Human granulocytic ehrlichiosis (HGE) was first

Transcription

1 Human Granulocytic Ehrlichiosis: A Case Series from a Medical Center in New York State Maria E. Aguero-Rosenfeld, MD; Harold W. Horowitz, MD; Gary P. Wormser, MD; Donna F. McKenna, RN, CANP; John Nowakowski, MD; Jose Munoz, MD; and J. Stephen Dumler, MD Background: Human granulocytic ehrlichiosis (HGE) is a newly described illness with few reports in the literature. Objective: To describe the clinical and laboratory features of HGE. Design: Case series. Setting: Tertiary care facility in New York State. Patients: 18 adult patients with HGE. Measurements: Epidemiologic, clinical, and laboratory features; treatment; and outcome of patients with HGE. Results: Patients presented with such symptoms as fever (94%) and myalgia or arthralgia (78%). Thirteen patients (71%) recalled being bitten by a tick before onset of symptoms. Leukopenia or thrombocytopenia was seen in 82% of patients, and abnormal liver enzyme levels were seen in 81%. Results of polymerase chain reaction were positive in 9 of 12 patients (75%); morulae were seen in 3 of 12 patients (25%); and the agent that causes HGE was cultured from 2 patients. All but one patient (94%) developed antibodies to Ehrlichia equi. Five patients (28%) were briefly hospitalized, and none died. All patients were successfully treated with doxycycline. Conclusions: The illness associated with HGE in these patients from the northeastern United States was more mild than that originally described in reports of HGE in the midwestern United States. Ann Intern Med. 1996;125: From New York Medical College and Westchester County Medical Center, Valhalla, New York; and The Johns Hopkins Medical Institutions, Baltimore, Maryland. For current author addresses, see end of text. Human granulocytic ehrlichiosis (HGE) was first described in 1994 by Bakken and colleagues (1) in 12 patients from the midwestern United States. This report was followed by a retrospective case study (2) of 41 patients from the same geographic area. The data from these studies and from isolated case reports from several locations in the northeastern United States have been the only descriptions of the clinical and laboratory manifestations of HGE to date (2-5). We describe the clinical and laboratory findings of 18 patients who received a diagnosis of HGE in 1994 or 1995 at a medical center in a populous area in the suburbs of New York City. Patients Methods Patients were evaluated at the Westchester County Medical Center in 1994 and 1995; one patient (patient 18) has been discussed in another report (6). At the first visit, samples of blood were obtained for complete blood cell count, differential count, chemistry profile, buffy-coat smear for examination of morulae, polymerase chain reaction (PCR) assay for HGE, and serologic examination to test for presence of antibodies to Ehrlichia equi and E. chaffeensis. Blood samples were also collected during the first to sixth weeks of convalescence. Laboratory Testing Buffy-coat smears were stained with Wright stain, and at least 1000 granulocytes were microscopically examined for Ehrlichia morulae. The presence of antibodies was tested for by indirect immunofluorescent antibody assay using horse granulocytes infected with E. equi at an initial serum dilution of December 1996 Annals of Internal Medicine Volume 125 Number 11

2 1:80 as described elsewhere (1). We tested for antibodies to E. chaffeensis by using immunofluorescent antibody assay with infected DH82 cells (1, 7). Peripheral blood was tested by PCR using EDTAanticoagulated blood and the primer pair GE9f/ GElOr as described elsewhere (8). Samples of EDTA-anticoagulated blood from two patients (patients and 15) were inoculated into an HL-60 cell line for culturing as described elsewhere (9). Statistical Analysis The two-tailed Student Mest, Pearson correlation (SPSS software, Chicago, Illinois), and two-tailed Fisher exact test (EPISTAT software, Richardson, Texas) were used for data analysis. Results Eighteen patients received a diagnosis of HGE (3 in 1994 and 15 in 1995) in the Westchester County Medical Center. Most of these patients (83%) presented between June and August. Sixteen