Parasitic protozoa: Biosystematics, identification, pathogenicity, causes and remedial measures

Protozoans are widely distributed unicellular eukaryotic microorganisms that are either free-living or inhabit other organisms as ecto- or endoparasites. Parasitic protozoans-associated diseases impose huge health complications especially in developing countries and are responsible for millions of morbidities and mortality worldwide each year. These diseases are often linked to poor hygiene, inadequate sanitation, and general neglect. For diagnosis of parasitic protozoans, microscopy, combined with various staining techniques, remains the gold standard due to its simplicity and accessibility. However, newer diagnostic methods, including molecular techniques and AI-based approaches, are gaining popularity for their higher sensitivity and ability to process multiple samples simultaneously. Current anti-protozoal drugs have limitations, accompanying toxic effects further the growing emergence of drug-resistant protozoan species, has made effective treatment ever more challenging. Advance research on target-specific, multi-dimensional vaccines and drug repurposing strategies offers hope for more effective disease control and management. Preventive measures, such as promoting health education, maintaining personal hygiene, and ensuring proper sanitation, are essential for reducing the spread of protozoan infections. This review article provides an overview of major parasitic protozoans, the factors facilitating their transmission, and recent advances in their diagnosis and control strategies.