Table 2. Clinical features and histories of patients with positive POWV IFA assay results, Wisconsin, July–August 2015*.
| Patient no. | POWV test results | Borrelia burgdorferi test results† | Clinical features | Comorbidities | CDC case classification | Travel history | Location of tick exposure‡ | Vaccine history§ |
|---|---|---|---|---|---|---|---|---|
| Suspected TBD patients | ||||||||
| 1¶ | IgG >1:40 | IgG and IgM | 56-year-old man with 2-wk history of erythema migrans. Treated with doxycycline for 14 d. | Metabolic syndrome, hypertension, 9 y previous had WNV infection | – | Midwest | – | |
| 2 | IgG >1:40, PRNT 1:160 | IgG and IgM | 53-year-old man with 3-d history of urticarial rash, malaise, fever, and fatigue. Patient had chills 3 wks prior that resolved. CBC results: leukocytes 7.3 × 109/L, Hb 13.6 g/dL, Hct 39.9%, Plt count 322 × 103/µL; CRP 3.9 nmol/L. PCR neg for Anaplasma sp., Babesia sp., and Ehrlichia muris. Treated with doxycycline for 21 d with complete resolution of symptoms. No history of neuroinvasive disease or TBD. | Hyperlipidemia | – | – | – | |
| 3 | IgM >1:20 | IgG and IgM | 14-year-old girl with 3-d history of urticarial rash. CBC results: leukocytes 8.8 × 109/L, Hb 13.0 g/dL, Hct 40.3%, Plt 393 × 103/µL; CRP 3.6 nmol/L. Treated with doxycycline for 14 d. | None | – | – | – | |
| 4 | IgM >1:20 | IgG and IgM | 4-year-old girl with 1-wk history of fever (103°F), listless, headache, fatigue, and maculopapular rash. PCR neg for Anaplasma sp., Babesia sp., and Ehrlichia muris. Treated with amoxicillin for 21 d. | None | Probable | – | – | – |
| 9 |
IgM >1:20 |
IgG and IgM |
3-year-old girl with 1-wk history of intermittent fever, fussiness, and erythema migrans. After development of an urticarial rash, treatment with cefuroxime was changed to amoxicillin for 21 d. |
None |
Probable |
– |
Midwest |
– |
| Patients screened by chemical methods | ||||||||
| 1c | IgG >1:40 | Neg | 68-year-old man with no signs or symptoms of acute infectious disease. No history of neuroinvasive disease or TBD. Died from liver cirrhosis. | Coronary artery disease, liver cirrhosis, end stage renal disease | – | – | – | |
| 2c | IgM >1:20, IgG >1:40 | Neg | 76-year-old woman with 2-d history of fever, chills, and MRSA infection of the right hand. Mild abdominal pain and diarrhea occurred later in course. CBC results: leukocytes 13.7 × 109/L, Hb 9.2 g/dL, Hct 29.7%, Plt 180 × 103/µL; CRP 1.5 nmol/L; Procalcitonin 0.1 µg/L. Received daptomycin for 16 d with full recovery. Currently deceased, unknown cause of death. | Congestive heart failure, rheumatoid arthritis on immune-suppressive medications | Probable | – | – | – |
*CBC, complete blood cell count; CDC, Centers for Disease Control and Prevention; CRP, C-reactive protein; Hb, hemoglobin; Hct, hematocrit; IFA, immunofluorescence antibody; MRSA, multidrug-resistant Staphylococcus aureus; neg, negative; Plt, platelet; POWV, Powassan virus; PRNT, plaque reduction neutralization test; WNV, West Nile virus; TBD, tickborne disease; –, no history. †Samples were screened by EIA and followed up by Western blot. ‡Patient-reported tick exposure. §Known history of vaccination against yellow fever virus, Japanese encephalitis virus, or tick-borne encephalitis virus. ¶Cross-reactivity on POWV IgG IFA assay is consistent with a history of West Nile virus infection.