Abstract
Background
Intestinal parasitic infections (IPIs) remain a significant public health concern worldwide, particularly affecting children under five years old. These infections contribute to malnutrition, impaired growth, diarrhea, and increased morbidity and mortality, disproportionately impacting low- and middle-income countries. This systematic review and meta-analysis aims to estimate the global prevalence of IPIs in children under five and examine the influence of socioeconomic, environmental, and diagnostic factors.
Methods
A systematic literature search was conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines across multiple databases (PubMed, Web of Science, Scopus, ScienceDirect, and Google Scholar) for cross-sectional studies reporting the prevalence of IPIs in children under five years old, up to November 2025. The pooled prevalence was estimated using a random-effects meta-analysis, and subgroup analyses were performed by region, human development index (HDI), income level, climate, diagnostic method, and parasite species. Methodological quality was assessed using an adapted Newcastle–Ottawa Scale.
Results
Forty-one studies, involving a total of 15,109 children under five, met the inclusion criteria. The study population was drawn from multiple regions worldwide. The overall pooled prevalence of IPIs in children under five was 31.60% (95% CI: 26.04–37.44). Prevalence was highest in lower-middle-income countries (37.45%) and low-HDI regions (35.17%), and lowest in high-income countries (6.25%) and very high-HDI regions (19.41%). South Asia (35.47%) and Eastern sub-Saharan Africa (35.24%) were identified as major hotspots. Helminth infections were most commonly caused by Ascaris lumbricoides (11.93%), while Giardia lamblia (10.37%) was the predominant protozoan. Studies using more sensitive diagnostic methods reported substantially higher prevalence. Environmental factors such as tropical savanna climates, moderate rainfall, and high humidity were associated with increased infection rates. Gender differences in prevalence were negligible.
Conclusions
IPIs continue to pose a substantial global health burden on children under five, with socioeconomic and environmental disparities strongly influencing prevalence. The findings highlight the need for targeted public health interventions, including deworming programs, improved sanitation, and clinical surveillance, particularly in high-burden regions. Enhanced diagnostic strategies are essential to accurately capture infection rates and guide effective prevention and treatment efforts.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12889-026-27787-2.
Keywords: Intestinal parasitic infections, Children under five, Prevalence, Child health, Soil-transmitted helminths, Neglected tropical diseases, WASH
Background
Intestinal parasitic infections (IPIs) continue to pose a major threat to public health across the world [1]. These parasites are a major cause of global morbidity and mortality in endemic regions [2]. Intestinal parasites are commonly divided into protozoa and helminths. The data from World Health Organization (WHO) indicate that the soil-transmitted helminths (STHs), including Ascaris lumbricoides, hookworms, and Trichuris trichiura are among the most common parasitic infections globally [3, 4]. Beyond helminth infections, enteric protozoan infections remain a significant public health concern, largely due to their role in causing diarrheal illness in young children. Although diarrhea can result from various pathogens, Entamoeba histolytica, Giardia duodenalis, and Cryptosporidium species have been consistently identified as leading causative agents in pediatric populations worldwide [2, 5].
Children with poor nutritional status are highly vulnerable to IPIs, while persistent parasitic infections can, in turn, aggravate undernutrition, causing a lethal cycle of worsening illness and malnutrition [6, 7]. Together, these factors contribute substantially to high under-five mortality in developing and highly populated nations, with undernutrition accounting for almost 50% of such deaths [6]. In 2020, approximately 45.4 million children under five were affected by wasting, while 149.2 million experienced stunting worldwide. The Southeast Asia region was the most severely impacted, with over 30% of children affected by stunting and more than 15% by wasting during the same year [6, 8]. Although IPIs remain more prevalent in developing countries, incidence is rising in developed nations due to globalization as well, driven by globalization of the food supply, international travel, and migration [9].
In developed countries, migration from less-developed regions can contribute to public health challenges. Therefore, understanding its global prevalence helps facilitate the implementation of tertiary prevention measures, including the diagnosis and treatment of affected individuals [10, 11].
This systematic review and meta-analysis aims to provide a comprehensive assessment of the global prevalence of IPIs in children under five years of age. While numerous studies have examined IPIs at local or national levels, especially in endemic regions, there is limited synthesis of data across countries and continents [12–14]. The novelty of this study stems from its wide global coverage, its emphasis on the highly vulnerable population of children under five years old, and its incorporation of socioeconomic, environmental, and diagnostic factors that affect prevalence. In contrast to earlier research, this study explores geographic hotspots, climate conditions, income levels, and human development indices, providing a comprehensive and multidimensional perspective on the global disease burden.
Methods
Search strategy
This systematic review and meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [15] (Fig. 1 and Supplementary Table 1). A comprehensive search was performed across multiple databases, including PubMed, Web of Science, Scopus, ScienceDirect, and Google Scholar, to identify studies reporting intestinal parasitic infections in children under five years old.
Fig. 1.
Flow diagram of the study design process
Search terms, used individually or in combination with Boolean operators (AND/OR), included: epidemiology, prevalence, incidence, parasites, parasitic diseases, parasitic infections, helminthiasis, helminth parasites, helminthic infections, protozoan infections, protozoan pathogens, intestinal protozoans, preschool-age children, under five years old, young child, infant, global, and worldwide.
Additionally, the search strategy was designed to include literature from the following 19 countries: Bangladesh, Burkina Faso, Cambodia, Egypt, Ethiopia, India, Iran, Iraq, Kenya, Malaysia, Mexico, Mozambique, Nepal, Nigeria, Pakistan, Peru, the Philippines, Rwanda, and Saudi Arabia. After initial screening of titles and abstracts, duplicates and irrelevant studies were removed. The remaining full-text articles were independently reviewed by two authors (Z.G. and F.M.), and reference lists were examined to identify any additional eligible studies not captured in the database search.
Inclusion and exclusion criteria
The following predefined inclusion criteria were applied: (1) peer-reviewed articles presenting original data, (2) published in English before November 2025, (3) cross-sectional studies reporting the prevalence of intestinal parasitic infections in children under five years old in any region of the world, (4) availability of both abstract and full text, and (5) reporting of numerator and denominator data sufficient to calculate prevalence. Studies that did not meet these criteria such as those in other languages, review articles without original data, letters, editorials, or articles with unclear or indeterminate results were excluded.
Data extraction was performed independently by two reviewers (Z.G. and F.M.) using a standardized Excel template, and a third reviewer (A.V.E.) cross-verified the entries to ensure accuracy. Extracted information included: first author, country and specific study location (province/city/district), year of publication, sample size, number of positive cases, participant gender, clinical manifestations, WHO region (African, Americas, South-East Asia, Eastern Mediterranean, Western Pacific), Global Burden of Disease (GBD) region (Andean Latin America, Central Latin America, Eastern sub-Saharan Africa, North Africa and Middle East, South Asia, Southeast Asia, Western sub-Saharan Africa), Human Development Index (HDI) (https://hdr.undp.org/data-center/human-development-index#/indicies/HDI), countries income level (https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-and-lending-groups), types of sample, diagnostic method, and species of parasites.
In addition, climatic variables were recorded for each study region, including humidity (https://www.timeanddate.com/weather/iran/tehran/climate), annual rainfall (https://en.climate-data.org/), average temperature (https://en.climate-data.org/), and climate (https://www.britannica.com/science/Koppen-climate-classification) (Tables 1, 2 and 3).
Table 1.
