Efficacy of Stool Concentration Techniques versus Direct Wet Mount Microscopy in Detecting Intestinal Parasites: A Cross-Sectional Study at a Tertiary Care Hospital in Western Nepal

Abstract

Introduction: Intestinal parasitic infections remain a significant public health problem in Nepal. Accurate diagnosis guides effective treatment and control. Direct wet mount microscopy, though commonly used, has limited sensitivity. Concentration techniques such as zinc sulfate flotation and formal-ether sedimentation may improve diagnostic results, but data comparing their efficacy in western Nepal are scarce.

Aims: To compare the efficacy of concentration techniques with the routine method for diagnosing intestinal parasitosis.

Methods: A cross-sectional study was conducted among 383 patients attending the inpatient and outpatient departments of Nepalgunj Medical College Teaching Hospital, Kohalpur, Nepal. Stool samples were examined by three methods: direct wet mount (saline and iodine), zinc sulfate flotation, and formal-ether sedimentation. Detection rates of the three methods were compared. Demographic and clinical data were collected using a semi-structured questionnaire.

Results: The overall detection rates were 11.75% (45/383) for direct wet mount, 14.88% (57/383) for zinc sulfate flotation, and 17.75% (68/383) for formal-ether sedimentation. Formal-ether sedimentation detected 23 more positives than wet mount (51.1% increase) and 12 more than zinc sulfate flotation (a 21.05% increase). Entamoeba histolytica (32 cases) and Ascaris lumbricoides (27 cases) were the predominant parasites. Mixed infections (7 cases) were detected exclusively by formal-ether sedimentation. Ascaris lumbricoides was predominantly seen in individuals under 20 years (93.75%), while E. histolytica occurred across all age groups, with the highest in those over 60 years.

Conclusion: Formal-ether sedimentation was the most sensitive method for detecting intestinal parasites, followed by zinc sulfate flotation. Both concentration techniques significantly outperformed direct wet mount microscopy. Routine use of concentration techniques, particularly formal-ether sedimentation, is recommended for accurate diagnosis of intestinal parasitosis in clinical laboratories.