There's something surprising that helps determine how damaging a disease is: distance.

LEARN MORE

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To learn more about this topic, start your googling with these keywords:

• Direct transmission: occurs when a pathogen is transmitted to a new host by physical or close contact
• Virulence: the degree of damage a pathogen causes its host

CREDITS

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Script Writer: Kate Yoshida Script Editor: Alex Reich Video Illustrator: Ever Salazar Video Director: Kate Yoshida and Alex Reich Video Narrator: Kate Yoshida With Contributions From: Henry Reich, Emily Elert, Peter Reich, David Goldenberg Music by: Nathaniel Schroeder

MinuteEarth is produced by Neptune Studios LLC https://neptunestudios.info

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REFERENCES

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Blanquart, F., et al. (2016). A transmission-virulence evolutionary trade-off explains attenuation of HIV-1 in Uganda. Elife 5: 5.

de Roode, J.C., Yates, A.J., & Altizer, S. (2008). Virulence-transmission trade-offs and population divergence in virulence in a naturally occurring butterfly parasite. Proceedings of the National Academy of Science 105: 7489-7494

Ewald, P.W. (1983). Host-parasite relations, vectors, and the evolution of disease severity. Annual Reviews Ecology & Systematics 14: 465-485

Ewald, P.W. (1991). Waterborne transmission and the evolution of virulence among gastrointestinal bacteria. Epidemiology & Infection 106: 83-119.

Ewald, P.W. (1991). Transmission modes and the evolution of virulence: with special reference to cholera, influenza, and AIDS. Human Nature 2: 1-30.

Galvani, A.P. (2003) Epidemiology meets evolutionary ecology. Trends in Ecology & Evolution 18: 132-139.

Lipsitch, M. & Moxon, E.R. (1997). Virulence and transmissibility of pathogens: what is the relationship? Trends in Microbiology 5: 31-37.