Final answer:
The symptoms described are consistent with Q fever, caused by the bacterium Coxiella burnetii and primarily transmitted through inhalation of contaminated farmyard aerosols. It is an occupational disease of farmers.
Step-by-step explanation:
The symptoms described in the question, including diurnal fever that peaks in the evening and during the night but subsides during the daytime, are consistent with Q fever. Q fever is caused by the bacterium Coxiella burnetii and is primarily transmitted to humans through inhalation of contaminated farmyard aerosols. It is largely an occupational disease of farmers and is associated with exposure to domesticated livestock such as cattle, sheep, and goats.