Main characteristics of the included studies reporting the prevalence of intestinal helminthic and protozoan parasites among children under 5 years old
| Study No | Author | Study Year | Country | District / City / province | Diagnostic method | Sample size | Infected | Species of parasites | Clinical manifestations |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Daniel Gebretsadik et al | 2018 | Ethiopia | Dessie | Direct smear & Concentration (Sedimentation) & staining | 232 | 36 | Entamoeba histolytica, Hymenolepis nana, Giardia lamblia, Schistosoma spp., Enterobius vermicularis | ---- |
| 2 | Getamesay Mulatu et al | 2015 | Ethiopia | Hawassa | Direct smear & Concentration (Sedimentation) & staining | 158 | 42 | Entamoeba histolytica, Giardia lamblia, Cryptosporidium spp., Ascaris lumbricoides, Hymenolepis nana, Trichuris trichiura | ---- |
| 3 | Catrin E. Moore et al | 2015 | Cambodia | Siem Reap | Direct smear & Concentration (Sedimentation) & staining | 318 | 159 | Hookworm, Strongyloides stercoralis, Enterobius vermicularis, Hymenolepis nana, Giardia lamblia, Blastocystis hominis, Entamoeba histolytica, Cryptosporidium spp., Cyclospora cayetanensis | Diarrhea, Abdominal pain, Anemia, Malnutrition |
| 4 | Filipa Santana Ferreira et al | 2019 | Mozambique | Nampula | Direct smear & Concentration (Sedimentation) & staining | 831 | 263 | Giardia lamblia, Strongyloides stercoralis, Cryptosporidium spp., Ascaris lumbricoides, Hookworm, Trichuris trichiura, Entamoeba histolytica, Hymenolepis nana, Cystoisospora belli | Diarrhea, Malnutrition |
| 5 | Evariste Hakizimana et al | 2023 | Rwanda | Nyamasheke | Direct smear & Concentration (Sedimentation) | 1048 | 557 | Ascaris lumbricoides, Trichuris trichiura, Hookworm, Taenia spp., Giardia lamblia, Entamoeba histolytica, Entamoeba coli | ---- |
| 6 | Telanesh Zemene and Melashu Balew Shiferaw | 2018 | Ethiopia | Debre Birhan | Direct smear & Concentration (Sedimentation) | 247 | 43 | Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Trichuris trichiura, Taenia spp. | ---- |
| 7 | Arsène W Zongo et al | 2019 | Burkina Faso | Ouagadougou | Direct smear & staining | 317 | 66 | Entamoeba histolytica, Entamoeba coli, Giardia lamblia, Trichomonas intestinalis, Hymenolepis nana | abdominal pain, vomiting, fever,constipation, anorexia, nausea and diarrhea |
| 8 | Fatemeh Mesgarian et al | 2017 | Iran | Gonbad-e Kavus | Direct smear & Concentration (Sedimentation) & staining | 932 | 248 | Enterobius vermicularis, Blastocystis hominis, Giardia lamblia, Endolimax nana, Dientamoeba fragilis, Entamoeba coli, Iodamoeba buetschlii, Chilomastix mesnili, Trichomonas hominis | ---- |
| 9 | Hossain Haratipour et al | 2016 | Iran | Shahroud | Direct smear & Concentration (Sedimentation) & Scotch Tape Test | 1850 | 649 | Giardia lamblia, Hymenolepis nana, Enterobius vermicularis, Entamoeba Coli, Entamoeba Hartmanni, Dientamoeba Fragilis, Endolimax Nana, Iodamoeba Butschili, Blastocystis Homonis, Chilomastix Mesnili | Malnutrition |
| 10 | Tadesse Duguma et al | 2023 | Ethiopia | Bachuma | Direct smear | 323 | 95 | Ascaris lumbricoides, Trichuris trichiura, Giardia lamblia, Schistosoma.spp, Hymenolepis nana, Entamoeba histolytica, Hook worm | ---- |
| 11 | Greisi Curico et al | 2022 | Peru | Iquitos | Direct smear & Concentration (Sedimentation) & PCR | 144 | 16 | Strongyloides stercoralis, Trichuris trichiura, Ascaris lumbricoides, Hook worm, Ascaris lumbricoides | ---- |
| 12 | Kristen Aiemjoy et al | 2017 | Ethiopia | Amhara | Direct smear & Concentration (Sedimentation) | 212 | 138 | Ascaris lumbricoides, Trichuris trichiura, Giardia lamblia, Entamoeba histolytica, Entamoeba coli, Blastocystis hominis, Iodamoeba butschlii, Endolimax nana, Entamoeba hartmanni | Diarrhea, Stunting, Underweight |
| 13 | Javier Gutiérrez-Jiménez et al | 2018 | Mexico | Chiapas | Direct smear & Concentration (Sedimentation) | 178 | 60 | Trichuris trichiura, Hymenolepis nana, Enterobius vermicularis, Entamoeba histolytica, Giardia lamblia | malnutrition, Underweight, Stunted |
| 14 | Adham Mohammad Hegazy et al | 2014 | Egypt | Damanhur | Direct smear & staining & kato-katz method | 500 | 259 | Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Enterobius vermicularis, Hook worm, Hymenolepis nana | Abdominal Colic, Constipation, Diarrhea, Vomiting, Fatigue, Peri anal itching, Pallor |
| 15 | Amanuel Yosep and Hunachew Beyene | 2020 | Ethiopia | Boricha Woreda | Direct smear & staining & kato-katz method | 622 | 303 | Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides, Trichuris trichiura, Hook worm, Taenia spp., Strongyloides stercoralis | ---- |
| 16 | Muhammad Faisal Afridi et al | 2020 | Pakistan | Skardu | Direct smear & staining | 300 | 161 | Ascaris Lumbricoides, Hymenolepis Nana, Cryptosporidium spp., Giardia lamblia | ---- |
| 17 | S. Awasthi and V.K. Pande | 1997 | India | Lucknow | Direct smear & staining | 1061 | 185 | Ascaris lumbricoides, Giardia lamblia | Malnutrition, low hemoglobin levels |
| 18 | Ralf Ignatius et al | 2012 | Rwanda | Butare | Direct smear & Concentration (Sedimentation) & PCR | 582 | 233 | Ascaris lumbricoides, Giardia lamblia, Cryptosporidium spp., Hook worm, Entamoeba histolytica, Trichuris trichiura, Strongyloides stercoralis, Balantidium coli, Entamoeba coli, Blastocystis hominis, Iodamoeba buetschlii, Trichomonas hominis, Endolimax nana, Chilomastix mesnili | Abdominal distension |
| 19 | SM Sadjjadi and N Tanideh | 2005 | Iran | Marvdasht | Direct smear & Concentration (Sedimentation) | 337 | 115 | Giardia lamblia, Entamoeba histolytica, Blastocystis hominis, Hymenolepis nana, Chilomastix mesnili, Ascaris lumbricoides, Trichuris trichiura, Iodamoeba buetschlii, Enterobius vermicularis | Stunting, underweight, wasting |
| 20 | Parminder S. Suchdev et al | 2014 | Kenya | Kibera | Direct smear & Elisa | 205 | 120 | Ascaris lumbricoides, Trichuris trichiura, Malaria spp. | Anemia, Low ferritin, Underweight |
| 21 | Zulkifli A et al | 1999 | Malaysia | Kelantan | Direct smear & staining | 268 | 127 | Ascaris lumbricoides, Trichuris trichiura, Hook worm | Stunting, underweight, wasting |
