An Introduction to Epidemiology

An Introduction to Epidemiology

Understanding the how’s and why’s of becoming sick is very important to keep us healthy. There are “disease detectives” called epidemiologists who specialize in understanding disease patterns, so that we know which precautions to take to keep ourselves and everyone around us healthy.

The spread of communicable or infectious disease evolved into what we now call “the germ theory”. Before the 1850’s, people used to think that foul smelling vapors called miasma caused illness. However, John Snow, the father of Epidemiology, challenged the miasma theory by mapping a cholera epidemic in Soho, London, from water sources and claimed that cholera must be water-borne, not air-borne. Since then, disease mapping has become very important in understanding disease patterns. A great interactive and up-to-date map can be found at

The rates of transmission of specific diseases is also important to understand. Endemic diseases, or diseases that are steady and do not fluctuate in a society (so transmission is only from one person to another), are not as much of a threat as epidemics or pandemics. Epidemics spread faster in a specific location, meaning that one person can infect multiple people, and can cause many people to become sick at once. Pandemics are epidemics on a global scale. And though infection from person to person is fairly common, the students learned that the most deadly animal is actually the mosquito, a vector (or carrier) for diseases.

In today’s lesson, the students modeled an epidemic through an activity where they spread an “infection” through the class by sharing contents of a cup with one another. They graphed their results and noticed the rate of infection was exponential, or an epidemic. At the start of the activity, only one of the students was “infected” and through multiple rounds, the infection spread. By the third round, eight students were infected! They realized that “patient zero”, or the first person to catch and spread the infection, is usually difficult to isolate and aside from prevention methods, these considerations are challenges epidemiologists face.

We ended the lesson by focusing on healthy habits or methods of prevention and elimination efforts. So far, only one human disease has been successfully eradicated through vaccination: smallpox. Guinea worm, though not through vaccinations, is also very close to being eradicated!


Introducción a las Enfermedades Infecciosas

Entender cómo y porqué nos enfermamos es muy importante a la hora de mantenernos saludables. Los epidemiólogos, son una especie de “detectives de enfermedades” ya que, su especialización es descifrar los patrones de las enfermedades y determinar cuales son las precauciones debemos tomar para protegernos de éstas.

La propagación de la enfermedad contagiosa o infecciosa se convirtió en lo que ahora llamamos ” la teoría del germen “. Antes del 1850, la gente solía pensar que por sólo oler vapores malolientes (miasma) se podían enfermar. Sin embargo, John Snow, el padre de la Epidemiología, desafió esta idea del misma al trazar un mapa de la epidemia de cólera en la zona de Soho en Londres. Snow demostró que la causa del cólera era las fuentes de agua contaminadas en la ciudad, y por tanto esta enfermedad no se transmitía por el aire. Desde esa instancia el “mapeo de las enfermedades” se convirtió en una herramienta muy importante para comprender sus patrones. Puedes encontrar un mapa interactivo y actualizado en:

Otro concepto importante en epidemiología son las tasas de transmisión.  Las enfermedades endémicas, o enfermedades que son estables y no varían en una sociedad (transmisión de persona a persona), no son una amenaza como lo son las epidemias o pandemias. Las epidemias se extienden más rápido en un lugar específico, lo que significa que una persona puede infectar a varias personas  y puede hacer que muchas personas se enferman al mismo tiempo. Las pandemias son epidemias a escala global. Aunque la infección de persona a persona es bastante común, los estudiantes aprendieron que el animal más mortal es en realidad el mosquito porque es un vector (o vehículo ) para enfermedades.

En la clase de hoy los estudiantes simularon una epidemia; propagaron una infección entre sus compañeros al compartir entre todos los contenidos de una taza. Graficaron los resultados y se dieron cuenta que la tasa de infección fue exponencial, es decir una epidemia. Al comienzo de la actividad solo uno de los estudiantes estaba “infectado”. Después de compartir la taza tres veces, ¡ocho estudiantes se infectaron! Con esta actividad, los estudiantes se dieron cuenta que es muy difícil aislar a la primera persona que se enferma (paciente cero).

Terminamos la clase hablando sobre hábitos saludables o métodos de prevención. Hasta ahora, la única enfermedad humana que ha sido exitosamente erradicada a través de la vacunación, es la viruela. La enfermedad por el gusano de Guinea está muy cerca de ser erradicada.


Lauren Koppel

Lauren earned a Bachelor’s degree with a double major of Biology and Psychology from Clark University, and a Master of Education from the Harvard Graduate School of Education. During her undergraduate years, she worked in a evolutionary neurobiology lab that studied the neural development of annelids (marine worms), with a focus on the sox family of genes. Lauren loves learning about how the world works (including everything from biology to chemistry to engineering), and is passionate about sharing that knowledge and enthusiasm with others. In the past, she has interned at the Museum of Science, where she educated learners of all ages through hands-on activities, games, and experiments. Other science education organizations with which Lauren has worked include The People’s Science, EurekaFest, and Eureka! of Girls Inc. of Worcester. Currently she lives in Boston, where devotes her free time to playing Quidditch, reading sci-fi novels, playing her ukulele, and enjoying all the culinary delights the city has to offer.

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