In August 2012, a previously healthy 34-year-old insect ecologist in her 31st week of pregnancy presented to an obstetrics clinic in Toronto, Ontario, with a 2-day history of fever, chills, nausea, vomiting and myalgia. Her symptoms had begun 2 days after returning from a camping trip in southern British Columbia.
She appeared unwell, with mild tachycardia and a maximum temperature of 38.4[degrees]C. Her physical examination was otherwise normal, and the results of initial laboratory investigations were within normal ranges. She was admitted to the obstetrics department with a presumed viral syndrome. An initial infectious workup included blood cultures, serologies for cytomegalovirus, HIV and parvovirus B19, and a nasopharyngeal swab for respiratory viruses.
Forty-eight hours after admission, her fever persisted, her platelet level decreased from 145 x [10.sup.9] to 27 x [10.sup.9]/L (normal 146-429 x [10.sup.9]/L), and her hemoglobin level decreased from 115 to 93 (normal 95-115) g/L. Thrombocytopenia prompted a routine peripheral blood smear, and spirochetes were shown by use of Wright stain (Figure 1).
A more detailed epidemiologic history showed that she had stayed in a farmhouse in Mission, BC, from July 7 to July 9; she had subsequently camped, hiked and swam in fresh water near Lillooet from July 9 to July 12, and had slept in a trailer near Kootenay Lake from July 17 to July 29. She recalled having mosquito bites but no tick bites or rashes. She returned to Ontario on July 31.
Presumed tick-borne relapsing fever was diagnosed, and erythromycin was started. The patient was transferred to the intensive care unit in case of a Jarisch-Herxheimer reaction (Box Within hours after starting antibiotics, her temperature rose to 38.5[degrees]C, and her heart rate increased to 150 beats/min. We consulted the hematology service, and after hemolysis, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura and HELLP (hemolysis, elevated liver enzymes, low platelets) syn drome were ruled out, she was given intravenous immunoglobulin therapy for possible immunemediated thrombocytopenia.
Over the following 24 hours, dyspnea, increased oxygen requirements requiring noninvasive positive pressure ventilation, and bibasilar crackles developed, and pulmonary edema was observed on a chest radiograph. Electrocardiography showed nonspecific ST depression, without a troponin rise. An echocardiogram showed left ventricular hypokinesis with an ejection fraction of 45% (normal 55%-70%) and a right ventricular systolic pressure of 40 (normal 15-30) mm Hg. Severe thrombocytopenia persisted despite the patient receiving 1 unit of pooled platelets and 2 doses of immunoglobulin administered intravenously. Her medication was then changed to intravenously administered ceftriaxone for possible myocarditis related to tick-borne relapsing fever and in case of co-infection with leptospirosis, given her exposure to fresh water. Doxycycline was added after a discussion of the risks and benefits of its use in pregnancy with the patient. Two doses of betamethasone were administered because of the risk of preterm birth, and furosemide was administered for diuresis.
By the eighth day in hospital, major improvement in the patient's hypoxia, fever, platelet count and overall clinical status were noted. Doxycycline was stopped after 4 doses, and erythromycin with ceftriaxone were...