I think the new book I saw thta discussed Siptah and polio was:
Mummies and Death in Egypt, Françoise Dunand and Roger Lichtenberg. Cornell University Press, 2006.
If I recall correctly this book also mentioned the disease that Ramses V suffered from was probably small pox. Ramses V is the Egyptian identity of Esarhaddon and the Greek Orestes (who was plagued by the Erinnyes). Recall that Orestes was the son of Agamemnon (Tiglath-pileser III).
Mummy of Ramses V
Ramses V and Small Pox
(scroll down to section on Ramses V)
(other rulers killed by small pox)
Ramses V and Siptah
(this page discusses the small pox of Ramses V and the polio of Siptah)
© Charles N. Pope, US Library of Congress. All rights reserved.