Taenia was the most prevalent, affecting approximately 20.5% of
SAC and 23.4% of PSAC. This species accounted for a substantial proportion of the overall STH burden in both age groups.
The study concluded that while SAC has a higher overall prevalence, a real burden exists among PSAC indicating the need
to include them in MDA programs targeting S. haematobium in the province.

Keywords Schistosomiasis · Soil-transmitted helminths · Preschool-aged children · School-going children · Public health
policy

Introduction

Globally, an estimated 230 million individuals are afflicted

Handling Editor: Julia Walochnik by schistosomiasis, while 1 billion people suffer from STH
infections, with more than 90% of these cases occurring in
* Tafadzwa Mindu sub-Saharan Africa (Midzi et al. 2014). In South Africa, 25
mindutafadzwa@gmail.com
million people are at risk of contracting schistosomiasis, and
1
School of Nursing and Public Health, College of Health each year approximately 5.5 million new cases are recorded
Sciences, University of KwaZulu Natal, Durban 4001, (Lai et al. 2015). Schistosomiasis affects six of the nine
South Africa provinces in South Africa, namely KwaZulu-Natal, Lim-
2
Department of Psychiatry, Social & Behavioral Sciences, popo, Mpumalanga, Gauteng, North West and the Eastern
Faculty of Medicine, National University of Science Cape (Kabuyaya et al. 2017). A similar pattern is observed
and Technology, Bulawayo 40000, Zimbabwe

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 58 Page 2 of 13 Parasitology Research (2025) 124:58

for STH. The high prevalence of schistosomiasis and STH is bodies and are often exposed to the same infected water
closely associated with poverty, poor environmental hygiene that the SAC are exposed to when they play in the water
and impoverished health facilities (Hotez, Bundy et al. 2006, bodies. Our study therefore determined and compared the
Senghor et al. 2014; Opara et al. 2021). prevalence of schistosomiasis and STH between SAC and
Schistosomiasis and soil-transmitted helminths (STH) are PSAC in KwaZulu-Natal. We also compared the differences
among the most prevalent neglected tropical and subtropi- in egg intensity for infections in both groups. The overarch-
cal diseases (Bowie et al. 2004; Mutapi et al. 2011). Schis- ing research question guiding the study was: is there a dif-
tosomiasis is caused by parasitic trematodes of the genus ference in the burden of schistosomiasis and STH infection
Schistosoma, with three primary species affecting humans: between preschool-aged children (PSAC) and school-age
S. haematobium, S. mansoni and S. japonicum (Knopp et al. children (SAC) in the province of KwaZulu-Natal? This cen-
2013). The most prevalent soil transmitted helminth (STH) tral research question was further broken down into specific
are Ascaris lumbricoides, Trichuris trichiura and the hook inquiries: What is the difference in the prevalence of schis-
worms (Ancylostoma and Necator americanus) (Kirwan tosomiasis and STH between PSAC and SAC in the province
et al. 2009). Schistosomiasis and STH inflict a significant of KwaZulu-Natal, South Africa?; What is the difference
burden on the world’s poorest populations living in rural or in the intensity of schistosomiasis and STH between PSAC
deprived urban settings (Hotez and Kamath 2009). and SAC in the province of KwaZulu-Natal, South Africa?
The most vulnerable groups affected by schistosomiasis By addressing these research questions, the study sought to
and STH are pre-school age children (PSAC), school-age shed light on the comparative burden of schistosomiasis and
children (SAC), women of childbearing age and individuals STH infections between PSAC and SAC in KwaZulu-Natal.
engaged in activities involving contact with contaminated
water, such as fishermen, irrigation farmers and domestic
chores (Mutsaka-Makuvaza et al. 2019; Jeza et al. 2022;
Materials and methods
Phillips et al. 2022). These infections adversely affect adults’
work capacity and fitness while stunting the growth and
Study area
reducing the learning ability of children (De Sanctis et al.
2021).
The study was conducted in the KwaZulu-Natal (KZN)
Despite WHO recommendations to include PSAC in
province of South Africa. KZN has 11 districts, covering a
MDA programs (Organization 2020), data on infection
total area of 94,362 k­ m2 with a population of 10.7 million.
burden in this age group remain scarce, particularly in
The province experiences a tropical to subtropical climate
South Africa, where MDA programs are still in the plan-
characterized by a hot and wet summer (Nov. to Feb.) and a
ning stages. There are still issues that need to be dealt with
cool and dry winter (June to August). Most of the districts
including accessing the children especially those not in Early
in the province have very poor communities with limited
Childhood Development Centres (ECDs) and limitations
access to water sanitation hygiene (WASH) facilities; these
associated with intake of praziquantel in its solid form. The
conditions contribute to the spread of infectious diseases like
introduction of paediatric praziquantel makes it imperative
schistosomiasis and soil-transmitted helminths (Mulopo and
to establish the distribution and intensity of schistosomia-
Chimbari 2021).
sis infections among the PSAC to inform plans for delivery
of the drugs. However, this drug is not yet up for donation
making it inaccessible to the most needy children in Africa Ethics and gate keepers’ permission
(European Medicines Agency (EMA), n.d.). South Africa
has yet to roll out its MDA programme for schistosomiasis. The study protocol was approved by the Biomedical
Although WHO’s roadmap for neglected tropical dis- Research Ethics Committee of the University of KwaZulu-
eases (2021–2030) emphasizes the importance of integrat- Natal (BE429/19). Parents or legal guardians, village lead-
ing MDA into broader public health efforts; South Africa is ers, education and district authorities and participating chil-
still in the planning and piloting phases. Taking advantage dren were informed about the purpose and procedures of the
of the planning stage, the data on the burden of disease both study. Written informed consent was obtained from parents
for PSAC and SAC could help in making sure that objective or legal guardians for their children’s participation, and in
decisions are made. addition to this, all SAC provided verbal assent. To ensure
The hypothesis for this study is that schistosomiasis and confidentiality, all parasitological findings were anonymized
STH infection intensity and prevalence are similar among through coding. Children infected with schistosomiasis or/
SAC and PSAC, since they are both exposed to the same and STH were treated with praziquantel (for schistosomia-
risky water contact activities. This hypothesis was based on sis) using the dose pole to determine dose and with alben-
the premise that PSAC accompany their mothers to the water dazole (for STH).
Parasitology Research (2025) 124:58 Page 3 of 13 58

