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Impact of the COVID-19 Pandemic on Intestinal Parasitic Infection Positivity Rates Among Clinically Suspected Patients at a Tertiary Centre in Northern India: A Four-Year Retrospective Analysis

Year: 2026

Type: article

Abstract: BACKGROUND: The COVID-19 pandemic changed healthcare-seeking behaviour and clinical priorities, potentially influencing the detection of intestinal parasitic infections (IPIs). Data evaluating these effects remain limited. OBJECTIVE: The primary objective was to assess changes in the laboratory positivity rate of intestinal parasitic infections (IPIs) among clinically suspected patients during the COVID-19 pandemic, including the period of empirical ivermectin use. The secondary objective was to compare IPI positivity rates across different age and gender groups over the study period. METHODOLOGY: This was a retrospective laboratory-based observational study conducted at AIIMS Rishikesh from January 1, 2019, to December 31, 2022. Stool samples underwent macroscopic examination, saline and iodine wet-mount microscopy, and modified Ziehl-Neelsen staining for coccidian parasites. The timeline was divided into three policy-defined periods: pre-COVID (January 1 to December 31, 2019), early COVID-19/ivermectin-included period (January 1, 2020, to August 31, 2021), and late COVID-19/post-ivermectin period (September 1, 2021-December 31, 2022). We applied a chi-square test and Bonferroni correction. Effect sizes are reported as prevalence ratios (PRs) with 95% confidence intervals (CIs). RESULTS: Of 5,389 samples, 97 (1.80%) were confirmed positive for IPIs; 103 parasites were isolated from 97 patients, with five patients harbouring co-infections. Overall positivity rates were highest in the age group of 41-50 years (3.00%; 13/433) and comparable between male (1.88%; 64/3,405) and female (1.66%; 33/1,984) patients. The pre-COVID positivity rate (2.78%; 37/1,330) exceeded that of the early COVID period (1.14%; 17/1,493; PR = 2.44, 95% CI: 1.38-4.32; p = 0.001). Protozoa predominated, with Giardia lamblia being the most frequent (44.66%; 46/103 parasites isolated). Following ivermectin withdrawal, positivity declined transiently (0.14%; 1/692; 95% CI: 0.03%-0.81%) before resurging (2.24%; 42/1,874). CONCLUSION: Laboratory positivity for IPIs among patients with clinical suspicion fell during the initial COVID-19 period, most likely due to decreased healthcare-seeking and changes in referral patterns rather than a real shift in parasite prevalence at the community level. The observed temporal association with ivermectin use is only hypothesis-generating because individual-level treatment information is not available. Prospective, controlled studies that confirm ivermectin exposure data are required.

Source: Cureus

DOI: 10.7759/cureus.117132