Temporal Trends and Demographic Determinants of Intestinal Protozoan Infections in the Eastern Cape, South Africa: A Retrospective Laboratory-Based Study (2021–2024)

Background: Intestinal protozoan infections are a major cause of gastrointestinal disease in low- and middle-income countries, particularly in sub-Saharan Africa, where inadequate sanitation, unsafe water, and socioeconomic inequalities facilitate transmission. In South Africa, updated epidemiological data on temporal trends and demographic risk factors, especially in rural provinces such as the Eastern Cape, remain limited. This study assessed the prevalence, temporal patterns, and demographic determinants of intestinal protozoan infections using laboratory surveillance data. Methods: A retrospective laboratory-based study was conducted using stool examination records from 1,909 individuals tested for intestinal parasites in healthcare facilities across the Eastern Cape Province (2021–2024). Demographic variables, including age, sex, and facility type, were extracted from laboratory records. Annual prevalence trends were described, and associations between infection status and demographic variables were assessed using chi-square tests and relative risk estimates with 95% confidence intervals. Results: Of the 1,909 stool samples, 404 were positive for intestinal protozoa, yielding an overall prevalence of 21.2%. Identified species included Cryptosporidium parvum (55.2%), Cystoisospora belli (44.1%), and Blastocystis hominis (0.7%). Infection prevalence increased from 17.1% in 2021 to 37.6% in 2022, declined to 21.3% in 2023, and rose slightly to 24.0% in 2024. Age was significantly associated with infection (χ2 = 132.6, p < 0.001), with the 31–40 year age group at highest risk (RR = 2.60; 95% CI: 2.04–3.31). Gender was not significantly associated with infection (p = 0.65). Facility type was significantly associated with infection (χ2 = 21.32, p < 0.001), with suburban healthcare attendees at higher risk than rural attendees (RR = 1.66; 95% CI: 1.31–2.11). Conclusions: Intestinal protozoan infections remain prevalent in the Eastern Cape, with C. parvum predominating. Temporal fluctuations and associations with age and healthcare facility type suggest environmental and socioeconomic factors influence transmission. Strengthened surveillance, improved water and sanitation infrastructure, and targeted public health interventions are essential to reduce the burden of protozoan infections in rural South African communities.