Prevalence of intestinal protozoan parasites among school children in africa: A systematic review and meta-analysis

Introduction Parasitic infections, especially intestinal protozoan parasites (IPPs) remain a significant public health issue in Africa, where many conditions favour the transmission and children are the primary victims. This systematic review and meta-analysis was carried out with the objective of assessing the prevalence of IPPs among school children in Africa. Methods Relevant studies published between January 2000 and December 2020 were identified by systematic online search on PubMed, Web of Science, Embase and Scopus databases without language restriction. Pooled prevalence was estimated using a random-effects model. Heterogeneity of studies were assessed using Cochrane Q test and I2 test, while publication bias was evaluated using Egger’s test. Results Of the 1,645 articles identified through our searches, 46 cross-sectional studies matched our inclusion criteria, reported data from 29,968 school children of Africa. The pooled prevalence of intestinal protozoan parasites amongst African school children was 25.8% (95% CI: 21.2%-30.3%) with E. histolytica/ dispar (13.3%; 95% CI: 10.9%-15.9%) and Giardia spp. (12%; 95% CI: 9.8%-14.3%) were the most predominant pathogenic parasites amongst the study participants. While E. coli was the most common non-pathogenic protozoa (17.1%; 95% CI: 10.9%-23.2%). Conclusions This study revealed a relatively high prevalence of IPPs in school children, especially in northern and western Africa. Thus, poverty reduction, improvement of sanitation and hygiene and attention to preventive control measures will be the key to reducing protozoan parasite transmission.

• The authors would like to clarify that the primary objective of this systematic review and meta-analysis (SRMA) was to investigate all the intestinal parasites (Protozoa + helminths), but we found that including the names of all intestinal parasites will affect the accuracy of the online database search due to the limitation of the electronic databases, so helminths will be reported in another SRMA that will be conducted by our group as well. • The study's main hypothesis was that the prevalence of intestinal protozoan parasites (IPPs) among school children in Africa is still high, despite the significant improvements in intestinal parasitic diseases identification and mass treatment, as well as in quality of life. • Given that most clinicians and public health professionals may not have the time to find all of the original studies, critically evaluate them, and gather the evidence they want for their queries, systematic reviews may be their greatest source of evidence . As a result, pooling prevalence data on intestinal protozoans in Africa will be useful for understanding the IPPs status among African children and making relevant information more accessible to decision and policymakers. The findings of this study provide additional evidence that the burden of these parasites is still alarming in Africa. • The inclusion and exclusion criteria have been extensively described under the section "Inclusion and exclusion criteria". We hope it's alright now (Line 139-147). • Although sample size was not an inclusion or exclusion criteria, four small studies were excluded during the sensitivity analysis only. The results exhibited that omitting small studies (n < 200) had no significant effect on the summary of the pooled estimates, and the prevalence rate remained within the respective overall prevalence's 95% CI (from 25.8% to 23.9%).
Point 2: Is the study design appropriate to address the stated objectives? Yes, however only cross-sectional studies were included and surveys in hospitals were excluded. I would suggest not to exclude studies according to study design and to use the design as a stratification criteria in analyses. It is worth to check how many studies were excluded by the authors due to design criteria. Moreover, the authors classified the results and meta-analyses by year of publication. Instead, it is more relevant to extract and analyze the studies according to the period of data to show a potential evolution of the prevalence of IPPs especially of some species.
Response 2: Many thanks for your comment.
• The objective of this SRMA was to determine the prevalence of IPPs among school children that is why study conducted in hospital or community level were excluded. • As the cross-sectional studies are the most appropriate study designs for estimating prevalence, including other design would not directly answer our research question rather than incorporating high levels of selection bias. We hope it's understandable now. • Based on the reviewer's excellent suggestion, in the revised manuscript, we have classified and analysed the data based on the time period of the studies (table 2 and supplementary figure 1). We hope it's alright now.

Results
Few recommendations to consider.

General comments
Information provided in this manuscript is important, given the fact that there are no systematic review articles for the African continent on prevalence of intestinal protozoan parasites among school children. Results from this manuscript will clarify the current situation in the continent especially for implementing prevention and control measures. However, there are several limitations which will need to be addressed as follows: Response: Many thanks for your kind words and the critical review Point 1: The data in this manuscript is from 19 African countries only, out of 54 African countries. Furthermore, over 50% of the data is from only three countries namely Ethiopia, Nigeria, and South Africa. How can authors generalise this data for the whole continent? Authors may need to change the title and reflect what is presented. Response 1: The authors strongly agree with this point, the major limitation of this study is the large gap in studies conducted in most African countries. The title, on the other hand, reflects the protocol and the methodology of this systematic review and meta-analysis (SRMA). All the 54 African countries were included in the search strategy, however articles from only 19 countries were identified to meet the inclusion criteria. Indeed, the findings of this SRMA may not accurately reflect the true prevalence status of the intestinal protozoan parasite among children in Africa, but they highlight the large gap in studies conducted in most African countries, highlighting the need for additional studies with different inclusion/exclusion criteria, as well as scholars focusing on intestinal protozoan parasites (IPPs) among school children in these countries. This point has previously been addressed in the discussion section as well as in the study limitation. We hope it's clear now. Many thanks for your comment. Again, from the year 2005 to 2008 only two studies from two countries were analysed i.e., South Africa and Ethiopia. These are the two countries which consistently reported low prevalence of IPPs, therefore stating that there is an increase of prevalence in the whole African region may not be the case because data is from countries with low prevalence.