The term “super - spreader” is used for multiple, and sometimes even conflicting, purposes. The reasons for this can be traced back to its complex history. Forerunners of the super - spreader concept - in discussions of so - called dangerous carriers and in analyses of explosive outbreaks during the early 20th century - revolved primarily around gastrointestinal diseases, not respiratory ones. In 1957 - 58, the H2N2 influenza pandemic and Wells and Riley 's studies on tuberculosis drew attention to both the viability of airborne transmission and the existence of significant heterogeneity in infectivity. The term super - spreader was coined in 1972, in relation to computer simulations of influenza epidemics. Initially, super - spreaders were simply an additional feature within stochastic models of epidemics, with little effect on an epidemic 's eventual course. The term was later appropriated to explain why outbreaks of airborne diseases continued in vaccinated populations, defying the predictions of contact - transmission - based models. The content and meaning of the term continued to fluctuate, from the mathematical characterisation of sexually active people with gonorrhoea, through HIV carriers with highly infectious semen, to central nodes within a network. This historical review reconstructs the historical growth of the concept of super - spreading, and offers insight into its current, highly diversified use.

1. Introduction

The concept of the “super - spreader” has become increasingly prominent in modern epidemiological discussions, especially in the context of global infectious disease outbreaks such as Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), and most recently, Coronavirus Disease 2019 (COVID - 19). However, the origin and evolution of this concept are deeply rooted in the history of epidemiology, shaped by scientific discoveries, changing disease patterns, and the development of mathematical models. Understanding the historical evolution of the super - spreader concept is crucial for grasping its significance in contemporary epidemiology and for developing effective public health strategies.

2. Early Conceptions: Dangerous Carriers and Outbreak Analyses

2.1 Gastrointestinal Diseases and “Typhoid Mary”

The idea of individuals being particularly efficient at spreading disease can be traced back to the early 20th century, mainly in the context of gastrointestinal diseases. One of the most famous early examples is Mary Mallon, better known as “Typhoid Mary”. In the early 1900s, Mary, an asymptomatic carrier of the typhoid bacillus, worked as a cook in New York City. It is estimated that she infected at least 53 people over the course of her career, with three deaths attributed to the disease she spread. Her case was remarkable because she remained asymptomatic herself, making it difficult to identify her as the source of infection. This led to the concept of “dangerous carriers”, individuals who, without showing symptoms, could spread disease to others. The focus at this time was on diseases transmitted through the fecal - oral route, and Mary's case was a wake - up call for public health authorities regarding the importance of tracking and controlling such carriers.

2.2 Analyses of Explosive Outbreaks

During this period, epidemiologists also began to analyze explosive disease outbreaks. They noticed that in some cases, a small number of individuals seemed to be responsible for a disproportionately large number of new infections. For example, in certain cholera outbreaks, specific individuals were found to have come into contact with a large number of people in settings where hygiene was poor, such as crowded tenements or markets. These individuals, although not yet formally labeled as “super - spreaders”, were recognized as key drivers of disease spread. However, the understanding of the mechanisms behind their high infectivity was limited, and the concept was more observational than theoretical.

3. The 1950s - 1970s: Airborne Transmission and the Coining of the Term

3.1 The H2N2 Influenza Pandemic and Airborne Transmission Studies

In 1957 - 58, the H2N2 influenza pandemic brought new attention to the field of epidemiology. This pandemic, which originated in East Asia and quickly spread globally, killed millions of people. During this time, researchers such as Wells and Riley conducted important studies on tuberculosis, which is an airborne disease. Their work demonstrated the viability of airborne transmission, showing that infectious particles could remain suspended in the air and infect individuals over relatively long distances. This was a significant shift in the understanding of disease transmission, as previously, the focus had been more on direct contact or fecal - oral transmission. The studies also hinted at the existence of significant heterogeneity in infectivity among individuals. Some people seemed to be more likely to spread the disease when infected, setting the stage for the formal concept of the super - spreader.

3.2 The Coining of the Term “Super - Spreader”

In 1972, the term “super - spreader” was coined in relation to computer simulations of influenza epidemics. Scientists were using these simulations to better understand how diseases spread through populations. Initially, super - spreaders were seen as an additional feature within stochastic models of epidemics. In these models, they were individuals who, due to their unique contact patterns or other factors, had a higher probability of infecting others. However, at this stage, they were not thought to have a major impact on the overall course of an epidemic. The models were more focused on average transmission rates, and super - spreaders were considered outliers that did not significantly alter the long - term outcome of the disease spread.

4. The 1980s - 1990s: Expanding the Concept in Different Disease Contexts

3.1 Sexually Transmitted Diseases and High - Risk Populations

In the 1980s, with the emergence and rapid spread of the Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS), the concept of the super - spreader took on new dimensions. Epidemiologists studying the spread of sexually transmitted diseases, including HIV, began to identify certain groups of individuals who were more likely to transmit the virus. For example, among sexually active people with gonorrhea, mathematical characterizations were made to identify those who had a higher number of sexual partners and were thus more efficient at spreading the disease. In the case of HIV, there was also discussion about carriers with highly infectious semen. These individuals, often part of high - risk sexual networks, were considered in the context of the super - spreader concept. Their behavior and the nature of the disease transmission led to a re - evaluation of how to control the spread of sexually transmitted diseases, with a greater focus on targeting these high - risk individuals.