As 24th has posted there isnt any evidence of Small Pox being present in Natal or Zululand during the war . HMS Boadicea's cases were discovered when the ship was at Simon's Bay , which from memory is near Capetown ? , nowhere near Zululand .
I do remember reading the Boadicea was moored off -shore until the Small box was contained , the ship then setting sail to Durban and arriving after the start of the war , possibly March ? .