Saliva and Urine-Based Non-Invasive Strategies for Rabies Virus (RABV) Detection: Current Perspectives and Future Directions

Rabies remains a fatal zoonotic disease and a significant public health concern, particularly in underdeveloped countries. Although effective vaccines exist, early diagnosis and timely intervention are limited due to the lack of reliable, non-invasive diagnostic methods. Conventional techniques, such as direct fluorescent antibody testing of brain tissue and invasive sampling methods like cerebrospinal fluid analysis or skin biopsies, are often impractical in low-resource and field settings. This review aims to explore the potential of non-invasive biomarkers, specifically saliva and urine, for the early diagnosis of rabies and to evaluate their role in improving surveillance and disease management. A comprehensive review of recent literature was conducted focusing on non-invasive diagnostic approaches for rabies. Studies involving saliva and urine samples were analyzed, particularly those utilizing molecular techniques such as RT-PCR, RT-qPCR, RT-LAMP, as well as emerging technologies including CRISPR-based assays, biosensors, and point-of-care diagnostic tools. Saliva and urine have emerged as promising non-invasive diagnostic samples due to the intermittent shedding of rabies virus during the clinical phase. Saliva-based diagnostics demonstrated higher sensitivity and feasibility, especially when analyzed using advanced molecular techniques. Urine also provides an accessible and patient-friendly medium for detection. Recent innovations, including CRISPR-based methods and portable diagnostic kits, have enhanced the potential for rapid and large-scale surveillance. However, challenges such as low viral load, intermittent viral shedding, and lack of standardized sample collection protocols persist. Non-invasive diagnostic approaches using saliva and urine represent a transformative advancement in rabies detection. Despite existing limitations, continued technological improvements and standardization efforts could significantly enhance early diagnosis, surveillance, and patient management, contributing to the global “Zero by 2030” goal for rabies elimination.