Diarrheal diseases remain a significant public health challenge, particularly in low- and middle-income countries, where children under the age of five are disproportionately affected [1] . Despite substantial global progress in reducing child mortality over the past few decades, the burden of diarrheal diseases continues to present a considerable challenge in certain regions, particularly in sub-Saharan Africa. Between 1990 and 2016, the global under-five mortality rate (U5MR) decreased from 93 deaths per 1000 live births to 41 per 1000, reflecting global advances in child health interventions [2] . However, in sub-Saharan Africa, the decline, though evident, has been less pronounced, with the U5MR falling from 183 to 79 deaths per 1000 live births over the same period [3] . Diarrheal diseases are not only a major cause of under-five mortality but also contribute significantly to malnutrition in these vulnerable populations [4] . In 2016, diarrheal diseases accounted for 8% of global under-five deaths, ranking as the fourth leading cause of child mortality, a burden that is most acute in sub-Saharan Africa and Southern Asia [3] .

Nigeria, in particular, has emerged as a key focal point in this crisis, ranking second only to India in terms of the absolute number of under-five deaths attributable to diarrheal diseases [3] . The country’s elevated mortality rates can be attributed to a confluence of socio-economic and environmental factors, including limited access to clean water, inadequate sanitation, and substandard hygiene practices [5] . These structural deficits are compounded by host-related factors such as poor nutritional status, gender, and the duration of breastfeeding, which further heighten the vulnerability of young children to diarrheal diseases [1] . The complex interplay of these risk factors underscores the need for targeted interventions to mitigate the mortality and morbidity associated with diarrhea in Nigeria and other similar settings.

Among the numerous pathogens implicated in childhood diarrhea, enteroparasites, including Cryptosporidium species, Entamoeba histolytica, and Giardia lamblia, play a critical role [6] . Notably, Cryptosporidium has emerged as the second most important pathogen following rotavirus, contributing significantly to the global burden of diarrheal disease in children under four years of age [7] . The Global Enteric Multicenter Study (GEMS) highlighted that Cryptosporidium is responsible for approximately 2.9 million cases of moderate-to-severe diarrhea (MSD) in children aged 0 to 2 years in sub-Saharan Africa alone, leading to an estimated 202,000 deaths annually among children under 24 months in this region and South Asia [8] . Given the significant role Cryptosporidium plays in childhood morbidity and mortality, its surveillance is critical in understanding its epidemiology, particularly in resource-limited settings where the burden is highest.

Despite the known importance of Cryptosporidium in causing diarrhea among children, the epidemiological data on its prevalence and associated risk factors remain sparse and often outdated in many parts of Nigeria. Previous studies in the country have either focused on limited populations or have failed to comprehensively address the role of Cryptosporidium as a causative agent of diarrheal disease [9] - [11] . Moreover, there is a growing recognition of the need to explore specific regional variations in the prevalence of the parasite, particularly in areas like Abakaliki, South-East Nigeria, where local health policies may benefit from updated data on the pathogen’s transmission dynamics.

The present study seeks to address this gap by investigating the prevalence of Cryptosporidium and identifying key risk factors for its transmission among children aged five years and below in selected health institutions in Abakaliki. Understanding the local epidemiology of Cryptosporidium is essential for guiding effective public health interventions and informing policy decisions aimed at reducing the burden of diarrheal diseases in Nigeria. This study is particularly timely, as it not only contributes to the global discourse on child health but also provides critical insights for local policymakers to formulate targeted interventions to curb the spread of Cryptosporidium infections.

The prevalence of Cryptosporidium infection observed in this study is lower than previous reports from Lagos in 2008, which focused on children under five years presenting with diarrhea [17] . However, it aligns more closely with findings from Kaduna State in 2014 [18] . This lower prevalence in Abakaliki is consistent with reports suggesting a general decline in diarrheal diseases over the years [2] . The 6.5% prevalence of Cryptosporidium infection found in this study is also lower than the 11.2% reported by Akinleye et al. in 2014 in Ibadan, where a broader age group of children aged 0 - 10 years was studied [19] . The restricted age range of children (0 - 5 years) in our study likely accounts for this difference.

Our study’s prevalence of 6.5% contrasts with a 12.5% prevalence reported in a similar study conducted at Mulago Hospital in Kampala, Uganda, among diarrheic children aged 9 - 36 months [20] . The higher prevalence in Uganda may reflect the fact that Cryptosporidium infection peaks in otherwise healthy children between 6 - 12 months and is more common in immunocompromised or undernourished children between 6 - 36 months [21] . These factors may not have been as prevalent in our study population, thereby explaining the lower prevalence in Abakaliki.