| 22 | O. O. Omitola et al | 2016 | Nigeria | Ogun | Direct smear & Concentration (Sedimentation) | 97 | 50 | Ascaris lumbricoides, Hook worm | Stunting, underweight, wasting, thinness |
| 23 | A. Desiree LaBeaud et al | 2015 | Kenya | Msambweni | Direct smear & Concentration (Sedimentation) & PCR | 545 | 216 | Ascaris lumbricoides, Malaria, Filaria, Schistosoma spp. | ---- |
| 24 | Md. Shabab Hossain et al | 2019 | Bangladesh | Dhaka | Direct smear & Elisa | 240 | 134 | Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Giardia lamblia, Cryptosporidium spp., Iodamoeba buetschlii | Anemia |
| 25 | Al-Daoody and Al-Bazzaz | 2020 | Iraq | Erbil | Direct smear & Concentration (Sedimentation) & Scotch Tape Test | 237 | 65 | Enterobius vermicularis | ---- |
| 26 | Nagwa S.M. Aly et al | 2010 | Saudi Arabia | Tabuk | Direct smear & Concentration (Sedimentation) & staining | 64 | 4 | Entameoba histolytica, Giardia lamblia, Cryptosporidium spp., Hymenolepis Nana, Ascaris lumbricoides, Entrobius vermicularis | ---- |
| 27 | Dhiren Subba Limbu et al | 2021 | Nepal | Dharan | Direct smear & Concentration (Sedimentation) | 116 | 9 | Entamoeba histolytica, Hymenolepis nana, Giardia lamblia, Hookworm, Entamoeba coli, Ascaris lumbricoides | ---- |
| 28 | P Pradhan et al | 2013 | Nepal | Kathmandu | Direct smear | 26 | 11 | Entamoeba histolytica, Hymenolepis nana, Giardia lamblia, Trichuris trichiura, Hook worm | ---- |
| 29 | M.H Anvari Tafti et al | 2014 | Iran | Yazd | Direct smear & Concentration (Sedimentation) | 180 | 18 | Giardia lamblia, Blastocystis hominis, Chilomastix mesnili, Entamoeba Coli, Dientamoeba fragilis | underweight |
| 30 | Bong-Jin KIM et al | 2003 | Philippines | Roxas | Direct smear & Concentration (Sedimentation) | 301 | 35 | Ascaris lumbricoides, Trichuris trichiura, Hook worm, Entamoeba Coli | ---- |
| 31 | Sachita Dhital et al | 2016 | Nepal | Kathmandu | Direct smear & Concentration (Sedimentation) & staining | 238 | 78 | Entameoba histolytica, Giardia lamblia, Ascaris lumbricoides, Hymenolepis nana, Trichuris trichiura, Schistosoma spp., Blastocystis hominis, Cryptosporidium spp., Entamoeba Coli | ---- |
| 32 | Harith Saeed Jaeffer | 2011 | Iraq | Baghdad | Direct smear & Concentration (Sedimentation) | 513 | 53 | Entameoba histolytica, Giardia lamblia | Diarrhea |
| 33 | Upama KC et al | 2019 | Nepal | Kathmandu | Direct smear & Concentration (Sedimentation) | 20 | 16 | Ascaris lumbricoides, Trichuris trichiura, Hook worm, Hymenolepis nana, Entameoba histolytica, Giardia lamblia, Blastocystis hominis, Entamoeba Coli, Entamoeba hartmanni, Endolimax nana | ---- |
| 34 | Daniel Njenga et al | 2022 | Kenya | Nairobi | Direct smear & staining & kato-katz method | 406 | 110 | Ascaris lumbricoides, Trichuris trichiura, Hook worm, Entameoba histolytica, Giardia lamblia, Entamoeba Coli | ---- |
| 35 | Bhattachan B et al | 2015 | Nepal | Chitwan | Direct smear & Concentration (Sedimentation) | 63 | 17 | Giardia lamblia, Blastocystis hominis, Entamoeba Coli, Entameoba histolytica, Endolimax nana, Taenia spp., Hymenolepis nana, Trichuris trichiura, Hook worm | ---- |
| 36 | Showkat Ahmad Wani et al | 2010 | India | Kashmir | Direct smear & Concentration (Sedimentation) & Scotch Tape Test | 91 | 46 | Ascaris lumbricoides, Trichuris trichiura, Taenia spp., Entrobius vermicularis | ---- |
| 37 | Rashid MK et al | 2011 | India | Bareilly | Direct smear | 53 | 11 | Ascaris lumbricoides, Giardia lamblia, Entameoba histolytica, Hymenolepis nana, Trichuris trichiura, Taenia spp. | itching |
| 38 | Khadejeh Salahi et al | 2019 | Iran | Zanjan | Direct smear & Concentration (Sedimentation) & Scotch Tape Test | 137 | 9 | Giardia lamblia, Blastocystis hominis, Entamoeba Coli, Endolimax nana, Taenia spp., Entrobius vermicularis | ---- |
| 39 | Amulya Dahal et al | 2022 | Nepal | Kirtipur | Direct smear | 76 | 17 | Ascaris lumbricoides, Trichuris trichiura, Hook worm, Hymenolepis nana, Taenia spp., Entrobius vermicularis, Giardia lamblia, Entameoba histolytica | ---- |
| 40 | Rawaa Abdulkhaleq Hussein et al | 2011 | Iraq | Baghdad | Direct smear & Concentration (Sedimentation) | 285 | 134 | Giardia lamblia, Entameoba histolytica, Entamoeba Coli, Endolimax nana, Iodamoeba buetschlii, Blastocystis hominis, Ascaris lumbricoides, Hymenolepis nana, Taenia spp., Entrobius vermicularis | Abdominal pain, Diarrhea, Fever, Vomiting, Perianal pruritus, Bloody diarrhea, Rectal prolaps |
| 41 | Degu Abate et al | 2025 | Ethiopia | Shinile | Direct smear & staining | 756 | 115 | Cryptosporidium spp. | Diarrhea |
Table 2.
Sub–group analysis based on HDI, income level, types of sample, diagnostic method, average temperature, annual rainfall, climate, GBD geographic regions, WHO region, countries, humidity, gender and district/city/province in included studies
| Variables | No studies | Sample size | Infected |
Pooled prevalence
(95% CI) |
Heterogeneity |
|---|---|---|---|---|---|
| I2 τ2 p- value | |||||
| HDI | |||||
| Very High human development | 3 | 476 | 147 | 19.41 (2.15–47.33) | 97 6.78 P < .001 |
| High human development | 8 | 4415 | 1393 | 24.81 (14.54–36.76) | 97 3.4 P < .001 |
| Medium human development | 17 | 4493 | 1381 | 34.60 (25.58–44.20) | 97 3.94 P < .001 |
| Low human development | 13 | 5725 | 2102 | 35.17 (26.07–44.84) | 98 3.2 P < .001 |
| Income Level | |||||
| High income level | 1 | 64 | 4 | 6.25 (2.94–15.38) | - - - |
| Upper middle income level | 11 | 5061 | 1494 | 24.95 (16.43–34.58) | 97 3.06 P < .001 |
| Lower middle income level | 18 | 4656 | 1634 | 37.45 (28.44–46.90) | 97 3.97 P < .001 |
| Low income level | 11 | 5328 | 1891 | 32.23 (22.77–42.49) | 98 3.14 P < .001 |
| Types of sample | |||||
| Stool | 35 | 12,321 | 4044 | 29.99 (24.04–36.29) | 97 3.84 P < .001 |
| Stool & Blood | 6 | 2788 | 979 | 41.08 (27.72–55.14) | 98 3.02 P < .001 |
| Diagnostic method | |||||
| Direct smear | 4 | 478 | 134 | 27.26 (18.99–36.37) | 43 0.59 P = .15 |
| Direct smear & staining | 5 | 2702 | 654 | 29.68 (15.38–46.38) | 98 3.81 P < .001 |
| Direct smear & Concentration (Sedimentation) | 13 | 3597 | 1245 | 32.10 (19.87–45.70) | 98 6.29 P < .001 |
| Direct smear & Concentration (Sedimentation) & staining | 7 | 2773 | 830 | 26.36 (16.57–37.48) | 94 2.46 P < .001 |
