You’d think that it’s a two way street. We gave them disease by accident they gave us some. But I can’t really find any native disease that killed off Europeans like smallpox killed natives
Hi there -- not discouraging further answers, but this is a frequently asked question here on this subreddit.
Well, American natives certainly did their best to grace their conquerors with some local pests.
While syphilis did exist in Europe before the conquest of the Americas^1, with already attempts at treatment by mercury found in traces in several bone samples, and also did exist in the Americas^2, there is a relatively well accredited theory^3 in historical epidemiology that modern (and more virulent) syphilis was brought back from the Americas by the very first crews from Europe that went to the Caribbean (possibly the crews of Columbus). Extensive review papers and skeletal analysis document the "Columbian hypothesis" further^3b.
The first major outbreak of syphilis in Europe occured in Naples (a major harbour in mediterranean exchanges, in particular between Italy and Spain at the time) in 1494. As it occured during a French invasion it became known as the "mal français" (French disease) in Italian. This in turn gave its name to the "Petite France", a district in the city of Strasbourg where victims of this outbreak of the "French disease" were treated in a hospital^4.
Each country of Europe knows it as the disease from the country where it supposedly came : in Italy, Poland or Germany it is called (from the original Italian) the "French disease", the Dutch called it the "Spanish disease", the Russians called it the "Polish disease", and the Turks called it the "Christian disease". In French it is the "mal italien" (Italian disease) (e.g. in the Contes Drolatiques by Balzac : "Que le mal italien me délivre de ce meschant braguard à nez flatry".
Turns out it is an American disease.
^1 : Kaare Lund Rasmussen, Jesper Lier Boldsen, Hans Krongaard Kristensen, Lilian Skytte, Katrine Lykke Hansen, Louise Mølholm, Pieter M. Grootes, Marie-Josée Nadeau, Karen Marie Flöche Eriksen, « Mercury levels in Danish Medieval human bones », Journal of Archaeological Science, vol. 35, no 8, août 2006, p. 2295–2306 (DOI 10.1016/j.jas.2008.03.003).
^2 : Armelagos, George J. (2012), "The Science behind Pre-Columbian Evidence of Syphilis in Europe: Research by Documentary", Evol. Anthropol., 21 (2): 50–7, doi:10.1002/evan.20340, PMC 3413456 Freely accessible, PMID 22499439
^3 Farhi, D; Dupin, N (September–October 2010). "Origins of syphilis and management in the immunocompetent patient: facts and controversies". Clinics in Dermatology. 28 (5): 533–8. doi:10.1016/j.clindermatol.2010.03.011. PMID 20797514.
^3b : https://www.sciencedaily.com/releases/2011/12/111220134144.htm
^4 : Strasbourg insolite et secret, L. Maechel & T. Rieger, p. 74.