In this study, the only risk factor significantly associated with Cryptosporidium diarrhea was institutional home settings, where the prevalence of infection was markedly higher (50%) than in monogamous (6.2%) or polygamous (0.0%) households. This finding aligns with reports identifying Cryptosporidium as a significant pathogen in childcare institutions [22] . Given that all the detected species were C. hominis, a human-to-human transmitted parasite [23] , it is plausible that once an outbreak occurs in an institutional setting, close contact and shared living conditions facilitate the spread of the infection among children.

The prevalence of Cryptosporidium infection was higher in urban areas (7.9%) compared to rural settings (5.4%), though this difference was not statistically significant. This pattern contrasts with a study in Ibadan, where the prevalence was higher in rural areas (11.8%) than urban areas (10.3%) [19] . This discrepancy may be explained by the fact that C. hominis, identified in our study, is typically associated with urban environments, where human-to-human transmission is more common [23] . In contrast, Cryptosporidium parvum, the species identified in the Ibadan study, is linked with zoonotic transmission, which is more prevalent in rural settings [24] .

Our study also found that Cryptosporidium diarrhea was more common among children who were not exclusively breastfed (8.3%) compared to those who were (1.8%), although this difference was not statistically significant. This is consistent with previous studies, such as one conducted in 2012, which found that exclusive breastfeeding provides protection against diarrheal diseases [25] . Similarly, a 2014 study in rural and semi-rural areas of Tanzania identified that the onset of Cryptosporidium infection often coincided with changes in breastfeeding practices [26] . The small number of Cryptosporidium-positive cases in our study may have limited the statistical significance of this relationship, but the protective effect of exclusive breastfeeding remains evident [27] .

Interestingly, our findings revealed a higher prevalence of Cryptosporidium infection (7.7%) among children whose mothers had no formal education, while those whose mothers had primary education recorded the lowest prevalence (0.0%). This finding is in line with a 2017 study that found children of uneducated mothers were more likely to suffer from diarrhea compared to those whose mothers had higher levels of education [28] . However, it contrasts with a study in Cotonou, Benin Republic, where the highest prevalence of cryptosporidiosis was observed among children of parents with only primary education [29] . This variation may stem from different breastfeeding practices, as higher levels of maternal education are often associated with lower rates of breastfeeding [30] , which, as established, offers protection against diarrheal diseases [24] [31] .

The highest prevalence of Cryptosporidium infection in our study occurred among children aged 12 - 24 months, a finding consistent with studies that show diarrhea becomes more common by six months of age [26] . However, this contrasts with findings from western Venezuela, where the highest prevalence was found in children younger than one year [32] . The explanation may lie in environmental factors, such as increased exposure to contaminated soil as children begin to crawl or walk, thereby increasing their risk of infection [32] .

In terms of gender differences, the prevalence of Cryptosporidium infection was higher among males (7.4%) compared to females (5.1%), though this difference was not statistically significant. This contrasts with a study from Ibadan, where a higher prevalence was found in females [19] , but aligns with findings from Sweden, where males had a higher prevalence of cryptosporidiosis [33] . The higher prevalence among males may be due to behavioral differences, with boys potentially being more likely to explore unsanitary environments [34] . However, most studies agree that gender is not a major risk factor for Cryptosporidium infection [33] [35] .

Our study also found that children using water closets had a higher prevalence of infection (7.0%) compared to those using pit latrines (6.1%) or practicing open defecation (5.1%), though these differences were not significant. This contrasts with other studies that have found a significant association between open defecation and Cryptosporidium infection [32] . The use of non-sanitary toilet facilities may expose children to an increased risk of diarrheal diseases, including Cryptosporidium infection [36] .

This study has some limitations. The cross-sectional nature of the research only provides a snapshot of Cryptosporidium prevalence, without capturing seasonal or long-term trends. The sample size, while adequate, may still be insufficient to detect certain associations, especially with respect to exclusive breastfeeding and maternal education. Furthermore, the reliance on microscopy and molecular techniques limits the detection of other potential pathogens co-occurring with Cryptosporidium, which could have provided a more comprehensive picture of the diarrheal burden. These limitations suggest that further research with larger sample sizes and longitudinal designs is needed to fully understand the dynamics of Cryptosporidium infection in this region.

This study highlights a Cryptosporidium infection prevalence of 6.5% among children aged five years and below in Abakaliki, South-East Nigeria, with institutional home settings being the only significant risk factor. Other associated factors include male gender, lack of exclusive breastfeeding, and maternal education. These findings underscore the importance of targeted interventions to reduce the burden of Cryptosporidium diarrhea, particularly in childcare institutions, where human-to-human transmission appears to be a major contributor. The relatively higher prevalence in urban areas suggests that improving hygiene and sanitation, especially in densely populated regions, is crucial.

