Infectious Diseases

Infectious diseases are illnesses caused by the direct or indirect transmission of an infectious agent—such as bacteria, viruses, parasites, or fungi—from one host to another. These diseases are among the oldest threats to human health and have historically exerted profound effects on social, economic, and political structures. The spread of infectious diseases can occur through person-to-person contact, respiratory droplets, contaminated food and water sources, vectors such as mosquitoes, or infected surfaces.

Although advances in modern medicine have greatly improved control over infectious diseases, the emergence of new pathogens and the re-emergence of existing ones have sustained the relevance and importance of this field. Today, outbreaks and epidemics that still pose global public health risks continue to strain healthcare systems and are becoming increasingly complex due to factors such as human mobility and climate change.

Infectious Diseases Through History

Ancient and Medieval Periods

One of the earliest documented epidemics in history occurred in Athens in 430 BCE during the Peloponnesian War, causing massive casualties. At the time, the origins of diseases were not understood and were often interpreted as divine punishment or the influence of evil spirits. Although physicians such as Hippocrates and Galen made observations regarding the transmission of infectious diseases, no microbiological explanations were developed.

In 14th-century medieval Europe, the plague (Black Death) killed millions and profoundly disrupted the continent’s social structure, economic balance, and belief systems. During this period, quarantine practices were introduced, particularly in port cities, where incoming ships were required to remain isolated for a set period in an effort to reduce transmission.

Ottoman and Early Republican Periods

During the Ottoman Empire, diseases such as plague, cholera, and typhus periodically caused significant loss of life, especially during wartime when outbreaks were common. The state placed importance on quarantine measures and hygiene regulations, employing health officials to monitor infectious diseases.

Archival records from the National Struggle period document the high prevalence of diseases such as smallpox, typhus, and malaria in cities like İzmir, alongside inadequate healthcare services. During the early Republican period, modern public health practices were adopted, including vaccine production, health education, and the establishment of water and sewage infrastructure, leading to structural transformations in the fight against infectious diseases.

Major Infectious Diseases

Plague

Plague, a bacterial disease, has caused three major pandemics throughout history. The Black Death of the 14th century killed approximately one-third of Europe’s population and left deep marks in historical memory. Transmitted by fleas on rodents, the disease manifests with fever, swollen lymph nodes, and hemorrhagic symptoms. It played a pivotal role in the origins of quarantine practices.

Cholera

Cholera, caused by the bacterium Vibrio cholerae, spreads primarily through contaminated water sources. A series of cholera outbreaks occurred in 19th-century Europe and Ottoman territories. The disease progresses with severe diarrhea and dehydration and can have a high mortality rate. It has been brought under control through access to clean drinking water and improved sanitation measures.

Smallpox

Smallpox is a highly contagious disease caused by the variola virus, characterized by fever and skin rash. It caused the deaths of millions over centuries but was eradicated worldwide in 1980 following successful global vaccination campaigns led by the World Health Organization. This remains the first and only human infectious disease to have been completely eradicated in history.

Malaria

Malaria, caused by the Plasmodium parasite, is transmitted by mosquitoes. It presents with symptoms such as fever, chills, and sweating. Throughout history, it has affected vast regions and placed heavy burdens on healthcare systems, particularly in tropical areas. Control efforts have included chemical drugs, insect repellents, and the draining of marshlands.

Typhus and Typhoid

Typhus, spread by lice and fleas, became widespread during wartime under poor hygiene conditions and caused the deaths of millions of soldiers. Typhoid, on the other hand, is a different infection caused by Salmonella bacteria and typically spreads through contaminated water and food. Both diseases present with symptoms such as fever, weakness, and diarrhea.

Strategies for Combating Infectious Diseases

Quarantine and Isolation Practices

Quarantine is the practice of separating individuals who may be carrying an infectious disease from healthy populations for a specified period. This method temporarily removes individuals who show no symptoms but may still transmit the disease. The first systematic quarantine measures were introduced in the 14th century during plague outbreaks in Venetian ports, where crews of arriving ships were held under observation for 40 days. In the Ottoman Empire, quarantine institutions were established in the 19th century, with quarantine stations activated in port cities to prevent the spread of infectious diseases.

