pathegenen

Pathegenen are biological agents—such as bacteria, viruses, fungi, protozoa and prions—that can cause disease in hosts. They vary widely in size, structure, life cycle and the types of illness they produce, from localized infections to systemic and chronic conditions.

Bacteria are single-celled organisms that may produce toxins or invade tissues; examples include Mycobacterium tuberculosis and Salmonella species. Viruses are obligate intracellular parasites that hijack host cells to replicate, with examples such as influenza viruses and human immunodeficiency virus (HIV). Fungi can cause superficial or invasive infections, as seen with Candida and Aspergillus species. Protozoa, like Plasmodium species, often have complex life cycles and can cause diseases such as malaria. Prions are misfolded proteins that induce abnormal folding of normal proteins, associated with neurodegenerative disorders.

Transmission routes for pathegenen include direct contact, airborne spread, droplets, contaminated food or water, vectors (such as mosquitoes), and vertical transmission from mother to offspring. Disease severity depends on pathogen virulence, infectious dose, host immunity and environmental factors.

Control and prevention strategies include surveillance, vaccination, sanitation, use of personal protective measures, antimicrobial therapies and public health interventions. Ongoing research focuses on pathogen biology, diagnostics, treatment options and measures to reduce antimicrobial resistance. Understanding pathegenen is central to medicine, epidemiology and public health policy.