Study design and sampling two microscopists. The infection intensity was quantified
as eggs per 10 ml of urine under a light microscope (Mott
This study was a cross-sectional study targeting PSAC and et al. 1982).
SAC in the whole province of KZN. Data was collected S. mansoni and STH were examined using the Kato-Katz
between 2020 and 2021. The sample size was calculated thick smear technique (Katz et al. 1972). To view the stool
using the Krejcie and Morgan formula for calculating a sample under a microscope, the procedure involved plac-
sample size to represent a population with unknown disease ing a labelled glass slide and a 41.7-mg plastic template on
prevalence. To estimate the burden of schistosomiasis and top. To ensure even distribution of eggs and clear view of
soil transmitted helminth infection among pre-school age eggs, the faecal sample was placed on a nylon screen and
in KwaZulu-Natal province of South Africa, assuming 95% pressed on top, to remove solid particles that would block
confidence and an acceptable margin of error of 5% and the view of eggs. The sieved faecal material was scraped
maximum variability, i.e., 50% (given unknown previous through the screen and then placed inside the hole of the
prevalence), a sample size of 120 subjects per district was plastic template. The template was then removed, leaving
required. The sample was further increased by a margin of the faecal sample caked on the slide. One piece of the cel-
15% to account for potential non-response and multiplied by lophane, which has been soaked overnight in methylene blue
a design effect (D) of 1.5. Hence, the final sample size of the glycerol solution was placed over the faecal sample (Hong
study was 150 PSAC and 150 SAC per district. Increasing et al. 2003). Then, a clean slide was placed over the top and
the sample size reduced the type I and type II errors as well pressed evenly downwards to spread the faeces in a circle.
as known and unknown confounder effects. Hence, power of The slide was carefully removed by gently sliding it side-
the sample (1-𝛽 ) and (the % chance of detecting difference) ways to avoid separating the cellophane strip. The slide with
of the study was set at 80%. the cellophane was placed upwards under a microscope and
For each district we aimed to sample at least of 150 PSAC examined in a systematic zig zag pattern. The number and
and 150 SAC. To achieve this, we selected 8 schools (taking type of egg of each species was recorded on the recording
8 primary schools and 8 preschools) per district. We sys- form alongside the same number. Finally, the number of
tematically sampled using a sampling tool accessed online eggs was multiplied by 24 to give the number of eggs per
(RANDOM.ORG — List Randomizer, n.d.). We selected 8 gram (Hong et al. 2003).
schools per district using the KwaZulu-Natal Department of The template was placed in a bucket of water mixed with
Basic Education list of primary schools. We then identified detergent, and a piece of cellophane is placed over the fae-
an ECD nearer to the school to recruit the PSAC age group. cal sample. The number and type of egg of each species
We did not include children who were at home (non-school were recorded on the recording form. Thick faecal smears
going); we only recruited children that where either in a pre- were then observed within 1 h using a light microscope. The
school, ECD centre, or primary school. In some instances slides will be left to clear for 24 h.
there was no pre-school nearby and in such cases we would
recruit learners in the ECD class within the schools identi- Data analysis
fied. eThekwini district was divided into two districts by
the KwaZulu-Natal Department of Basic Education, hence During the sample collection stage, participant data was
in our study, we considered Umlazi and Pinetown as sub- collected, including age, sex, grade, school and district.
districts and sampled 8 schools in each of them. Each child was assigned a code, and this code was labelled
on specimen bottles. Data was recorded in an Excel form,
Specimen collection and processing and microscopy results were recorded against the code for
each sample. These codes were matched with the children’s
All children were provided with two containers for stool and details, and the reports including egg counts for schistoso-
urine collection, and parents or caregivers of PSAC were miasis and STH.
invited to assist in collecting samples. Only children with The quantitative data was cleaned and imported to SPSS
signed consent forms participated in the study. The team version 20 as well as DataTab for statistical analysis. Data
labelled specimen containers with unique codes and filled cleaning involved coding responses, names, gender and
information on an Excel form for each child. infection statuses of participants, identifying missing data
For S. haematobium, we collected urine from participants and removing incomplete entries and outliers. Data outliers
using a 100-ml plastic bottle container. Using a syringe, were resolved using capping, transformation and removal.
we extracted and processed 10 ml of the urine sample by Consistency checks included data type validation, range
syphoning it through a 25-mm diameter polycarbonate fil- checks, duplicate removal and cross-validation to ensure
ter membrane (NucleoporeTM filter). Eggs were stained each column contained the correct data type; values fell
with 50% Lugol’s iodine saline solution and counted by within expected range, and unique entries. Cross-validation
 58 Page 4 of 13 Parasitology Research (2025) 124:58

