infectionsparticularly

Infection refers to the invasion and multiplication of organisms such as bacteria, viruses, fungi, or parasites within a host, where they may cause tissue damage and disease. Infections can range from mild to life-threatening and may affect any body site. It is important to distinguish infection from colonization, where organisms are present without causing symptoms. Transmission occurs through multiple routes, including direct contact, respiratory droplets, airborne spread, contaminated food or water, vectors such as mosquitoes, sexual contact, and vertical transmission from mother to child.

Common pathogens and types include bacterial, viral, fungal, and parasitic infections. Each type can present with different clinical features depending on the organism and site affected. Diagnosis relies on clinical assessment supported by laboratory tests such as cultures, microscopy, polymerase chain reaction, antigen or antibody tests, and imaging when needed.

Treatment depends on the causative organism. Bacterial infections are treated with antibiotics, viral infections with antivirals when available, fungal infections with antifungals, and parasitic infections with antiparasitics. Supportive care is often important. Antimicrobial resistance is a major global concern, making stewardship—using the right drug, dose, and duration—crucial to preserve effectiveness and minimize side effects.

Prevention and control include vaccination, hand hygiene, safe food and water practices, safe sex, vector control, and infection-control measures in healthcare settings. Public health measures such as surveillance, outbreak investigation, and ensuring access to vaccines and medicines play key roles.

At-risk groups include young children, older adults, pregnant people, and immunocompromised individuals. Outcomes vary with the pathogen, host factors, and timely, appropriate management.