| Direct smear & Concentration (Sedimentation) & Scotch Tape Test | 4 | 2315 | 769 | 28.11 (11.34–48.79) | 96 4.59 P < .001 |
| Direct smear & Concentration (Sedimentation) & PCR | 3 | 1271 | 465 | 29.30 (11.89–50.60) | 96 3.65 P < .001 |
| Direct smear & staining & Kato-katz method | 3 | 1528 | 672 | 42.34 (27.45–57.93) | 97 1.86 P < .001 |
| Direct smear & ELISA | 2 | 445 | 254 | 57.09 (52.34–61.77) | 0 < .0001 P = .57 |
| Average temperature | |||||
| 10_20 | 11 | 3975 | 1187 | 26.84 (15.9–39.37) | 94 4.66 P < .001 |
| > 20 | 30 | 11,134 | 3836 | 33.37 (27.06–40) | 97 3.55 P < .001 |
| Annual rainfall | |||||
| < 400 | 10 | 5035 | 1554 | 23.94 (14.19–35.28) | 97 3.9 P < .001 |
| 400–1000 | 15 | 6050 | 2285 | 36.65 (28.10–45.64) | 97 3.16 P < .001 |
| 1001–1500 | 10 | 1084 | 524 | 33.60 (20.78–47.74) | 95 4.87 P < .001 |
| > 1500 | 6 | 2040 | 660 | 29.68 (16.77–44.47) | 97 3.57 P < .001 |
| Climate | |||||
| Desert climate | 14 | 4627 | 1508 | 30.71 (21.25–41.07) | 98 4.12 P < .001 |
| Semi-desert climate | 6 | 3753 | 1105 | 21.30 (12.21–32.09) | 96 2.24 P < .001 |
| Tropical monsoon climate | 8 | 954 | 357 | 37.20 (22.14–53.60) | 94 5.09 P < .001 |
| Tropical rainforest climate | 3 | 713 | 178 | 21.61 (4.41–46.80) | 98 5.52 P < .001 |
| Tropical savanna climate | 6 | 3617 | 1499 | 41.38 (31.90–51.19) | 96 1.46 P < .001 |
| Tropical wet-dry climate | 4 | 1445 | 376 | 35.24 (17.12–55.86) | 98 4.24 P < .001 |
| GBD geographic regions | |||||
| Andean Latin America | 1 | 144 | 16 | 11.11 (7.07–17.37) | - - - |
| Central Latin America | 1 | 178 | 60 | 33.71 (27.16–40.92) | - - - |
| Eastern sub-Saharan Africa | 13 | 6167 | 2271 | 35.24 (26.41–44.61) | 97 3.02 P < .001 |
| North Africa and Middle East | 10 | 5035 | 1554 | 23.94 (14.19–35.28) | 97 3.9 P < .001 |
| South Asia | 11 | 2284 | 685 | 35.47 (23.18–48.78) | 96 4.73 P < .001 |
| Southeast Asia | 3 | 887 | 321 | 34.80 (12.02–62.09) | 98 5.84 P < .001 |
| Western sub-Saharan Africa | 2 | 414 | 116 | 35.09 (9.65–66.25) | 96 4.99 P < .001 |
| WHO region | |||||
| African | 15 | 6581 | 2387 | 35.20 (27.03–43.82) | 97 2.94 P < .001 |
| Americas | 2 | 322 | 76 | 21.38 (4.35–46.33) | 95 3.53 P < .001 |
| Eastern Mediterranean | 11 | 5335 | 1715 | 26.39 (16.15–38.10) | 97 4.38 P < .001 |
| South-East Asia | 10 | 1984 | 524 | 33.60 (20.78–47.74) | 95 4.87 P < .001 |
| Western Pacific | 3 | 887 | 321 | 34.80 (12.02–62.09) | 98 5.84 P < .001 |
| Countries | |||||
| Bangladesh | 1 | 240 | 134 | 5.58 (4.95–6.19) | - - - |
| Burkina Faso | 1 | 317 | 66 | 20.82 (16.61–25.55) | - - - |
| Cambodia | 1 | 318 | 159 | 50 (44.54–55.46) | - - - |
| Egypt | 1 | 500 | 259 | 51.80 (47.43–56.14) | - - - |
| Ethiopia | 7 | 2550 | 772 | 30.06 (17.26–44.66) | 98 4.07 P < .001 |
| India | 3 | 1205 | 242 | 28.49 (11.14–49.90) | 95 3.50 P < .001 |
| Iran | 5 | 3436 | 1039 | 21.34 (10.48–34.74) | 96 2.82 P < .001 |
| Iraq | 3 | 1035 | 252 | 26.79 (8.80–50.07) | 98 4.47 P < .001 |
| Kenya | 3 | 1156 | 446 | 41.34 (24.37–59.44) | 96 2.49 P < .001 |
| Malaysia | 1 | 268 | 127 | 47.39 (41.39–53.40) | - - - |
| Mexico | 1 | 178 | 60 | 33.71 (27.11–40.90) | - - - |
| Mozambique | 1 | 831 | 263 | 31.65 (27.80–34.34) | - - - |
| Nepal | 6 | 539 | 148 | 32.73 (14.72–53.72) | 92 6.31 P < .001 |
| Nigeria | 1 | 97 | 50 | 51.55 (41.69–61.30) | - - - |
| Pakistan | 1 | 300 | 161 | 53.76 (48–59.30) | - - - |
| Peru | 1 | 144 | 16 | 11.11 (6.47–16.91) | - - - |
| Philippines | 1 | 301 | 35 | 11.63 (8.32–15.61) | - - - |
| Rwanda | 2 | 1630 | 790 | 46.64 (34.21–59.28) | 96 0.80 P < .001 |
| Saudi Arabia | 1 | 64 | 4 | 6.25 (3.08–15.48) | - - - |
| Humidity | |||||
| < 40 | 7 | 5066 | 1829 | 28.04 (13.46–45.47) | 98 3.77 P < .001 |
| 40–75 | 30 | 8953 | 2732 | 32.04 (25.09–39.41) | 97 4.00 P < .001 |
| > 75 | 4 | 1090 | 462 | 34.99 (8.83–67.40) | 97 4.12 P < .001 |
| Gender | |||||
| Male | 17 | 8559 | 1602 | 33.10 (25.34–41.34) | 95 2.98 P < .001 |
| Female | 17 | 4272 | 1551 | 33.19 (25.34–41.54) | 94 3.05 P < .001 |
| District/City/province | |||||
| Amhara | 1 | 212 | 138 | 65.09 (58.46–71.18) | - - - |
| Bachuma | 1 | 323 | 95 | 29.41 (24.63–34.55) | - - - |
| Baghdad | 2 | 798 | 187 | 26.51 (1.41–67.03) | 99 8.99 P < .001 |
| Bareilly | 1 | 53 | 11 | 20.75 (12.66–33.75) | - - - |
| Boricha Woreda | 1 | 622 | 303 | 48.71 (44.79–52.64) | - - - |
| Butare | 1 | 582 | 233 | 40.03 (36.11–44.06) | - - - |
| Chiapas | 1 | 178 | 60 | 33.71 (27.28–40.97) | - - - |
| Chitwan | 1 | 63 | 17 | 26.98 (18.07–39.19) | - - - |
| Damanhur | 1 | 500 | 259 | 51.80 (47.42–56.16) | - - - |
| Debre Birhan | 1 | 247 | 43 | 17.41 (13.08–22.55) | - - - |
| Dessie | 1 | 232 | 36 | 15.52 (11.41–20.72) | - - - |
| Dhaka | 1 | 240 | 134 | 55.83 (49.51–61.99) | - - - |
| Dharan | 1 | 116 | 9 | 7.76 (4.43–14.32) | - - - |
| Erbil | 1 | 237 | 65 | 27.43 (22.21–33.48) | - - - |
| Gonbad-e Kavus | 1 | 932 | 248 | 26.61 (23.81–29.49) | - - - |
| Hawassa | 1 | 158 | 42 | 26.58 (20.47–34.05) | - - - |
| Iquitos | 1 | 144 | 16 | 11.11 (7.18–17.46) | - - - |
| Kashmir | 1 | 91 | 46 | 50.55 (40.54–60.51) | - - - |
| Kathmandu | 3 | 284 | 105 | 50.51 (23.21–77.65) | 88 5.33 P < .001 |
| Kelantan | 1 | 268 | 127 | 47.39 (41.51–53.35) | - - - |
| Kibera | 1 | 200 | 120 | 58.54 (51.69–65.05) | - - - |
| Kirtipur | 1 | 76 | 17 | 22.37 (14.77–33.08) | - - - |
| Lucknow | 1 | 1061 | 185 | 17.44 (14.77–19.40) | - - - |
| Marvdasht | 1 | 337 | 115 | 34.12 (29.15–39.28) | - - - |
| Msambweni | 1 | 545 | 216 | 39.63 (35.10–43.58) | - - - |
| Nairobi | 1 | 406 | 110 | 27.09 (22.92–31.56) | - - - |
| Nampula | 1 | 831 | 263 | 31.65 (28.53–34.86) | - - - |
| Nyamasheke | 1 | 1048 | 557 | 53.15 (50.12–56.17) | - - - |
| Ogun | 1 | 97 | 50 | 51.55 (41.80–61.15) | - - - |
| Ouagadougou | 1 | 317 | 66 | 20.82 (15.23–24.53) | - - - |
| Roxas | 1 | 301 | 35 | 11.63 (8.52–15.77) | - - - |
| Shahroud | 1 | 1850 | 649 | 35.08 (32.68–37.09) | - - - |
| Shinile | 1 | 756 | 115 | 15.21 (12.47–17.64) | - - - |
| Siem Reap | 1 | 318 | 159 | 50 (44.45–55.55) | - - - |
| Skardu | 1 | 300 | 161 | 53.67 (48.01–59.26) | - - - |
| Tabuk | 1 | 64 | 4 | 6.25 (2.56–15.08) | - - - |
| Yazd | 1 | 180 | 18 | 10 (6.51–15.32) | - - - |
| Zanjan | 1 | 137 | 9 | 6.57 (3.76–12.24) | - - - |
| Total | 41 | ||||
Table 3.
