Infectious disease and Rickettsial disease

Infectious disease noun - A disease transmitted only by a specific kind of contact.

Rickettsial disease and infectious disease are semantically related. In some cases you can replace phrase "Rickettsial disease" with "Infectious disease", this phrases are similar.

Rickettsial disease noun - Infectious disease caused by ticks or mites or body lice infected with rickettsial bacteria.

Infectious disease and rickettsial disease are semantically related. You can use "Infectious disease" instead a noun phrase "Rickettsial disease".