Infectious Diseases

Infectious diseases are illnesses caused by bacteria, viruses, fungi, or parasites that can spread between people, animals, or through the environment. They range from common colds and flu to life‑threatening conditions like tuberculosis, HIV, Ebola, and malaria.

These diseases spread in different ways: through the air (influenza), contaminated food or water (cholera), insect bites (malaria, dengue), or direct contact with blood and body fluids (HIV, Ebola). Because they can move quickly through communities, they remain a central focus of global health policy.

Tuberculosis is currently the leading killer among infectious diseases, with more than 10 million new cases and about 1.25 million deaths in 2024. Malaria also remains a major threat, with an estimated 263 million cases and nearly 600,000 deaths in 2023, mostly in a small group of high‑burden countries.

HIV, influenza, and neglected tropical diseases add a huge additional burden, especially in low‑ and middle‑income settings. Many of these deaths are preventable with timely diagnosis, treatment, and vaccination—highlighting the gap between available tools and real‑world access.

A large global study recorded 3013 infectious disease outbreak events between 1996 and 2023, with influenza, Ebola, and MERS‑CoV among the most frequently reported. Vector‑borne diseases such as dengue and cholera have caused millions of cases in recent years, including a dengue outbreak with about 5 million cases and 5000 deaths in 2023.

In 2025 alone, at least 102 outbreaks with human transmission have been reported across 66 countries, from measles and mpox to cholera and hemorrhagic fevers. Some, like Marburg and Ebola, are rare but extremely deadly, with case fatality rates above 60% in certain events. These patterns show that outbreaks are not exceptional—they are now a constant feature of global health.

Several forces are driving today’s infectious disease trends: declining vaccination coverage, antimicrobial resistance, climate change, rapid urbanization, and intense global travel and trade. War, displacement, and underfunded health systems further weaken the ability of countries to detect and contain new threats.

Warming temperatures and changing rainfall patterns allow mosquitoes and other vectors to expand into new areas, bringing dengue, malaria, and other infections with them. At the same time, misuse of antibiotics is making common bacterial infections harder—and sometimes nearly impossible—to treat.

On a personal level, staying up to date on recommended vaccines, practicing hand hygiene, using condoms, and following safe food and water practices are among the most effective protections. When traveling, checking health advisories, using insect repellent and bed nets in mosquito‑risk areas, and seeking pre‑travel medical advice can significantly cut your chances of infection.

At the community and policy level, investing in primary health care, laboratories, disease surveillance, and rapid outbreak response saves lives and money. Public demand for transparent communication, equitable access to vaccines and treatments, and responsible antibiotic use all help slow the spread of infectious diseases and prepare the world for the next outbreak.