checks were conducted for consistency across related fields. The study categorized common STH infections into light,
Descriptive analysis including frequency, mean and percent- moderate and heavy infection intensity using WHO standard
age was used to summarize the demographic characteristics procedures. Experienced medical practitioners and labora-
of the study participants. tory technologists performed the procedures, and some stool
samples were randomly selected for quality control.
Variables

Prevalence was defined as the percentage number of indi- Results

viduals positive for any of the infections over the number
that submitted samples for examination. Infection intensity Socio‑demographic characteristics of study
was defined as the average number of egg counts expressed participants
as arithmetic mean eggs per gram of faeces (epg). Schisto-
somiasis infections (prevalence) as well as STH infection A total of 2000 children participated in the study; 1176
and intensity were the dependent variables, while the pupil school-aged children (SAC) and 824 pre-school aged chil-
grade (categorised as PSAC and SAC), district and other dren (PSAC). The age range was 1–15 years. PSAC average
demographic factors such as age and sex were the independ- age was 5 (range 1–6), while SAC average age was 9 (range
ent study variables. 8–11). Some learners failed to produce stool samples; hence,
the total for STH samples was 1275 (459 PSAC = and 816
Statistical tests SAC). Details on demographic characteristics are in Table 2.
About half (n = 1012; 50.6%) of the study participants
Prevalence and average intensity of infections were cal- were females and (n = 988 − 49.4%) males. The number of
culated for STH and S. haematobium (no S. mansoni was school-age children (SACs) was (n = 1176 − 58.1%), while
recorded). Confidence intervals (CIs) of 95% were obtained (n = 838 − 41.9%) were preschool-aged children (PSAC).
using binomial and negative binomial regression models, There were no significant differences between PSAC and
respectively, considering clustering at school or village lev- SAC participants in terms of gender ­(X2 = 2.371, p = 0.124).
els. We used the negative binomial model since the distribu- For preschool-aged children, the age ranged from 1 to
tion of egg counts was over dispersed. Further, we compared 6 years with a mean age of 5 years. At least one class per
the prevalence between PSAC and SAC using the chi-square grade was taken to represent PSAC or SAC. The total num-
test for difference in prevalence. We also used the z-test sta- ber varied from school to school. Eight primary schools
tistic for two-sample test of proportions reporting the z-test and 8 preschools were screened from each district. Due to
statistic and the associated p-values. COVID-19 regulations, the program faced challenges in get-
Screening of STH eggs was based on a 41.7 mg Kato ting more participants because schools operated on a half
Katz template to determine the parasite’s egg per gram in class basis. It was also not possible to cover all the schools
the stool (EPG) by calculating the number of eggs counted that had been sampled leading to some districts having less
multiplied by 24. Table 1 shows how STH intensities were than eight schools being screened. The highest number of
categorised in accordance with WHO standards. participants came from Amajuba (n = 261–13%) followed
The study used chi-square test to analyse variables, calcu- by Zululand (n = 236 — 11.6%) and uMzinyathi (n = 226
lated the geometric mean intensity of parasite EPG in stool — 11.3%). The lowest was from iLembe district with 124
for infected and non-infected individuals and used inde- participants in total.
pendent samples t-test to compare STH infection intensity
between PSAC and SAC. Bivariable analysis was performed Comparing Schistosoma haematobium prevalence
to examine the association between independent and depend- between PSAC and SAC
ent variables, with a p-value of < 0.05 considered statisti-
cally significant. Out of 1176 school-age children screened, 49 (4.2%) were
positive for S. haematobium with a mean of 52.6 eggs/10
ml. Out of the 824 preschool-aged children screened, only
3 (0.4%) were infected with S. haematobium with a mean
Table 1  STH intensities, categorised by on WHO standards of 13.2 eggs/10 ml. The intensity range in SAC was 1–250
Light Moderate Heavy eggs/10 ml and 8–35 eggs/10 ml in PSAC.
S. haematobium infections were more prevalent in coastal
Ascaris 1–4999 5000–49,999 ≥ 50,000
districts such as eThekwini, Ugu and iLembe (Fig. 1). For
Trichuris 1–999 1000–9999 ≥ 10,000
primary school-aged children, S. haematobium was more
Hookworm 1–1999 2000–3999 ≥ 4,000
prevalent in rural schools than in urban areas. For example,
Parasitology Research (2025) 124:58 Page 5 of 13 58