Sub-group analysis based on type of helminthic and protozoan parasites
| Type of parasite | No studies | Sample size | Infected |
Pooled prevalence
(95% CI) |
Heterogeneity |
|---|---|---|---|---|---|
|
I
2
τ2 p -value | |||||
| Protozoan | |||||
| Giardia lamblia | 23 | 11,423 | 1236 | 10.37 (7.80–13.26) | 95 1.06 P < .001 |
| Blastocystis hominis | 8 | 4696 | 169 | 3.95 (1.52–7.42) | 96 1.09 P < .001 |
| Cyclospora cayetanensis | 1 | 318 | 9 | 2.83 (1.47–5.26) | - - - |
| Chilomastix mesnili | 5 | 3881 | 27 | 0.88 (0.13–2.15) | 89 0.29 P < .001 |
| Cryptosporidium spp. | 7 | 3116 | 239 | 6.25 (3.03–10.47) | 94 0.95 P < .001 |
| Dientamoeba fragilis | 3 | 2962 | 21 | 0.84 (0–2.76) | 94 0.36 P < .001 |
| Entamoeba coli | 11 | 6229 | 519 | 6.56 (2.16–13.03) | 98 3.34 P < .001 |
| Entamoeba hartmanni | 2 | 2062 | 6 | 0.50 (0–2.34) | 81 0.26 P < .001 |
| Entamoeba histolytica/dispar | 16 | 6576 | 467 | 5.99 (3.63–8.86) | 95 1.13 P < .001 |
| Endolimax nana | 5 | 3861 | 118 | 4.55 (0.43–12.44) | 96 2.65 P < .001 |
| Iodamoeba buetschlii | 7 | 4463 | 56 | 1.38 (0.24–3.30) | 90 0.66 P < .001 |
| Balantidium coli | 1 | 582 | 1 | 0.17 (0–0.08) | - - - |
| Helminth | |||||
| Ascaris lumbricoides | 20 | 8551 | 1112 | 11.93 (7.42–17.33) | 97 2.93 P < .001 |
| Hymenolepis nana/diminuta | 10 | 5038 | 81 | 1.69 (0.58–3.29) | 89 0.58 P < .001 |
| Hookworm | 12 | 5412 | 182 | 3.20 (1.59–5.33) | 91 0.76 P < .001 |
| Strongyloides stercoralis | 4 | 2353 | 78 | 3.23 (0.67–7.51) | 94 0.91 P < .001 |
| Schistosoma spp. | 2 | 868 | 28 | 3.21 (2.08–4.57) | 0 0.01 P = .051 |
| Trichomonas hominis | 3 | 1831 | 31 | 1.76 (0.08–5.25) | 94 0.68 P < .001 |
| Trichuris trichiura | 14 | 5825 | 288 | 4.52 (2.19–7.60) | 94 1.42 P < .001 |
| Enterobius vermicularis | 9 | 4902 | 473 | 4.70 (0.99–10.80) | 97 3.03 P < .001 |
| Taenia spp. | 4 | 2202 | 26 | 1.08 (0.60–1.68) | 0 0.02 P < .001 |
Data synthesis and statistical analysis
Various statistical methods were employed to comprehensively evaluate the global prevalence of intestinal parasitic infections in children under five years old. The overall pooled prevalence was calculated with a 95% confidence interval (CI). A random-effects model using the Freeman-Tukey double arcsine transformation was applied to estimate the pooled prevalence. Publication bias was assessed using Egger’s funnel plot, Begg’s rank correlation test, the Luis Furuya-Kanamori (LFK) index, and the Doi plot [14]. An LFK index beyond ± 2 was considered indicative of major asymmetry, values between ± 1 and ± 2 indicated minor asymmetry, and values within ± 1 were interpreted as symmetry, suggesting no evidence of publication bias.
Heterogeneity across the included studies was assessed using Cochrane’s Q test and quantified with the I2 statistic, with I2 values interpreted according to established thresholds: 0–25% indicated low heterogeneity, 25–50% moderate heterogeneity, and 50–75% high heterogeneity, in line with current methodological recommendations [16]. A p-value < 0.05 was considered statistically significant. All analyses were conducted using the meta and metasens packages in R (version 3.6.1) [17].
Study quality assessment
A modified version of the Newcastle–Ottawa Scale was used to assign a quality score. This score evaluated the appropriateness of the study design, recruitment strategy, response rate, representativeness of the sample, objectivity and reliability of outcome assessment, provision of a power calculation, and suitability of the statistical analyses. Any discrepancies in scoring were resolved through consensus, resulting in a final agreed-upon rating for each study [18]. Studies were rated across three domains: selection (5 stars max), comparability (2 stars max), and outcome (3 stars max) Supplementary Table 2.
Results
Based on the data from 41 studies included in this review indicates that the combined global prevalence of intestinal parasitic infections among children under five is 31.60% (95% CI: 26.04–37.44) (Fig. 2). The data highlight a pronounced socioeconomic divide, with the greatest burden observed in regions with constrained economic development. Children in lower-middle-income countries exhibited the highest prevalence at 37.45% (95% CI: 28.44–46.90), followed by those in low-income countries at 32.23% (95% CI: 22.77–42.49). In comparison, high-income countries showed a significantly reduced prevalence of 6.25% (95% CI: 2.94–15.38). Findings from HDI-based subgroup analyses reinforce this trend, demonstrating a strong negative correlation between a country's human development level and the prevalence of intestinal parasitic infections in young children.
Fig. 2.
