What is the fine-grained topic of the following text: Data were extracted for 2004-2014 from a public health communicable disease database that contained data on patients under investigation for B. pertussis (both those who had laboratory tests and those who were epidemiologically linked to laboratory-confirmed cases) in Alberta, Canada. Only return the topic.
Investigation of B. pertussis cases in Alberta, Canada from 2004-2014 using a communicable disease database.