Table 2  Demographic characteristics of the study participants

S. haem (n = 2000) STH (n = 1275)
Samples (n) Positive (n) Prevalence (%) Samples (n) Positive (n) Prevalence (%)

Gender Females 1012 26 2.6% 638 145 22.7%

Males 988 26 2.6% 637 136 21.4%
Grade PSAC 824 3 0.4% 459 91 19.8%
SAC 1176 49 4.2% 816 190 23.3%
1 2 0 0.0% 1 0 0.0%
2 8 0 0.0% 2 0 0.0%
3 25 0 0.0% 10 2 20.0%
4 86 2 2.3% 42 8 19.0%
5 528 1 0.2% 305 60 19.7%
6 190 1 0.5% 110 21 19.1%
7 60 1 1.7% 47 10 21.3%
8 433 9 2.1% 309 68 22.0%
9 516 28 5.4% 343 9 26.8%
10 123 5 4.1% 83 15 18.1%
11 22 4 18.2% 19 3 15.8%
12 4 0 0.0% 3 1 33.3%
13 2 1 50.0% 1 1 100.0%
15 1 0 0.0%
Age
District Amajuba 261 0 0.0% 100 14 14%
iLembe 124 4 3.2% 91 7 8%
King Cetshwayo 170 5 2.9% 130 18 14%
Ethekwini (Pinetown) 200 3 1.5% 122 64 52%
Sisonke 151 0 0.0% 109 10 9%
Ugu 160 15 9.4% 124 12 10%
Umgungundlovu 152 5 3.3% 68 2 3%
Ethekwini (Umlazi) 162 4 2.5% 132 37 28%
Umzinyathi 226 2 0.9% 126 52 41%
Uthukela 158 0 0.0% 124 22 19%
Zululand 236 14 5.9% 161 43 25%

Zululand, a rural district had a prevalence of 9.3%, almost S. haem positive, p = < 0.001. The calculated p-value of
double that of Umlazi, an urban district with 4.4%. Only < 0.001 was lower than the defined significance level of 5%
three primary school children (all boys) had visible haema- (see Table 4). The c­ hi2 test was therefore significant, and the
turia and none for PSAC. There was no gross haematuria null hypothesis was rejected. Simply, there was an increase
in urban districts for both PSAC and SAC. Table 3 shows in infection with every increase in the grade of the children.
details on the prevalence and infection intensity of S. hae- A child was more likely to get infected with S. haematobium,
matobium among the two comparison groups. if they were SAC than if they were PSAC.

Chi‑square test of correlation Logistic regression test

The results from the ­chi2 test showed a significant difference The study examined the impact of grade, sex and age on
in the prevalence of S. haematobium among PSAC and SAC. Schistosoma haematobium infection (Table 5). We found
The chi-square test shows that there is a statistically signifi- that being SAC increased the odds of S. haematobium
cant relationship between grade and S. haem positive, χ2(1) infection by 1.07, with an odds ratio of 2.92. This means
= 27.67, p = < 0.001, as seen in Table 4. A Fisher exact test that the odds of SAC being positive were 2.92 times as
was performed between grade and S. haem positive, show- likely compared to PSAC. This, however, was not statisti-
ing a statistically significant relationship between grade and cally significant (p = 0.174). Being female decreased the
 58 Page 6 of 13 Parasitology Research (2025) 124:58

Fig. 1  The distribution of infec-

tions in the district, S. haema-
tobium infections in primary
schools are shown in yellow,
and preschool infections are
shown using the blue dots. The
smaller dots show study sites
with zero records of infection;
some of them appear to be in
one colour because two dots
are sitting on top of each other;
these are schools with both SAC
and PSAC

Table 3  Prevalence of S. haematobium infections among the two comparison groups (PSAC and SAC)
District School-age children Preschool-aged children
Total S. haem + (n) S. heam prev (%) Mean intensisy Total S. haem S. heam prev (%) Mean intensity
screened screened P + (n)
(n) (n)

Amajuba 119 0 0.0% 0.00 142 0 0.0% 0.00

iLembe 89 4 4.5% 3.28 35 0 0.0% 0.00
King Cetshwayo 111 5 4.5% 15.92 59 0 0.0% 0.00
Ethekwini — Pinetown 142 3 2.1% 1.48 58 0 0.0% 0.00
Ethekwini — Umlazi 91 4 4.4% 0.55 71 0 0.0% 0.00
Sisonke 85 0 0.0% 0.00 66 0 0.0% 0.00
Ugu 114 15 13.2% 9.59 46 0 0.0% 0.00
Umgungundlovu 75 4 5.3% 2.68 77 1 1.3% 0.08
Umzinyathi 127 1 0.8% 0.32 99 1 1.0% 0.18
Uthukela 90 0 0.0% 0.00 68 0 0.0% 0.00
Zululand 133 13 9.3% 10.33 103 1 1.0% 0.08
Total 1176 49 4.2% 824 3 0.4%

odds of S. haematobium infection by − 0.01, with an odds with an odds ratio of 1.47, suggesting a 46.75% increase
ratio of 0.99. This means that the odds of girls being posi- in the odds of infection with each additional unit of age
tive of S. haematobium were 0.99 times as likely compared (p = 0.005). The p-value of 0.005 is below the conven-
to boys. This analysis was also not statistically signifi- tional 0.05 threshold, indicating that impact of age on S.
cant (p = 0.979). Our findings (in Table 5) show that age haematobium infection was statistically significant at the
increased the odds of S. haematobium infection by 0.38, 5% level.
Parasitology Research (2025) 124:58 Page 7 of 13 58

