translation.da: Kopper er en systemisk sygdom, der officielt har været udryddet siden 1979. Den skyldes infektion med Variola major-viruset, der havde mennesker som eneste smittereservoir.
translation.en: Smallpox was a systemic disease, officially eradicated since 1979, caused by infection with the Variola major virus, whose only reservoir was infected humans.