patients resided in Westchester County, and 2 resided in Putnam County; these counties are contiguous and located slightly north of New York City. Thirteen patients (72%) reported that they had been bitten by a tick: Four ticks were positively identified as Ixodes scapularis (three nymphs and one adult tick). The other nine patients who reported a tick bite described a tick whose appearance was compatible with that of /. scapularis. Symptoms appeared an average of 5.5 days after patients received the tick bite (Table 1). Two patients, neither of whom recalled being bitten by a tick, described a rash that they characterized as erythematous, pruritic, localized, and smaller than 5 cm in diameter. The described rash was not visible when these patients first visited the medical center. Patients were evaluated an average of 4.7 days after onset of symptoms (median, 3 days [range, 1 to 15 days]). Five patients (28%) required hospitalization for an average of 5 days. One patient (patient 15) was briefly admitted to an intensive care unit. None of the 18 patients died. Laboratory test results frequently showed leukopenia or thrombocytopenia and abnormal liver enzyme levels (Table 2). Lymphopenia (defined as <1.5 X 10 3 lymphocytes/jlil) was seen in 8 of 13 (62%) patients, and neutropenia (defined as <2 X 10 3 neutrophils/jul) was seen in 3 of 13 (23%). Lymphopenia was seen in 8 of 9 (89%) patients who presented with an illness that lasted 4 days or less and in none of 4 patients with an illness that lasted 5 days or longer (P = 0.006). Neutropenia was seen in 3 of 4 (75%) patients who had HGE for longer than 4 days but in only 1 of 9 (11%) patients who had the disease for 4 days or less (P = 0.05). Pearson correlation analysis showed that the initial neutrophil count was inversely related to the duration of symptoms before the first visit (r = [95% CI, to ]; P = 0.038) and that the lymphocyte count was directly related to the duration of symptoms before the first visit (r = [CI, to 0.836]; P = 0.055). Patients who had HGE for longer than 4 days usually had atypical lymphocytosis of at least 10% of the differential count. No patients had elevated serum creatinine or blood urea nitrogen levels, and only one patient had a low hemoglobin level. Leukocyte and platelet counts returned to normal during observation in all patients who received treatment; these values generally returned to normal earlier than did liver enzyme levels. Intracytoplasmic morulae were seen in 3 of 12 patients (25%). The frequency of infected granulocytes ranged from 0.3% to 6% (Table 2), and morulae were mostly seen in neutrophils (patient 15 had morulae in eosinophils). The presence of morulae correlated with age: Three of 4 patients older than 50 years of age and 0 of 8 patients younger than 50 years of age had morulae that could be detected. Results of polymerase chain reaction assay for HGE were positive in 9 of 12 patients (75%). All but 1 patient developed antibodies to E. equi. Three patients showed antibodies to E. chaffeensis in convalescent-phase specimens that had a higher titer (>2560) to E. equi. The HGE agent grew in the HL-60 cell line from the blood of 2 patients (patients and 15) who presented with HGE in the autumn of All 18 patients received doxycycline therapy, beginning an average of 13.2 days (median, 6 days [range, 1 to 78 days]) after the onset of symptoms (Table 1). Seven patients were initially treated with other antimicrobial agents. The therapy of 2 patients was changed from amoxicillin to doxycycline within 2 days of treatment. The other 4 patients, who were initially treated with amoxicillin, had recurrent fever or persistence of symptoms after 1 to 2 weeks of therapy; for these patients, therapy was changed to doxycycline. Symptoms resolved in all patients 24 to 48 hours after the start of treatment with doxycycline, which was administered for an average of.2 days (range, 1 to 21 days). No symptoms have been seen after follow-up as long as 1 year. Discussion We describe 18 adult patients with HGE from the northeastern United States. Symptoms in these patients developed an average of 5.5 days after a 1 December 1996 Annals of Internal Medicine Volume 125 Number

