Expert reviewed • 08 January 2025 • 4 minute read
Disease transmission arises from complex interactions among pathogens, hosts, and the environment. By comprehending these transmission pathways, health professionals can implement more effective preventive and control strategies.
Diseases can spread through direct physical contact, such as skin-to-skin interaction, the exchange of bodily fluids, and sexual contact. Vertical transmission from mother to foetus also falls within this category. Additionally, droplet transmission occurs via larger respiratory droplets that settle quickly, usually requiring close proximity.
Pathogens often survive in the environment, making indirect routes significant. Fomite transmission involves contaminated surfaces or objects that harbour infectious agents. Meanwhile, airborne transmission utilises smaller droplets or droplet nuclei that remain suspended over longer distances, influenced by ventilation and airflow patterns.
Certain pathogens rely on biological vectors for their life cycle stages. For instance, insects may provide the optimal temperature, physiological environment, and behavioural conditions necessary for pathogen development. Vector competence—how well a vector supports pathogen survival—is crucial in understanding epidemic potential.
Other vectors simply carry pathogens from one place to another without pathogen multiplication. This mechanical transfer is often short-lived, but it can still initiate infection if the host is susceptible.
Climate conditions influence disease transmission. Temperature affects pathogen and vector survival, while humidity can alter droplet persistence and vector breeding habitats. Changing environmental conditions can thus shift transmission dynamics, often in unpredictable ways.
Technological and social factors now shape transmission pathways. Air conditioning systems, mass transportation, urban density, and global connectivity all contribute to the complexity of disease spread. Similarly, social customs, travel habits, healthcare access, and preventive measures, such as masks and hand hygiene, also influence infection patterns.