Medieval diseases lurk in LA: 124 cases of Typhus are confirmed | Daily Mail Online
Fleas carry Typhus from infected stray animals. Though rats are most often attributed with the disease, any stray animal like cats or opossums can also be carriers
A brief history of typhus as a epidemic
Depiction of typhus outbreak in Byzantine Empire
Typhus – European History of Diseases
British Guard post at Belson Camp WWII
I really don’t think there is to much to add. Typhus is treatable and 124 cases (known and confirmed), if spread out over time, the local medical institutions SHOULD be able to handle it. You are talking about a population that mostly has a basic mistrust of government and may hide from treatment, thus spreading it even further.