Isolation refers to the complete separation of individuals diagnosed with an infection to prevent disease transmission. This practice can be implemented in hospitals, homes, or dedicated isolation centers. The critical importance of isolation as a public health measure was once again demonstrated during the COVID-19 pandemic. Both quarantine and isolation are indispensable not only for protecting individuals but also for safeguarding the overall health of the community.

Vaccination Programs

Vaccines confer immunity to individuals against specific diseases, providing personal protection and contributing to the development of herd immunity. From the mid-20th century onward, effective vaccines were developed against numerous infectious diseases, including polio, smallpox, measles, diphtheria, and pertussis. Thanks to global immunization programs led by the World Health Organization (WHO), smallpox was eradicated worldwide in 1980.

In Türkiye, vaccination efforts began shortly after the proclamation of the Republic in the 1920s, with expanded immunization programs introduced in the 1960s. From the 2000s onward, newer vaccines such as those for hepatitis B, chickenpox, rotavirus, and HPV were incorporated into the national schedule, and widespread vaccination campaigns were conducted in schools, family health centers, and hospitals. These efforts have played a critical role in reducing child mortality and controlling infectious diseases.

Health Education and Awareness

Public awareness of infectious diseases is a fundamental strategy for preventing and controlling outbreaks. Educating communities on personal hygiene practices, regular handwashing, use of clean water sources, proper waste disposal, and safe food consumption significantly reduces disease transmission.

To this end, public institutions produce brochures, television and radio spots, social media campaigns, school-based health education, and community outreach programs aimed at reaching all segments of society. Information campaigns conducted especially in rural areas and low-income communities also help reduce health disparities. Improving health literacy empowers individuals to protect their own health and fosters a sense of responsibility toward their surroundings.

Combating Infectious Diseases in the Republican Era

After the proclamation of the Republic, structural reforms were implemented in the health sector, and the fight against infectious diseases became a cornerstone of national health policy. Through the establishment of the Hıfzıssıhha Institute, domestic vaccine production began, and rural areas were reached through health clinics and mobile health teams. Between 1920 and 1940, both curative and preventive policies were pursued in the fight against malaria, typhoid, and tuberculosis.

Additionally, efforts to train healthcare personnel, establish statistical surveillance and reporting of infectious diseases, and improve water and sewage systems were undertaken to reduce the public health burden. Public health investments during these years significantly brought the spread of infectious diseases under control.

Infectious Diseases Today

In the 21st century, infectious diseases remain a fundamental threat to public health. Alongside classical infections, newly emerging or re-emerging diseases such as COVID-19, Ebola, Zika, and SARS hold significant positions on the global health agenda. The spread of these diseases is not limited to biological agents alone; it is directly linked to multidimensional socioeconomic and environmental factors including antimicrobial resistance, rapid and unregulated urbanization, climate change, natural disasters, armed conflicts, and forced migration.

Technological advances in modern medicine, improvements in diagnostic and treatment methods, the use of digital data monitoring systems, and international collaboration among health organizations offer significant opportunities in the fight against infectious diseases. Nevertheless, every country must develop sustainable, inclusive, and preventive policies within its own healthcare infrastructure.

Under the guidance of international organizations, primarily the World Health Organization (WHO), global health security strategies have established monitoring systems, early warning mechanisms, and mobile health teams as essential tools for the early detection, surveillance, and rapid response to infectious diseases.

Warning: The content in this article is provided solely for general encyclopedic informational purposes. The information here should not be used for diagnosis, treatment, or medical advice. Before making any decisions regarding health matters, you must consult a physician or qualified healthcare professional. The author and KÜRE Encyclopedia assume no responsibility for any consequences arising from the use of this information for diagnostic or therapeutic purposes.