Forest plots for random-effects meta-analysis of intestinal parasitic infection in children under five years old (The boxes indicate the effect size of the studies (prevalence) and the whiskers indicate its confidence interval for corresponding effect size. There is no specific difference between white and black bars, only studies with a very narrow confidence interval are shown in white. In the case of diamonds, their size indicates the size of the effect, and their length indicates confidence intervals)
The greatest burden of infection was found in countries with low HDI, where the prevalence reached 35.17% (95% CI: 26.07–44.84), followed closely by medium HDI nations at 34.60% (95% CI: 25.58–44.20). In contrast, prevalence declined steadily with higher levels of development. Countries classified as high HDI showed a substantially lower prevalence of 24.81% (95% CI: 14.54–36.76), and those with very high HDI reported the lowest rates at 19.41% (95% CI: 2.15–47.33).
The diagnostic approach used in the studies played a major role in determining the estimated prevalence of infection. Research employing more sensitive methods, specifically the combination of direct smear with enzyme-linked immunosorbent assay (ELISA) reported the highest pooled prevalence at 57.09% (95% CI: 52.34–61.77). Similarly, studies utilizing direct smear alongside staining techniques and the Kato-Katz method also identified a relatively high prevalence of 42.34% (95% CI: 27.45–57.93).
According to the GBD regional classification, the greatest prevalence of intestinal parasitic infections among children under five occurred in South Asia (35.47%, 95% CI: 23.18–48.78), based on 11 studies, and Eastern sub-Saharan Africa (35.24%, 95% CI: 26.41–44.61), based on 13 studies. In contrast, Andean Latin America reported the lowest prevalence at 11.11% (95% CI: 7.07–17.37), which included one study.
A similar trend was observed when using the broader WHO regional framework: The African Region (35.20%, 95% CI: 27.03–43.82), which includes Eastern sub-Saharan Africa, showed the highest infection burden, whereas the Region of the Americas (21.38%, 95% CI: 4.35–46.33) exhibited the lowest. These findings highlight significant geographic inequalities, with children in South Asia and Africa experiencing the highest risk of infection.
Country-level findings reveal pronounced disparities in the prevalence of intestinal parasitic infections. Extremely high rates were observed in Pakistan (53.76%, 95% CI: 48.01–59.30), Egypt (51.80%, 95% CI: 47.43–56.14), Nigeria (51.55%, 95% CI: 41.69–61.30), and Cambodia (50.0%, 95% CI: 44.54–55.46), indicating that roughly one in every two children under five is affected in these settings. Climatic conditions also played a critical role in shaping transmission patterns. The tropical savanna climate showed the highest infection prevalence at 41.38% (95% CI: 31.90–51.19), and regions with moderate annual rainfall (400–1000 mm) exhibited the most favorable conditions for parasite spread, with a prevalence of 36.65% (95% CI: 28.10–45.64). In contrast, semi-desert climates (21.30%, 95% CI: 12.21–32.09) and areas receiving low rainfall (< 400 mm) (23.94%, 95% CI: 14.19–35.28) had the lowest infection rates, highlighting the strong dependence of parasite survival and transmission on adequate moisture and temperature.
The subgroup analysis by humidity revealed a distinct environmental pattern: regions with high atmospheric moisture (> 75%) showed the greatest pooled prevalence of intestinal parasitic infections at 34.99% (95% CI: 8.83–67.40). This was followed by areas with moderate humidity (40–75%), where the prevalence reached 32.04% (95% CI: 25.09–39.41). In contrast, locations characterized by low humidity (< 40%) exhibited the lowest prevalence at 28.04% (95% CI: 13.46–45.47). These findings underscore that higher humidity levels serve as an important ecological factor contributing to increased transmission and infection rates.
Similarly, the subgroup analysis stratified by gender indicated minimal variation between males and females: the pooled prevalence was 33.10% (95% CI: 25.34–41.34) among males and 33.19% (95% CI: 25.34–41.54) among females, suggesting that infection burden is essentially comparable across sexes.
The district-, city-, and province-level analysis revealed substantial geographical heterogeneity in the prevalence of intestinal parasitic infections, identifying distinct high-burden areas. The most severe prevalence was observed in Amhara, Ethiopia, where infection rates reached 65.09% (95% CI: 58.46–71.18), indicating that nearly two-thirds of children were affected. This was followed by notably high rates in Kibera, Kenya (58.54%, 95% CI: 51.69–65.05) and Skardu, Pakistan (53.67%, 95% CI: 48.01–59.26). Conversely, the lowest prevalence estimates were recorded in Tabuk, Saudi Arabia (6.25%, 95% CI: 2.56–15.08), with similarly low levels in Zanjan, Iran (6.57%, 95% CI: 3.76–12.24), and Dharan, Nepal (7.76%, 95% CI: 4.43–14.32). The species-specific analysis revealed notable differences in the distribution of intestinal parasites. Among helminths, A. lumbricoides exhibited the highest prevalence at 11.93% (95% CI: 7.42–17.33), whereas Taenia spp. showed the lowest prevalence at 1.08% (95% CI: 0.60–1.68). In terms of protozoan infections, G. lamblia emerged as the most prevalent species with a pooled estimate of 10.37% (95% CI: 7.80–13.26), while Balantidium coli had the lowest prevalence at 0.17% (95% CI: 0.00–0.08).
Based on included studies the global distribution of intestinal parasites in children under five was visualized using QGIS3 software (https://qgis.org/en/site/) (Fig. 3A). Furthermore, the analysis of study distribution using a Sankey diagram (Fig. 3B), the African region was identified as the most prevalent WHO region, with Ethiopia being the most studies country.
Fig. 3.
The global prevalence of intestinal parasitic infection in children under five years old in different geographical regions of the world based on included studies (https://qgis.org/en/site/) (A). Additionally, the Sankey plot presents data concerning the majority of studies related to countries and WHO Region based on the included studies (B)
Meta regression
Meta-regression showed no significant association between year of publication and effect size (slope = 1.207, P = 0.860), indicating that publication year did not explain the between-study heterogeneity (Fig. 4).
Fig. 4.
The global prevalence of intestinal parasitic infections among children under five years old in different geographical regions of the world based on year of publication (the pink line is the regression line, which was plotted based on the intercept and the slope of the regression model). The different coloured bubbles represent the countries under study, and their sizes indicate the effect size of each study
Publication bias
There was no evidence of publication bias. Egger’s test (Z = 0.49, P = 0.621) and Begg’s test (t = 0.31, P = 0.761) were non-significant, and the Doi plot demonstrated no notable asymmetry (LFK index = 0.44), indicating the absence of small-study effects (Fig. 5 A-C).
Fig. 5.
To evaluate potential publication bias in the estimated global prevalence of intestinal parasitic infections among children under five years old, Egger's funnel plot (A) and Begg's plot (B) were generated. In these plots, which use colored circles to represent individual studies, the effect size is marked by a central line, flanked by its confidence intervals. Furthermore, the Doi plot (C) provided a quantitative measure, with a Luis Furuya-Kanamori (LFK) index of 0.44, confirming the absence of significant asymmetry
Quality assessment
Based on the quality assessment, 24 studies were high quality (scores 7–9) and 17 were of moderate quality (scores 4–6) (Supplementary Table 2).
Discussion
This systematic review and meta-analysis provides an important and timely overview of the global impact of IPIs among children under five years of age. The estimated pooled prevalence underscores that IPIs continue to pose a widespread and serious public health concern, disproportionately affecting young children who are among the most vulnerable worldwide. The findings suggest that nearly one in three children in this age group is infected with at least one intestinal parasite, carrying significant consequences for early growth, cognitive development, and overall survival.
A key outcome of this review is the unmistakable socioeconomic divide in the distribution of IPIs. The highest burden falls on children in low- and lower-middle-income countries, whereas rates in high-income settings are substantially lower. This pattern is further supported by the strong negative association with the Human Development Index (HDI), with nations scoring lowest on the HDI experiencing the greatest prevalence. Such disparities are not random; they are fundamentally driven by unequal access to critical resources, including safe water, improved sanitation, suitable living conditions, and adequate healthcare systems [9, 19–21].