Table 4  Chi2 test results determining the correlation between S. hae- Distribution of STH infections in KZN
matobium infection and grade (PSAC/SAC)
S. haem positive The highest STH prevalence (52%) is in Pinetown, followed
0 1 Total
by uMzinyathi (41%), uMlazi (28%) and Zululand (25%),
as shown in Table 6. The lowest was uMgungundlovu and
Grade PSAC 821 3 824 iLembe districts at 0.7%, 0.7% and 2.5%, respectively. The
SAC 1127 49 1176 highest prevalence of STH for both SAC and PSAC were
Total 1948 52 2000 recorded in Pinetown urban district, with SAC infections
Chi2 df p being the highest at 44.4% prevalence in the district. There
Grade - S. haem positive 27.67 1 <.001 was considerable variation in prevalence between districts
p ranging from 13 to 44.4%, with very small differences
Left-sided 1 between PSAC and SAC. Refer to Table 6 for more infor-
Two-sided < 0.001 mation on STH prevalence per district. The Taenia species
Right-sided <.001 had the highest prevalence (20.5% in SAC and 23.4 PSAC)
C in both groups and all the districts, followed by Ascaris lum-
Grade — S. haem positive 0.17 bricoides. In all the STH infections, Taenia contributed to
72.8% in both groups.

STH Intensity levels

Comparing STH prevalence between PSAC and SAC
in KwaZulu‑Natal Province STH intensity levels for Taenia, Ascaris and Pinworm
are shown in Table 7, indicating insignificant differences
A total of 816 SAC and 459 PSAC children provided between PSACs and SACs. The mean intensity for A. lum-
stool samples for examination. The total number of bricoides was 3280 eggs/g and 5810 eggs/g among PSACs
STH infections among the study participants who pro- and SACs, respectively; mean intensity for Taenia was 380
vided a stool sample was 281 (22%), out of which 91 and 530 eggs/g in PSACs and SACs, respectively. SAC had
were PSACs and 190 SACs. The prevalence of STH lower infection intensity of A. lumbricoides than PSAC
in PSAC was 20% and that of SAC was 23%. There but a higher intensity of Taenia and Tricuris tricuria than
was no statistical difference between the two groups; PSAC. There were no overall differences in infection bur-
the chi-square test showed that the difference in STH den between both groups; they had a high infection burden
prevalence between PSACs and SACs was not statisti- of A. lumbricoides and Taenia and moderate infections of
cally significant (chi-square value of 2.889, p = 0.089) Trichuris tricuria. Both urban and rural districts had similar
implying that, unlike in the case of S. haematobium, distribution pattern of the STH burden with no differences
the prevalence of STHs among SACs and PSACs was between boys and girls.
similar.
The distribution of STH detected by species was T.
trichiura 18 (1.4%), A. lumbricoides 116 (9%), Tae- Discussion
nia 197 (15.3%), Pinworm (Enterobius vermicularis)
11 (0.8%), Mansoni 1 (0.07%) and Hookworm species This study examined the prevalence and intensity of schisto-
1 (0.07%). Most of infections appeared together as co- somiasis (S. haematobium) infection among primary school-
infections. STH infections were not significantly asso- aged children (SAC) and preschool-aged children (PSAC)
ciated with SAC/PSAC for Taenia (p > 0.344), 3.136 in KwaZulu-Natal Province, South Africa. The study found
(p > 0.07) for Ascaris, 2.955 (p > 0.086) for Trichuria, significant variation in S. haematobium infection across dif-
0.687 (p > 0.407) for Pinworm and 0.562 (p > 0.453) for ferent districts, with Zululand reporting the highest preva-
Hookworms. lence at 9.3%. The study also found that older children were

Table 5  The results of a binary Coefficient B Standard error z p Odds ratio 95% conf. interval
logistic regression analysis,
which looks at how grade, sex, Constant − 7.58 0.94 8.05 < 0.001 0 0–0
age influenced the likelihood
Grade SAC 1.07 0.79 1.36 0.174 2.92 0.62–13.68
of a Schistosoma haematobium
infection Sex F − 0.01 0.28 0.03 0.979 0.99 0.57–1.73
Age 0.38 0.14 2.79 0.005 1.47 1.12–1.92
 58
Page 8 of 13

Table 6  The prevalence of STH infections among the two comparison groups (PSAC and SAC)
School-age children Preschool-aged children
STH STH STH Ascaris Hook- Man- Pin- Taenia Tricuris STH STH STH Ascaris Hook- Man- Pin- Taenia Tricuris
samples Positive Preva- worm soni worm samples Positive Preva- worm soni worm
lence lence

Amajuba 42 7 17% 7 0 0 0 0 0 58 7 12% 4 0 1 0 1 0

iLembe 61 5 8% 2 0 0 0 5 0 21 2 10% 1 0 0 0 2 0
King Cetsh- 88 10 11% 2 0 0 0 8 0 42 8 19% 3 0 0 0 7 0
wayo
Thekwini — 93 50 54% 29 0 0 3 30 10 29 14 48% 12 0 0 4 6 0
Pinetown
Thekwini — 75 26 35% 10 0 0 3 19 2 57 11 19% 3 0 0 0 8 2
Umlazi
Sisonke 63 5 8% 1 0 0 0 4 0 46 5 11% 1 0 0 0 4 0
Ugu 95 7 7% 5 1 0 1 3 0 29 5 17% 2 0 0 0 4 0
Umgungun- 41 1 3% 1 0 0 0 1 0 27 1 4% 1 0 0 0 0 0
dlovu
Umzinyathi 85 35 41% 4 0 0 0 33 3 41 17 41% 3 0 0 0 14 1
Uthukela 74 16 18% 1 0 0 0 13 0 38 8 21% 0 0 0 0 8 0
Zululand 98 28 31% 21 0 0 0 16 0 67 13 19% 3 0 0 0 11 0
Total 815 190 23% 83 1 0 7 132 15 455 91 20% 33 0 1 4 65 3
Parasitology Research
(2025) 124:58
Parasitology Research (2025) 124:58 Page 9 of 13 58

