Abstract and Introduction
Tickborne relapsing fever (TBRF) is a bacterial infection caused by certain species of Borrelia spirochetes and transmitted through the bite of Ornithodoros ticks. Clinical illness is characterized by relapsing fever, myalgias, and malaise. On May 10, 2011, CDC and the Colorado Department of Public Health and Environment were notified of two patients with TBRF: a young woman and her newborn child. This report summarizes the clinical course of these patients and emphasizes the importance of considering a diagnosis of TBRF among patients with compatible clinical symptoms and residence or travel in a TBRF-endemic area. Pregnant women and neonates are at increased risk for TBRF-associated complications and require prompt diagnosis and treatment for optimal clinical outcomes. Public health follow-up of reported TBRF cases should include a search for persons sharing an exposure with the patient and environmental investigation with remediation measures to prevent additional infections.
On May 2, 2011, a previously healthy woman aged 24 years sought treatment at a local emergency department in Colorado after 1 week of fever, nausea, headache, stiff neck, and occasional blurred vision. Approximately 20 hours earlier, she had delivered a newborn (at 39 weeks' gestation) in a mountain cabin, without medical attendance. She had received limited prenatal care. Delivery was notable for amniotic fluid discoloration consistent with meconium. Physical examination revealed an ill-appearing and afebrile woman with hypotension (blood pressure: 70/40 mmHg). Gynecologic examination was unremarkable. A complete blood count revealed an elevated white blood cell count of 18,000/µL (normal: 4,500–10,000/µL), a decreased hematocrit of 30% (normal: 37%–47%), and a decreased platelet count of 42,000/µL (normal: 130,000–400,000/µL). Blood chemistries were remarkable for an elevated creatinine of 1.6 mg/dL (normal: 0.6–1.3 mg/dL), elevated aspartate aminotransferase of 61 IU/L (normal: 15–37 IU/L), and elevated alkaline phosphatase of 422 IU/L (normal: 50–136 IU/L). She was admitted and treated empirically using intravenous piperacillin with tazobactam for postpartum sepsis and fluid resuscitation for hypotension. Antibiotics were changed to oral amoxicillin after 48 hours. A blood culture drawn at admission revealed no growth, and the patient remained afebrile during hospitalization. Because of worsening anemia, she was transfused with packed red blood cells on May 3. Her condition improved, and she was discharged on May 5.
The newborn female accompanied her mother to the emergency department on May 2. Although physical examination was normal, the newborn was admitted for observation. An initial complete blood count was unremarkable, and blood culture collected at admission had no growth after 5 days. The patient developed neonatal jaundice on May 4 and remained hospitalized. On May 7, she became febrile with a temperature of 101.2°F (38.4°C) and had a platelet count of 34,000/µL (normal: 130,000–400,000/µL). Blood chemistries revealed an elevated alkaline phosphatase of 196 IU/L (normal: 50–136 IU/L) and a decreased albumin of 2.4 g/dL (normal: 3.4–5.0 g/dL). Treatment for sepsis was initiated with administration of gentamicin, ampicillin, and acyclovir. Subsequently, her platelet count decreased further to 14,000/µL. A review of the peripheral blood smear to evaluate the newborn's thrombocytopenia incidentally revealed spirochetes consistent with TBRF (Figure). A 10-day course of intravenous penicillin-G and platelet transfusions for progressive thrombocytopenia were initiated. The newborn recovered and was discharged on May 20. Because of the newborn's spirochetemia, the mother was presumptively treated for TBRF with doxycycline.
Stained thin smear of a newborn's peripheral blood, showing the presence of numerous spirochetes (indicated by black arrows) at 63X magnification — Colorado, 2011
Blood and serum samples from the mother and her newborn were tested by CDC's Bacterial Diseases Branch, Fort Collins, Colorado. Presence of spirochetes was visually confirmed from the newborn's blood smear prepared May 7; a whole blood sample collected the same day yielded evidence of relapsing fever Borrelia species by polymerase chain reaction. Sequencing of polymerase chain reaction targets revealed 100% match to Borrelia hermsii. Testing of the newborn's serum also obtained May 7 did not detect B. hermsii antibodies by either enzyme immunoassay (EIA) or immunoglobulin M (IgM) and immunoglobulin G (IgG) Western immunoblots. A sample collected from the newborn 3 days later had equivocal results by EIA and three bands visible on IgM immunoblot and one band visible on IgG immunoblot. Serum collected from the mother on May 13 produced a positive B. hermsii EIA, >10 bands by IgM immunoblot, and 10 bands by IgG immunoblot. The mother's clinical history and dominant IgM antibody response supported acute maternal B. hermsii infection acquired during the weeks preceding delivery; the limited antibody response by the newborn also supported a diagnosis of acute TBRF infection.
The mother was not employed and had moved from a densely populated urban area in Colorado to the previously vacant cabin 18 days before delivery. This rural Colorado cabin was situated near the base of a mountain range within a juniper and piñon tree forest at an approximate elevation of 8,800 feet. The single-room structure lacked electricity and running water. An environmental assessment indicated no ongoing rodent activity, and no ticks were recovered. The cabin owner declined to permit access to internal wall spaces to search for rodent nests.
Morbidity and Mortality Weekly Report. 2012;61(10):174-176. © 2012 Centers for Disease Control and Prevention (CDC)