The conductor's management in Amsterdam, via the Dallas Symphony press office, confirmed that van Zweden recently injured his hip; doctors have prescribed a series of cortisone injections and complete rest.
The NZSO engagement was for a four-city tour of the country's North Island with piano soloist Freddy Kempf from May 10 through 19; the two programs include an all-Beethoven concert (the Fourth Piano Concerto and Fifth Symphony), and Prokofiev's Second Piano Concerto, Shostakovich's Fifth Symphony and the world premiere of New Zealand composer Lyle Cresswell's Alas! How Swift for trumpet and orchestra.
Securing a top-level maestro on short notice for a concert tour in the South Pacific is not easy, but the NZSO had a stroke of luck: Finnish conductor Pietari Inkinen — who has already worked with the orchestra twice (including making a recording for Naxos) and is returning this July — is in Australia this week, conducting the Queensland Orchestra in music by Beethoven and (as it happens) the Shostakovich Fifth Symphony. While in the (distant) neighborhood, he has agreed to fill in for van Zweden in New Zealand.
The Melbourne Symphony hasn't yet announced a replacement for van Zweden. Those concerts, from May 24 to 26, feature Prokofiev's Symphony-Concerto for Cello and Orchestra (with soloist Gautier Capu‹on) and Mahler's Symphony No. 4 (with soprano Celeste Lazarenko).
In addition to his new Dallas post, van Zweden is Chief Conductor and Artistic Director of the Netherlands Radio Philharmonic Orchestra and Radio Kamer Filharmonie; in 2008-09, the same season he begins his music directorship in Dallas, he takes over as principal conductor of the Royal Flanders Philharmonic Orchestra (deFilharmonie) in Antwerp.