Environmental factors in disease transmission

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Chile's Institute of Hygiene, 1900 
Image credit: Archivo Fotográfico, FC-004067, www.memoriachilena.com

Many patients who fell victim to smallpox and plague experienced deadly symptoms that weakened their health, creating new transmission vectors which were in turn enhanced by the non-hygenic environments of Chile’s poorer neighborhoods. In 1872, doctors described smallpox patients as having severe dry cough, inflammation in the digestive tract, and serious chest congestion. Since the smallpox virus is transmitted through both airborn and surface contamination, coughing increased the risk of transmission both for those sharing environments with infected patients and for anyone coming into contact with contaminated objects. The Star of Chile described Chilean cities’ problematic hygiene: "filth is everywhere. We eat it, drink it, and breathe it."

Even as smallpox still raged out of control, plague also invaded every corner of Chile cities. Dirty houses and streets allowed rodents like the black, brown, and Hanoverian or sewer rat to act as disease vectors. Plague patients developed fever and headache, as well as swollen and painful lymph nodes. The symptoms were commonly severe and often fatal.

A town in Chile called Pisagua, with an initial population of 25,000 people, had only 500 left after the plague swept past, probably owing to the wretched housing available to working people, who lived crammed together in conditions that facilitated the rapid spread of disease to all who worked and lived nearby.


Chilean Institute of Hygiene from Chilean National Museum of History (Santiago, Chile), 1900. Retrieved from http://www.memoriachilena.gob.cl/602/w3-article-77198.html. Accessed July 22, 2020. No Copyright - United States.

Environmental factors in disease transmission