Clinical Consultation: Another reason to take tick bites seriously: Risk of multiple infections

While acute Q fever can cause pneumonia and other febrile illnesses, it is often asymptomatic. You may want to consider testing for Q fever if a patient is infected with another tick-borne pathogen, according to a report by Rolain and associates. They described 6 patients infected with organisms such as Rickettsia conorii who also were infected with Coxiella burnetii, the cause of Q fever.

The patients' presenting signs and symptoms are shown in the Table. None of them had a history or clinical presentation that suggested acute Q fever, but serologic testing confirmed this infection in all 6. Dual infections with tick-borne pathogens were confirmed by Western blot analysis after cross-adsorption studies. The identified pathogens included R conorii,Rickettsia africae, Rickettsia slovaca, and Francisella tularensis. The infections were thought to be concomitant in 3 patients and consecutive in 3.

The authors note that different bacteria can infect the same tick species, so a tick bite can result in infection with more than one organism. They recommend that patients infected with tick-borne pathogens be tested for concurrent infection with C burnetii.