Understanding Infectious Diseases

Infectious diseases are disorders caused by organisms such as bacteria, viruses, fungi, or parasites. Many live in and on our bodies, and while some are benign, others can cause severe diseases.

Pathogens can spread through various means: direct contact with infected individuals, indirect contact via surfaces, droplet inhalation, consumption of contaminated food/water, or vector-borne spread like mosquitoes.

Creating vaccines involves isolating a disease agent, creating an antigen to provoke an immune response, and extensive testing for efficacy and safety. Surprisingly, some vaccines come from weakened versions of the virus.

Herd immunity occurs when a high percentage of a community is immune to a disease, making its spread unlikely. This protects those who are not immune, but relies on widespread vaccine coverage.

Overuse and misuse of antibiotics have led to antibiotic resistance, a dire global health threat. Bacteria evolve rapidly, rendering treatments ineffective, and can share their resistance with other bacteria.

Smallpox is the only human disease to have been eradicated globally, thanks to a comprehensive vaccination campaign. Eradication is a complex process requiring international cooperation and persistent public health efforts.

Climate change and human encroachment on wildlife habitats have increased the emergence of zoonotic diseases—those transmissible from animals to humans, like Ebola and SARS-CoV-2, with potentially pandemic consequences.