3 presumed or proven bite from an Ixodes tick and frequently included fever (body temperature >38.3 C), arthralgia and myalgia, and headache. Compared with the patients from the midwestern United States studied by Bakken and colleagues (1, 2), our patients were significantly younger (mean age ± SD, 47 ± 16 years compared with 57 ± 20 years; P = 0.04) and presented with a milder illness based on clinical and laboratory evaluations. Compared with the patients in our study, more midwestern patients were hospitalized (54% of midwestern patients compared with 28% in our study) and died (5% of midwestern patients compared with 0% in our study). Differences in case referral or in the threshold for diagnostic testing may explain some of these disparities. Although HGE has a nonspecific clinical presentation, abnormal results on certain routine laboratory tests considerably narrow the differential diagnosis. A diagnosis of Lyme disease may be considered in a patient with fever after a bite from /. scapularis, but cytopenia is extremely rare in that disease (10). In contrast, approximately 80% of our patients with HGE had leukopenia or thrombocytopenia. The explanation for these abnormal hematologic values and for abnormal liver enzyme levels is not yet known. Leukopenia can be caused by lymphopenia or neutropenia, with lymphopenia in the early stages of infection, followed by lymphocytosis with atypical lymphocytes. Among the methods for specifically diagnosing HGE, microscopic detection of morulae is the quickest; for our patients, however, this method lacked sensitivity. Morulae were seen in 3 of 12 patients (25%) in our series compared with 80% of the midwestern patients. Visualization of intragranulocytic inclusions is probably an indication of massive infection and has been described as a risk factor, along with older age, for more serious illness (2). In our series, PCR was the most sensitive diagnostic test during the acute phase. Nine of 12 (75%) of our patients had positive PCR results compared with 43% in the midwestern series (2). As suggested by Bakken and colleagues, the lower sensitivity may have been caused by poor preservation of specimens and conditions that were suboptimal for the PCR assay. Another diagnostic approach that offers definitive evidence of infection is isolation of the organism in culture (9). In our study, culture was done for two patients in whom morulae were seen in peripheral blood granulocytes; Ehrlichia was isolated in both Table 1. Demographic Characteristics, Chronology, Clinical Presentation, and Treatment of 18 Patients with Human Granulocytic Ehrlichiosis* Patient Age Sex Time from Time from Signs and Symptoms Treatment Duration of Tick Bite to Symptom Treatment Symptom Onset to Fever Headache Stiff Myalgia or Chills Other Onset Therapy Neck Arthralgia y d d 1 29 Female Amoxicillin Amoxicillin 2 34 Male Dizziness, diarrhea Amoxicillin 3 48 Female Male Male NA Syncope, rash Amoxicillin Male Amoxicillin 7 54 Male Diarrhea 8 64 Female NA Female Female Diarrhea, nausea Male Sore throat Female Dizziness Female NA Rash Amoxicillin 74 Male Anorexia Male NA 7 + ~ Chest pain Cephalosporins Male Male NA Backache Male Brachial plexopathy Amoxicillin Cephalosporins * Mean patient age ± SD, 47 ± 16 years. Symptoms started a mean of 5.5 ± 3.5 days after tick bite. Therapy with doxycycline was begun a mean of 13.1 ± 18.9 days after onset of symptoms. Among all patients, 94% presented with fever, 78% with headache, 22% with stiff neck, 61% with myalgia or arthralgia, and 44% with chills. A plus sign indicates that a patient had a given symptom or sign; a minus sign indicates that the patient did not have a given symptom or sign. NA = not available December 1996 Annals of Internal Medicine Volume 125 Number 11

