Johann Ewert was my 3rd great grandfather and I have heard the same story about his acquiring rabies from a wolf attack while on night duty in Rosenthal, Chortitza colony in 1861.Apparently his daughter Susanna wrote an account of this, but I have not been able to locate it.
Unfortunately I cannot add much to your current information.I, too, only know of two children: Johann and Susanna. Johann (my 2nd great grandfather) came to Manitoba in 1875 and died in 1893.How are you related to Johann Ewert?
According to a family tree prepared for a family member,his wife Susanna Sawatzky may have died from cholera 9 June 1855.Her parents were Gerhard Sawatzky (b 12 Jun 1781 in Danzig/d 30 April 1842 Rosenthal, Chortitza) and Agatha Friesen (b 8 Sept 1785 Tiefenhof, Gross Werder/d 21 Sept 1877 Rosenthal).
I'd love to know if you have found more information since 2005.