Table 7  The STH intensity STH species Geometrical Mean inten- t-Test Intensity level
levels for the 3 species that sity
were frequently recorded; the
table also shows the statistical PSAC SAC F p value PSAC SAC
differences between PSACs and
SACs Taenia 380 530 0.268 0.775 Light Light
Ascaris 3280 5810 3.481 0.208 Moderate Heavy
Pinworm 7210 260 16.508 0.231 Heavy Light

at a greater risk of S. haematobium infection, which tends to and Gabrielli 2007), our study revealed worrying prevalence
increase with age due to prolonged exposure to contaminated and intensities.
water sources. The study also found that SAC had a higher Among SAC, 4.2% tested positive for S. haematobium,
prevalence of S. haematobium, with 4.2% testing positive for with a mean intensity of 51.6 eggs per 10 ml of urine. The
the disease. The study also found a highly localized distri- presence of visible hematuria, predominantly in primary
bution of the disease, with certain areas being more condu- school-aged boys, serves as a significant clinical indicator
cive to schistosomiasis transmission. The study also found of S. haematobium infection. Notably, no cases of visible
a relatively high burden of soil-transmitted helminth (STH) haematuria were observed among PSAC, highlighting a
infections among both PSAC and SAC, with Pinetown hav- potential difference in disease presentation between the two
ing the highest prevalence. age groups. This age-related difference in symptomatology
may be attributed to variations in the duration and intensity
Prevalence of schistosomiasis infection of water contact activities among children of different age
groups.
The findings of this study provide valuable insights into S. haematobium infections among PSAC were detected
the prevalence and intensity of schistosomiasis (S. hae- in 2 out of the 10 districts surveyed. Among the SAC, it
matobium) infection among primary school-aged children was detected in 7 out of 10 districts surveyed. This finding
(SAC) and preschool-aged children (PSAC) in Kwa Zulu suggests a highly localized distribution of the disease, with
Natal Province, South Africa. Our study reveals a consider- certain areas being more conducive to schistosomiasis trans-
able variation in the prevalence of S. haematobium infec- mission. Our findings on the distribution of S. haematobium
tion across different districts, with Ugu district and Zululand infection in the province corroborate with findings from the
reporting the highest prevalence at 9.4% and 5.9%, respec- study by Nwoko et al. 2023 on the distribution of human
tively. Other districts have 0% prevalence such as Uthukela, schistosome transmitting snails (Balinus globosus) in the
Sisonke and Amajuba. These districts (Uthukela, Sisonke province. They found human schistosome transmitting snails
and Amajuba) are furthest from the coastline and are nestled in 8 districts out of 11 (Nwoko, Manyangadze et al. 2023).
in mountainous regions, hence the low infection rates due The statistical analysis revealed significant differences in
to absence of favourable conditions for the host snails. The infection rates between SAC and PSAC in districts where
districts with high prevalence (Ugu, Zululand and Thekwini) both age groups were affected, particularly in Zululand,
lie in areas where rivers become slow as they approach the which exhibited the highest S. haematobium prevalence.
ocean; this often provides a good environment for snails to This underscores the importance of localized control strat-
breed with the addition of weeds and marshy waters. These egies, as infection dynamics can vary widely even within
districts are also areas with population settlements. This the same province. Importantly the low infection intensities
regional heterogeneity underscores the complex dynamics highlight the need for more sensitive diagnostic measures,
of schistosomiasis transmission, which are influenced by since light infections may not be detected (Utzinger et al.
factors such as local water contact patterns, sanitation and 2015; Rubaba et al. 2018).
access to healthcare (Mari et al. 2017).
The prevalence of SAC was higher than that of PSAC, Prevalence of STH infection
suggesting that older children are at a greater risk of S.
haematobium infection. This is consistent with previous The study also investigated the prevalence and intensity of
research highlighting that the risk of schistosomiasis tends soil-transmitted helminth (STH) infections, revealing a rela-
to increase with age due to prolonged exposure to contami- tively high burden of STH infections among both PSAC and
nated water sources (Verjee 2019). It is, however, important SAC. The overall prevalence rates of 19.8% in PSAC and
to note that contrary to previous thinking that under five 23.3% in SAC indicate that STH infections remain a signifi-
prevalence of schistosomiasis was not significant (Stothard cant public health concern in the study area.
 58 Page 10 of 13 Parasitology Research (2025) 124:58