Poverty fosters environments in which fecal–oral transmission of intestinal parasites can easily occur. Moreover, these results clearly demonstrate the “vicious cycle” outlined earlier: IPIs lead to malnutrition through diarrhea, impaired nutrient absorption, and nutrient depletion, while malnourished children, whose immune defenses are weakened, become even more vulnerable to recurrent and severe parasitic infections [6, 7, 22]. Our results confirm that this cycle is a significant driver of childhood morbidity and a key obstacle to reducing under five mortality in developing regions.
Geographically, the findings identify South Asia and Eastern sub-Saharan Africa as having the highest burden of intestinal parasitic infections, which corresponds closely with worldwide patterns observed for other poverty-associated neglected tropical diseases and diarrheal conditions [8, 23]. The country-level analysis further highlights Pakistan, Egypt, Nigeria, and Cambodia as critical settings where approximately every second child under five is infected. This level of detail is crucial for directing international aid and national public health resources to where they are most urgently needed. Environmental drivers of transmission were clearly elucidated in our sub-group analyses. The tropical savanna climate, characterized by warm temperatures and seasonal rainfall, demonstrated the highest infection rate. Moderate annual rainfall (400–1000 mm) was the most conducive for transmission, as it provides the necessary moisture for egg and cyst maturation and survival in the soil without washing them away [9, 24, 25]. Correspondingly, high humidity (> 75%) was associated with a higher pooled prevalence. These conditions are ideal for the development and environmental survival of geohelminths like A. lumbricoides and T. trichiura, as well as for the prolonged viability of protozoan cysts [18, 24, 25]. Conversely, the significantly lower prevalence in semi-desert climates and areas with low annual rainfall (< 400 mm) underscores the environmental constraints on parasite survival outside the human host.
These findings carry distinct public health implications that shift away from universal mass drug administration (MDA) toward ecologically-informed intervention strategies. The identification of the 400–1000 mm rainfall belt as a high-transmission zone suggests that resources for MDA and sanitation infrastructure should be prioritized in these isohyetic zones, particularly in sub-Saharan Africa and parts of South America where tropical savannas predominate [26]. Furthermore, in high-transmission zones, water, sanitation, and hygiene (WASH) interventions must move beyond basic latrine construction to include drainage management. Reducing standing water and lowering household-level humidity through improved ventilation and flooring (e.g., replacing earthen floors with concrete) can break the environmental lifecycle of these parasites at the household unit [27].
A critical methodological insight from this review is the substantial influence of diagnostic sensitivity on reported prevalence estimates. Studies using a combination of Direct smear and ELISA demonstrated considerably higher prevalence rates compared to the overall pooled estimate, highlighting how diagnostic choice can affect observed burden. However, this finding should be interpreted cautiously, as it represents an inference derived from subgroup comparisons rather than a direct measurement of the true infection burden. Nevertheless, it provides indirect evidence suggesting that infections such as G. lamblia and Cryptosporidium spp. may be underdetected in field settings that rely primarily on less sensitive, single-method microscopy [5, 14, 28, 29]. The Kato-Katz method, while the gold standard for soil-transmitted helminths, misses protozoans entirely [30]. Therefore, our findings advocate for the use of more sensitive, multiplex diagnostic approaches in future epidemiological surveys to capture the true scale of the problem.
At the species level, A. lumbricoides and G. lamblia were identified as the dominant helminth and protozoan, respectively. This is consistent with global reports that highlight the ubiquity of these pathogens in settings with poor sanitation [31, 32]. The near-identical prevalence between males and females suggests similar exposure risks within household and community environments for this young age group, where behavioral differences are still limited. Public health interventions must therefore be tailored and implemented at a sub-national level to effectively target these high-risk settings.
Limitations
Our findings are subject to certain limitations. First, the restriction to English-language publications may have introduced a selection bias, potentially omitting relevant data from non-English speaking regions. Second, the significant statistical heterogeneity observed, while common in global meta-analyses, indicates that there are residual factors influencing prevalence that our model could not capture. Third, the lack of uniformly reported, granular data on key confounders such as specific WASH practices, education, and detailed household income limited our ability to adjust for these critical variables in the analysis. Fourth, the wide confidence intervals observed for certain subgroups indicate substantial uncertainty, as these estimates are based on a limited number of studies; therefore, these data should be interpreted with caution. Fifth, The use of ecological climate data may not capture micro-environmental variations that modify true exposure. Despite these limitations, this study represents the most comprehensive and systematic assessment to date of the global prevalence of intestinal parasitic infections among children under five years old.
Conclusions
This systematic review demonstrates that intestinal parasitic infections remain a significant and inequitable public health burden among children under five years of age, with the highest prevalence concentrated in low- and lower-middle-income countries, particularly in South Asia and Eastern sub-Saharan Africa, and with pronounced micro-geographical clustering in high-burden settings such as Amhara, Ethiopia. The findings further indicate that the observed burden is shaped by interacting socioeconomic and environmental determinants, including poverty, inadequate water and sanitation infrastructure, and climatic factors such as temperature and humidity, while also being likely underestimated due to the continued reliance on low-sensitivity diagnostic methods. To address these limitations, surveillance and national surveys should transition from conventional microscopy-based approaches to more sensitive diagnostic tools such as quantitative PCR, multiplex molecular assays, and enhanced concentration techniques, which enable improved detection of low-intensity infections and polyparasitism; these methods should be operationally embedded within routine sentinel surveillance systems and integrated into national health information platforms to improve spatial mapping of transmission and support evidence-based resource allocation. In parallel, effective control requires the implementation of hyper-localized, integrated public health interventions at district and sub-district levels, where mass drug administration is strategically combined with context-specific WASH interventions, including expansion of safe water access, school- and community-based sanitation infrastructure, and sustained hygiene behavior change programs, thereby enabling a more precise, efficient, and context-adapted response to persistent transmission hotspots.
Supplementary Information
Acknowledgements
The authors sincerely appreciate the kind cooperation of all the personnel at Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran.
Abbreviations
- IPI
Intestinal parasitic infection
- GBD
Global Burden of Disease
- WHO
World Health Organization
- STHs
Soil-transmitted helminths
- PRISMA
Preferred Reporting Items for Systematic Reviews and Meta-Analyses
- HDI
Human Development Index
- ELISA
Enzyme-linked immunosorbent assay
- CI
Confidence intervals
- WASH
Water, Sanitation, and Hygiene
Authors’ contributions
M.B, H.T, and A.V.E: conceptualized, supervised the study, and revised the original draft of manuscript. M.O: performed the formal analysis and data curation. I.A, S.H.M, A.B, M.H, and K.H.N: contributed to data curation and interpretation, supervised the study, and wrote and revised the original draft of manuscript. F.S.R: supervised and revised the original draft of manuscript. Z.G and F.M performed the literature search, data extraction, designed the tables. A.V.E: contributed to data interpretation, wrote and revised the original draft of manuscript. M.B: conceptualized, designed and wrote and revised the original draft of manuscript. All authors have checked and approved the final version of the manuscript.
Funding
This research was supported by Qazvin University of Medical Sciences (No.IR.QUMS.REC.1403.401).
Data availability
The datasets generated and/or analyzed during this study are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
This study received approval from the Institutional Review Board of Qazvin University of Medical Sciences, Qazvin, Iran, as recorded in the ethics documentation (no.IR.QUMS.REC.1404.231).
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Hassan Taherahmadi, Zahra Gharibi, Abouzar Babaei, Fatemeh Samiee-Rad and Faezeh Mohammadi contributed equally to this work.
Contributor Information
Meysam Olfatifar, Email: ol.meysam92@gmail.com.
Sayed Hussain Mosawi, Email: sayedhussain.mosawi@ghalib.edu.af.