4 Table 2. Laboratory Variables during Acute and Convalescent Phases of Human Granulocytic Ehrlichiosis* Patient Duration of Time of Leukocyte Platelet AST Level ALT Level LDH Level Result of Result of Poly Immuno- Immuno- Disease Visit Count Count Test for merase Chain Morulaet Reaction* o 7 x Kf/L < U/L > fluorescent Antibody Titer for Ehrlichia equi fluorescent Antibody Titer for E. chaffeensis Negative ND <80 < Negative Positive 2> ND ND ND ND 1280 < Negative Positive 1280 < ND ND 1280 < Negative Positive <80 < ND ND 320 < Negative Positive <80 < ND ND 640 < Negative Positive <80 < ND ND ND ND ND ND ND 18 ND ND ND ND 640 < ND ND 160 < ND ND ND ND 27 ND ND ND ND 1280 < Positive Positive ND ND Negative Negative 2= ND ND >2560 < ND ND ND Negative Negative 640 < Negative Positive <80 < ND ND 2=2560 < Negative Negative <80 < ND ND 320 < Negative Negative <80 < ND ND ND ND ND 160 < ND ND ND ND Negative Negative <80 < ND ND ND ND ND 2=2560 < ND ND ND ND ND ND 2=2560 < Positive Positive <80 < ND ND ND ND ND ND ND ND ND <80 < ND ND <80 < Positive^ ND ND ND Positive^] ND ND ND Positive Positive 2= Negative ND 2= ND ND ND ND ND ND ND 1280 < ND ND ND ND ND ND ND ND ND <80 <80 20 ND ND ND ND ND ND ND 2=2560 < ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 150 ND ND ND ND ND ND ND 640 <80 * Normal range for leukocyte count, 4.6 to 11.3 cells x 10 9 /L; for platelet count, 160 to 410 cells x 10 9 /L; for aspartate aminotransferase level, 4 to 35 U/L; for alanine aminotransferase level, 2 to 40 U/L; for lactate dehydrogenase level, 110 to 225 U/L. Abnormal values are in boldface. Immunofluorescence antibody titer represents the reciprocal of serum dilution. ALT = alanine aminotransferase; AST = aspartate aminotransferase; LDH = lactate dehydrogenase; ND = not done. t Patient 7 had 0.3% infected granulocytes, patient had 0.4%, and patient 15 had 6%. * Polymerase chain reaction was done using the primer pair GE9f/GE10r to the genomic group. Normal by outside testing laboratory. 11 Positive for morulae on retrospective analysis of blood smears. cases. However, this technique is probably not easily done in most clinical laboratories, and its sensitivity has not yet been determined. Detection of antibodies to E. equi by immunofluorescent antibody assay is useful for confirming the diagnosis of HGE, but often only in retrospect. During the acute phase of HGE, the results of immunofluorescent antibody assay were positive in only 29% of our patients and 23% of the patients in the midwestern cohort. Current serologic assays to detect antibodies to Ehrlichia, however, lack standardization. Although all but one patient (94%) in our series developed antibodies to E. equi, the sensitivity and specificity of serologic testing have not been defined. Because Bakken and colleagues (2) reported that E. equi antibodies persist for longer than 1 year in nearly 50% of persons with HGE, some background seroreactivity probably exists in highly endemic areas; this possibility should therefore be considered when patients are evaluated. Another potential source of diagnostic confusion is cross-reactivity between E. equi and E. chaffeensis (the agent of human monocytic ehrlichiosis). Three (17%) of our patients had antibodies to E. chaffeen- 1 December 1996 Annals of Internal Medicine Volume 125 Number

5 sis (2 in low titer) as did 3 (8%) of 40 midwestern patients (2) and another patient with HGE in Massachusetts who was described in another study (4). The practitioner must be aware that human monocytic ehrlichiosis and HGE are caused by distinct pathogens and that distinct diagnostic tests must therefore be requested for diagnosis to be confirmed or excluded. Patients with HGE respond clinically within 48 hours of treatment with tetracyclines; empirical treatment may thus be warranted when strong clinical suspicion exists. The optimal duration of therapy has not yet been established, but short courses may be as effective as longer ones. Because of intolerance to the drug, one of our patients received doxycycline for only 1 day, but clinical and laboratory evidence of infection nonetheless resolved. In the studies by Bakken and colleagues (1, 2), the symptoms of six (15%) patients completely resolved without specific treatment. Many cases of HGE may be subclinical and self-limiting, a phenomenon that has been well documented with human monocytic ehrlichiosis (11, 12). Tetracyclines are also excellent therapy for early Lyme disease, which is particularly important when Lyme disease alone, or as a coinfection with HGE, cannot be excluded (13). Our case series either represents a