Pinetown (a suburb district of eThekwini) had the highest trichiura infections. These differences in infection inten-
prevalence of STH infections in both age groups, with SAC sity between age groups may be due to factors such as
exhibiting a slightly higher prevalence at 54%, compared to exposure patterns, immunity and host susceptibility.
48% for PSAC. This was unexpected in an urban district; It is worth noting that the prevalence in this study was
however, the high prevalence was contributed by two schools lower than those previously found in the same province
which are located close to informal settlements, where there (Kabuyaya et al. 2017; Manyangadze et al. 2021), and the
is poor sanitation and poor living conditions. This disparity lower prevalence may be due to preceding droughts. Preva-
in infection rates may be linked to differences in hygiene lence of infection generally decreases during prolonged
and sanitation practices, highlighting the need for targeted droughts over years due to declining snail populations and
interventions in urban areas. rise again after wet spells (Rubaba et al. 2016).
Among the STH infections, Taenia was the most preva-
lent, affecting approximately 20.5% of SAC and 23.4% of
PSAC. This species accounted for a substantial proportion of Study’s contributions and potential implications
the overall STH burden in both age groups. The prevalence
of Taenia infections suggests a potential zoonotic transmis- The findings of this study have several important implica-
sion, emphasizing the importance of a One Health approach tions for public health policy and future research efforts.
in addressing STH infections in the study area. Wildlife and Firstly, our results underscore the importance of tailored
animals have been shown to be reservoirs of Taenia that has interventions for schistosomiasis and STH control, con-
been linked to human infection (Deplazes et al. 2019). sidering the local epidemiological context. Geographical
At the provincial level, no significant difference in STH variations in disease prevalence and intensity within Kwa-
infection burden was observed between SAC and PSAC, Zulu-Natal Province necessitate region-specific strategies
indicating that both age groups share a similar risk of STH to maximize the impact of control programs. As many
infections. However, at the district level, variations in infec- African counties with low endemicity move towards elimi-
tion rates were noted, with Pinetown and uMzinyathi dis- nation of schistosomiasis, there is a need for targeted con-
playing statistically significant distinctions between PSAC trol of infected individuals or regions to avoid develop-
and SAC. These district-level variations may be attributed to ment of resistance to the only available drug praziquantel
differences in environmental and socioeconomic factors that (Tchuenté et al. 2017).
influence STH transmission. Pinetown had a high number of Secondly, the observed high prevalence and intensity
informal settlements leading to poor sanitation and hygiene of STH infections among both PSAC and SAC emphasize
which generally increase STH infections. UMzinyathi also the urgency of integrated STH control measures, includ-
had socio-economic problems which included poor access ing regular deworming, hygiene education and improved
to water and sanitation facilities. sanitation facilities in schools and communities. These
measures should be extended to preschools, as our study
highlights that PSAC are equally susceptible to STH
Schistosomiasis Intensity and STH Infection infections.
Intensity Lastly, the absence of S. haematobium infections in
several provinces among PSAC raises questions about the
This study also evaluated the intensity of schistosomiasis need for specific intervention strategies targeting this age
and STH infections in both PSAC and SAC. Notably, the group. Future research should focus on developing diag-
mean intensity of S. haematobium infection was lower in nostic tools suitable for PSAC, as well as evaluating the
PSAC (13.2 eggs per 10 ml) compared to SAC (52.6 eggs feasibility and effectiveness of treatment programs for this
per 10 ml). The broader range of intensity observed in SAC, vulnerable population.
ranging from 1 to 250 eggs per 10 ml, highlights the poten- This study provides critical insights into the prevalence
tial for more severe infections among primary school-aged and intensity of schistosomiasis and STH infections in
children. Furthermore, the presence of gross haematuria PSAC and SAC within KwaZulu-Natal Province. These
solely in SAC, particularly in the high-prevalence district findings contribute to the evidence base for informed
of Zululand, underscores the clinical severity of schistoso- public health policies and underscore the need for region-
miasis in this age group. specific control measures and further research to address
In contrast, STH infections, particularly A. lumbri- the neglected tropical diseases affecting young children in
coides, displayed higher mean intensity in PSAC (5810 South Africa. Our study is opportune in that South Africa
eggs/g) compared to SAC (3280 eggs/g). However, SAC still has to roll out its MDA programme; therefore, the
exhibited higher intensities of Taenia and Trichuris results will provide good baseline data for the programme.
Parasitology Research (2025) 124:58 Page 11 of 13 58