Aida Vafae Eslahi, Email: Vafaeeslahia@gmail.com.
Milad Badri, Email: badri22.milad@gmail.com.
References
- 1.Animaw Z, Melese A, Demelash H, Seyoum G, Abebe A. Intestinal parasitic infections and associated factors among pregnant women in Ethiopia: a systematic review and meta-analysis. BMC Pregnancy Childbirth. 2021;21:474. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Ahmed T, Khanum H, Uddin MS, Barua P, Arju T, Kabir M, et al. Entamoeba histolytica, Giardia lamblia and Cryptosporidium spp. infection in children in an urban slum area of Bangladesh. Bioresearch Commun. 2016;2:175–81. [Google Scholar]
- 3.Chen J, Gong Y, Chen Q, Li S, Zhou Y. Global burden of soil-transmitted helminth infections, 1990-2021. Infect Dis Poverty. 2024;13:68–77. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Farrell SH, Coffeng LE, Truscott JE, Werkman M, Toor J, De Vlas SJ, et al. Investigating the effectiveness of current and modified World Health Organization guidelines for the control of soil-transmitted helminth infections. Clin Infect Dis. 2018;66 suppl_4:S253–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Gebretsadik D, Metaferia Y, Seid A, Fenta GM, Gedefie A. Prevalence of intestinal parasitic infection among children under 5 years of age at Dessie Referral Hospital: cross sectional study. BMC Res Notes. 2018;11:771. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Deka S, Kalita D, Hazarika NK. Prevalence and risk factors of intestinal parasitic infection in under-five children with malnutrition: a hospital based cross-sectional study. J Fam Med Prim Care. 2022;11:2794–801. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Taylor-Robinson DC, Maayan N, Donegan S, Chaplin M, Garner P. Public health deworming programmes for soil-transmitted helminths in children living in endemic areas. Cochrane Database Syst Rev. 2019;2019. [DOI] [PMC free article] [PubMed]
- 8.Murarkar S, Gothankar J, Doke P, Pore P, Lalwani S, Dhumale G, et al. Prevalence and determinants of undernutrition among under-five children residing in urban slums and rural area, Maharashtra, India: a community-based cross-sectional study. BMC Public Health. 2020;20:1559. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Ahmed M. Intestinal parasitic infections in 2023. Gastroenterol Res. 2023;16:127. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Herrick JA, Nordstrom M, Maloney P, Rodriguez M, Naceanceno K, Gallo G, et al. Parasitic infections represent a significant health threat among recent immigrants in Chicago. Parasitol Res. 2020;119:1139–48. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Abu-Madi MA, Behnke JM, Ismail A, Boughattas S. Assessing the burden of intestinal parasites affecting newly arrived immigrants in Qatar. Parasit Vectors. 2016;9:619. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Girma A, Genet A. Prevalence and factors associated with intestinal parasitic infections among preschool-aged children in Ethiopia: a systematic review and meta-analysis. Parasite Epidemiol Control. 2024;26:e00368. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Girma A, Genet A. Magnitude and determinants of intestinal parasites among children under five in Ethiopia during 2010--2023: a systematic review and meta-analysis. Fetal Pediatr Pathol. 2024;43:47–65. [DOI] [PubMed] [Google Scholar]
- 14.Abdoli A, Olfatifar M, Eslahi AV, Moghadamizad Z, Nowak O, Pirestani M, et al. Prevalence of intestinal protozoan parasites among Asian schoolchildren: a systematic review and meta-analysis. Infection. 2024:1-37. [DOI] [PMC free article] [PubMed]
- 15.Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Int J Surg. 2021;88:105906. [DOI] [PubMed] [Google Scholar]
- 16.Badri M, Olfatifar M, Sabzi S, Asghari A, Zaki L, Hatam-Nahavandi K, et al. The role of cockroaches as mechanical carriers of helminth infections: a systematic review and meta-analysis of environmental and climatic impacts on public health. Int J Environ Health Res. 2025:1-18. [DOI] [PubMed]
- 17.Badri M, Olfatifar M, Gharibi Z, Pal M, Hatam-Nahavandi K, Asghari A, et al. A systematic review and meta-analysis on the global prevalence of helminthic parasites among schoolchildren: a public health concern. BMC Public Health. 2025;25:2852. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Badri M, Olfatifar M, Wandra T, Budke CM, Mahmoudi R, Abdoli A, et al. The prevalence of human trichuriasis in Asia: a systematic review and meta-analysis. Parasitol Res. 2022:1-10. [DOI] [PubMed]
- 19.Chelkeba L, Mekonnen Z, Alemu Y, Emana D. Epidemiology of intestinal parasitic infections in preschool and school-aged Ethiopian children: a systematic review and meta-analysis. BMC Public Health. 2020;20:117. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Kang S, Damania A, Majid MF, Hotez PJ. Extending the global worm index and its links to human development and child education. PLoS Negl Trop Dis. 2018;12:e0006322. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Bradley RH, Putnick DL. Housing quality and access to material and learning resources within the home environment in developing countries. Child Dev. 2012;83:76–91. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Abou-Seri H, Abdalgaber M, Zahran F. Enteric parasitic infections: From environmental enteric dysfunction to gut microbiota and childhood malnutrition. Parasitol United J. 2022;15:216–23. [Google Scholar]
- 23.Bangert M, Molyneux DH, Lindsay SW, Fitzpatrick C, Engels D. The cross-cutting contribution of the end of neglected tropical diseases to the sustainable development goals. Infect Dis poverty. 2017;6:73. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Eslahi AV, Olfatifar M, Zaki L, Pirestani M, Sotoodeh S, Farahvash MA, et al. The worldwide prevalence of intestinal helminthic parasites among food handlers: A systematic review and meta-analysis. Food Control. 2023:109658.
- 25.Eslahi AV, Olfatifar M, Zaki L, Saryazdi AK, Barikbin F, Maleki A, et al. Global prevalence of intestinal protozoan parasites among food handlers: A systematic review and meta-analysis. Food Control. 2022:109466.
- 26.Pullan RL, Smith JL, Jasrasaria R, Brooker SJ. Global numbers of infection and disease burden of soil transmitted helminth infections in 2010. Parasit Vectors. 2014;7:37. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Freeman MC, Garn JV, Sclar GD, Boisson S, Medlicott K, Alexander KT, et al. The impact of sanitation on infectious disease and nutritional status: a systematic review and meta-analysis. Int J Hyg Environ Health. 2017;220:928–49. [DOI] [PubMed] [Google Scholar]
- 28.Downey AS. Prevention and control of enteric protozoan infections: Public health applications of environmental surveillance and drug treatment studies. The Johns Hopkins University; 2009.
- 29.Djawadi B, Parvizi N, Vazini H, Badri M, Eslahi AV, Adamopoulos I, et al. Genotyping and molecular profiling of intestinal microsporidiosis and cryptosporidiosis in HIV-infected patients in Alborz Province, Iran. Gut Pathog. 2025. [DOI] [PMC free article] [PubMed]
- 30.Mbong Ngwese M, Prince Manouana G, Nguema Moure PA, Ramharter M, Esen M, Adégnika AA. Diagnostic techniques of soil-transmitted helminths: impact on control measures. Trop Med Infect Dis. 2020;5:93. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.D’Alessandro AAB, Pedreira LE, Farias GS, Almeida SMM, Nery NDA, Paiva MJM, et al. prevalence and diversity of intestinal parasites in children around the world. Rev Gestão Soc e Ambient. 2024;18:1–12. [Google Scholar]
- 32.Dogan N. Intestinal parasites from past to present: taxonomy, paleoparasitology, geographic distribution, prevention and control strategies. In: Intestinal Parasites-New Developments in Diagnosis, Treatment, Prevention and Future Directions. IntechOpen; 2024.
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets generated and/or analyzed during this study are available from the corresponding author upon reasonable request.