milder form of illness caused by the same pathogen that was described in the midwestern United States or reflects the clinical disease caused by a closely related organism that has different virulence properties. Only when diagnostic testing becomes more widely available and more reliable and when large patient samples are systematically studied will the true incidence and clinical spectrum of this potentially serious illness be understood. Note: The contents of this manuscript are solely the responsibility of the authors and do not represent the official views of the Centers for Disease Control and Prevention or the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Acknowledgments: The authors thank Eleanor Shields, Lois De- Lungo, Odile Levrat, Olga McDermott, Kristin Asanovich, Jen Walls, and Dan Edelman for their excellent technical assistance and Dan Byrne for statistical analysis. Grant Support: In part by Cooperative Agreement U50/CCU from the Centers for Disease Control and Prevention (Dr. Wormser), grants RO1-AR41508 (Drs. Nowakowski and Wormser) and R01-AR43135 (Dr. Wormser) from the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a Research Initiative Support Award by the University of Maryland School of Medicine, and Grant-in-Aid award BG2094 by the Maryland Chapter of the American Heart Association (Dr. Dumler). Requests for Reprints: Maria E. Aguero-Rosenfeld, MD, Clinical Laboratories, Room U-lla, Westchester County Medical Center, Valhalla, NY Current Author Addresses: Dr. Aguero-Rosenfeld: Clinical Laboratories, Room U-lla, Westchester County Medical Center, Valhalla, NY Drs. Horowitz, Wormser, and Nowakowski: Division of Infectious Diseases, Westchester County Medical Center, Macy Pavilion 209 SE, Valhalla, NY Ms. McKenna: Main Nursing Office, Westchester County Medical Center, Valhalla, NY Dr. Munoz: New York Medical College, Department of Pediatrics, Munger Pavilion Room 113, Valhalla, NY Dr. Dumler: Division of Medical Microbiology, Department of Pathology, Meyer Bl-193, The Johns Hopkins Medical Institutions, 600 North Wolfe Street, Baltimore, MD References 1. Bakken JS, Dumler JS, Chen SM, Eckman MR, Van Etta LL, Walker DH. Human granulocytic ehrlichiosis in the upper Midwest United States. A new species emerging? JAMA. 1994;272: Bakken JS, Krueth J, Wilson-Nordskog C, Tilden RL, Asanovich Kf Dumler JS. Clinical and laboratory characteristics of human granulocytic ehrlichiosis. JAMA. 1996;275: Human granulocytic ehrlichiosis New York, MMWR Morb Mortal Wkly Rep. 1995;44: Telford SR 3d, Lepore TJ, Snow P, Warner CK, Dawson JE. Human granulocytic ehrlichiosis in Massachusetts. Ann Intern Med. 1995;123: Hardalo G, Quagliarello V, Dumler JS. Human granulocytic ehrlichiosis in Connecticut: report of a fatal case. Clin Infect Dis. 1995;21: Horowitz HW, Marks SJ, Weintraub M, Dumler JS. Brachial plexopathy associated with human granulocytic ehrlichiosis. Neurology. 1996;46: Dumler JS, Asanovich KM, Bakken JS, Richter P, Kimsey R, Madigan JE. Serologic cross-reactions among Ehrlichia equi, Ehrlichia phagocytophila, and human granulocytic Ehrlichia. J Clin Microbiol. 1995;33: Edelman DC, Dumler JS. Evaluation of an improved PCR diagnostic assay for human granulocytic ehrlichiosis. Molecular Diagnostics. 1996;1: Goodman, JL, Nelson C, Vitale B, Madigan JE, Dumler JS, Kurtti TJ, et al. Direct cultivation of the causative agent of human granulocytic ehrlichiosis. N Engl J Med. 1996;334: Nadelman RB, Nowakowski J, Forseter G, Goldberg NS, Bittker S, Cooper D, et al. The clinical spectrum of early Lyme borreliosis in patients with culture-confirmed erythema migrans. Am J Med. 1996;100: Fishbein DB, Dawson JE, Robinson LE. Human ehrlichiosis in the United States, 1985 to Ann Intern Med. 1994;120: Petersen LR, Sawyer LA, Fishbein DB, Kelley PW, Thomas RJ, Magnarelli LA, et al. An outbreak of ehrlichiosis in members of an Army Reserve unit exposed to ticks. J Infect Dis. 1989;159: Wormser GP, Horowitz HW, Dumler JS, Schwartz I, Aguero-Rosenfeld M. False-positive Lyme disease serology in human granulocytic ehrlichiosis [Letter]. Lancet. 1996;347: American College of Physicians December 1996 Annals of Internal Medicine Volume 125 Number 11