To address these findings, health policymakers should prioritize the improvement of sanitation facilities and hygiene practices, particularly in institutional childcare settings where overcrowding and close contact may facilitate the spread of infections. Healthcare providers are encouraged to intensify efforts to promote and support exclusive breastfeeding, which has been shown to offer protective benefits against diarrheal diseases. Additionally, community health workers should focus on educating mothers, particularly those with lower educational attainment, about the risks associated with poor hygiene and inadequate breastfeeding practices.

Public health authorities are urged to implement routine screening for Cryptosporidium in diarrheic children, particularly in institutional settings, to ensure early detection and effective management. Furthermore, additional research is recommended to explore seasonal trends and larger cohorts to enhance the understanding of Cryptosporidium infection dynamics in the region.

The authors would like to thank the administration of Parasittologisk Laboratorium, Institutt for Mattrygghet og Infeksjons biologi, NMBU, Oslo, Norway, for helping out in the serologic and molecular analyses.

OINO and CKO conceptualized and wrote the draft of the article. OINO and KEO anchored the sample and data collection. UVU anchored the data analyses and reviewed the manuscript. EDO, KEO, NCI, NMCI, CBE, CIJA, CCA, SCE, FOE, BAA, CSU, KA, AGO and UCI reviewed the manuscript.

The authors hereby transfer all copyright ownership exclusively to the journal, if this work is published by the journal.

Questionnaire on the Prevalence and Risk Factors for Cryptosporidium Diarrhea Among Children Aged 5 Years and Below.

SECTION 1: HOSPITAL ID

1) Serial Number: -------------------------

2) Hospital Name: ------------------------

3) Hospital Number: -----------------------

4) Month/Year of Admission: --------------------------------

Section 2: Biodata

1) Age of Child: Years -------------- Months -----------

2) Sex of Child: A. Male B. Female

3) Weight of Child: -----------------(kg)

4) Height of Child: ------------------(cm)

Section 3: Family History

1) Care Giver: A. Mother B. Nanny C. Granny D. Siblings E. Others (Specify)

2) Place of Residence: A. Rural B. Urban

3) Family type: A. Monogamous B. Polygamous C. Others (Specify ------------)

4) Mother’s Highest Education: A. Postgraduate B. First Degree C. SSCE D. FSLC E. None

5) Father’s Occupation: A. Professional B. Top Civil Servant C. Politician D. Middle level Bureaucrats E. Top Business men F. Skilled Artisans G. Unskilled Worker

Section 4: Presenting Complaint

1) When did the diarrhea start? (DD/MM/YY) ----------------------------------

2) When did it end? (DD/MM/YY) ----------------------------------

3) Any vomiting? A. Yes B. No

4) Any Fever? A. Yes B. No

5) Any Blood in Stool? A. Yes B. No

6) Any mucus in Stool? A. Yes B. No

Section 5: Feeding History

1) Exclusively breast fed? A. Yes B. No

2) If (1) above is Yes, how long did it last A. <4 months B. 4 - 6 months

3) Current form of feeding A. Exclusive Breastfeeding B. Complementary feeding C. Predominant feeding D. Exclusive Formula feed E. Supplementary/Mixed feeding

4) If Complementary, what are the constituents?

A) Commercial Cereals, e.g., Cerelac®

B) Local feeds, e.g., Pap

5) If Pap, fortified with -------------------------------------------------------------

6) Is the baby on bottle feeding? A. Yes B. No

7) Who prepares the baby’s food? A. Mother B. Nanny C. Granny D. Older Siblings E. Others (Specify ------------------------)

8) What is the Child’s source of Drinking Water? A. Vendors (e.g., Tankers) B. Borehole C. Well D. Rain E. Processed (e.g., Sachet, Bottle) F. Stream

9) Any form of Water treatment? A. None B. Boiling C. Chemical (Chlorine) D. Filtering

Section 6: Immunization History

1) Did the Child receive Rotavirus vaccine? A. Yes B. No

2) If YES where? A. AEFUTHA B. MILE 4 C. HEALTH CENTER D. PRIVATE HOSPITAL (Specify ----------------------------)

3) Did the Child receive Measles vaccine? A. Yes B. No

Section 7: Treatment History

1) Medications given to the Child:

2) Feeding during illness A. Yes B. No

3) If YES specify type of Food -----------------------------

Section 8: Outcome/Follow-Up

Phone Number of Care-Giver……………………………