Limitations PSAC across different districts. The overall prevalence of SAC

was higher than that of PSAC, suggesting that older children
Our study was meant to cover the whole of KwaZulu- are at a greater risk of S. haematobium infection. However, the
Natal, but because of COVID-19 restrictions and poor study proved that a real burden existed among PSACS which
enrolments for PSAC, we were not able to collect data in needs to be addressed. While no significant difference in STH
some districts and in some schools. infection burden was observed between SAC and PSAC at
One of the limitations of our study was sample representa- the provincial level, district-level variations were prominent.
tiveness; our sample was calculated at the provincial level, Notably, the mean intensity of S. haematobium infection was
where we chose ten schools per district to represent all the lower in PSAC compared to SAC. In contrast, STH infections,
schools in the province. The limitation is that while the sample particularly A. lumbricoides, displayed higher mean intensity
gives a true prevalence at the provincial level; it does not repre- in PSAC compared to SAC. However, SAC exhibited higher
sent prevalence accurately at the district level since population intensities of Taenia and Trichuris trichiura infections. The
and number of schools vary per district. As a result, our find- study also revealed a relatively high burden of STH infections
ings may not paint a true picture of the prevalence at district among both PSAC and SAC.
level, but they show existence of infection in a district. The Clinical trial number: Not applicable.
other implication is that in areas where we found infections,
Acknowledgements We acknowledge the support of the KwaZulu-
the prevalence may be higher than what we recorded. This Natal Department of Health, educational institutions and the partici-
necessitates further research in the districts which recorded pating children and their families. This research would not have been
infections to determine the exact extant of the problem. possible without their cooperation and contributions. The authors
In terms of data collection, the most significant limita- appreciate the efforts of the TIBA research team and community
research assistants that assisted in the data collection process. Thanks
tion was the low stool sample supply. Children aged 5 years to Nokwanda Majola and Ntombela Sambulo for the administrative and
and below often struggled to produce stool samples, while technical support provided. Special thanks goes to Dr Owen Rubaba
the older (school-aged children) did not have much of a for doing the microscopy and assisting in the identification of infected
problem. Eventually we had a low stool sample count com- participants.
pared to urine. This was, however, rectified using our statis- Author Contributions Conceptualization, NC and M.J.C.; methodol-
tics models that allowed us to adjust the level of statistical ogy, NC; formal analysis, T.M., NC., J.M., and M.J.C.; writing—origi-
confidence based on the samples received. nal draft preparation T.M., NC., J.M.; writing—review and editing,
Another limitation was the difference in sample size T.M., N.C., J.M., and M.J.C.; supervision, M.J.C.; funding acquisition,
M.J.C. All authors have read and agreed to the published version of
between PSAC and SAC groups — the PSAC group had the manuscript
fewer participants. This difference was due to COVID-19
associated constraints encountered in the field such as fewer Funding Open access funding provided by University of KwaZulu-
ECD centres, compared to primary schools, and low enrol- Natal. This research was funded by Tackling Infections to Benefit
Africa (TIBA) through grant UoERef:CT-4987 (d) and the University
ment of preschool aged learners in schools offering ECD of KwaZulu-Natal through An MPhil studentship bursary awarded to
education. To mitigate this disparity in sample size, specific NC by the College of Health Sciences. The views expressed in this
statistical methods such as c­ hi2 test and logistic regression publication are those of the author(s) and not necessarily those of the
analysis were employed, and the analysis focused on identi- TIBA. APC charges were funded by UKZN.
fying clear effect sizes. The results of the PSAC group were Data Availability No datasets were generated or analysed during the
interpreted with caution, acknowledging potential reduced current study.
statistical power compared to the SAC group.
Declarations
Institutional Review Board statement The University of KwaZulu
Natal biomedical research ethics committee (BREC) issued the ethical
Conclusion approval for the protocol: Comparative analysis of the burden of schis-
tosomiasis and soil transmitted helminth infection between pre-school
In light of the pressing need to address the burden of schis- age children in the province of KwaZulu-Natal. Degree: MMedSc.
BREC Ref No: BE429/19.
tosomiasis and soil-transmitted helminth (STH) infections
in children below the age of 5, our study bridged a critical
Informed consent statement Informed consent was obtained from all
knowledge gap by comparing the prevalence and intensity of subjects involved in the study.
these infections between preschool-aged children (PSAC) and
primary school-aged children (SAC) in KwaZulu-Natal Prov- Conflicts of interest The authors declare no conflicts of interest. The
ince, South Africa. Our study revealed considerable variation funders had no role in the design of the study; in the collection, analy-
in the prevalence of S. haematobium infection in SAC and
 58 Page 12 of 13 Parasitology Research (2025) 124:58

ses, or interpretation of data; in the writing of the manuscript; or in the children from semi-urban communities in Nigeria: a double-blind
decision to publish the results. placebo-controlled randomised trial. BMC Infect Dis 9(1):20.
https://​doi.​org/​10.​1186/​1471-​2334-9-​20
Open Access This article is licensed under a Creative Commons Attri- Knopp S, Becker SL, Ingram KJ, Keiser J, Utzinger J (2013) Diagnosis
bution 4.0 International License, which permits use, sharing, adapta- and treatment of schistosomiasis in children in the era of inten-
tion, distribution and reproduction in any medium or format, as long sified control. Expert Rev Anti Infect Ther 11(11):1237–1258.
as you give appropriate credit to the original author(s) and the source, https://​doi.​org/​10.​1586/​14787​210.​2013.​844066
provide a link to the Creative Commons licence, and indicate if changes Lai Y-S, Biedermann P, Ekpo UF, Garba A, Mathieu E, Midzi N,
were made. The images or other third party material in this article are Mwinzi P, N’Goran EK, Raso G, Assaré RK (2015) Spatial dis-
included in the article’s Creative Commons licence, unless indicated tribution of schistosomiasis and treatment needs in sub-Saharan
otherwise in a credit line to the material. If material is not included in Africa: a systematic review and geostatistical analysis. Lan-
the article’s Creative Commons licence and your intended use is not cet Infect Dis 15(8):927–940. https://​doi.​org/​10.​1016/​S1473-​
permitted by statutory regulation or exceeds the permitted use, you will 3099(15)​00066-3
need to obtain permission directly from the copyright holder. To view a Manyangadze T, Chimbari MJ, Rubaba O, Soko W, Mukaratirwa S
copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. (2021) Spatial and seasonal distribution of Bulinus globosus and
Biomphalaria pfeifferi in Ingwavuma, uMkhanyakude district,
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