Ehrlichiosis

3/05/2003

Question: What are aspects of human ehrlichiosis in the United States?

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Unique Identifier:11931023

Authors: Fang QQ. Mixson TR. Hughes M. Dunham B. Sapp J.

Institution: Department of Biology, Georgia Southern University,Statesboro 30460-8042, USA. qfang@gasou.edu

Title: Prevalence of the agent of human granulocytic ehrlichiosis in Ixodes scapularis (Acari: Ixodidae) in the coastal southeastern United States.

Source: Journal of Medical Entomology. 39(2):251-5, 2002 Mar.

Abstract: Human granulocytic ehrlichiosis (HGE) is an emerging tick-borne disease recently recognized in the United States. The blacklegged tick, Ixodes scapularis Say, is the principle vector in the eastern United States. The disease has been commonly reported in the northeastern and upper midwestern states; however, suitable vectors and reservoir hosts exist in the southeast. To assay the prevalence of the HGE agent in vector ticks, we screened 818 individual I. scapularis from 15 locations in South Carolina, Georgia, and Florida using nested polymerase chain reaction, which targets the HGE agent 16S rRNA gene. Prevalence among locations ranged from 0 to 20%. The overall average prevalence of 15 sites was 1.6% (n = 818). Verification by sequencing the 16S rDNA from the positive samples showed 99.8-100% nucleotide identities with the sequences of the HGE agent in GenBank. These results were supported by the phylogenetic analysis using 16S rDNA sequences. CAS Registry/EC Number 0 (RNA, Bacterial). 0 (RNA, Ribosomal, 16S).

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Unique Identifier:9986812

Authors: Comer JA. Nicholson WL. Olson JG. Childs JE.

Institution: Viral and Rickettsial Zoonoses Branch, National Center for Infectious Diseases, U.S. Department of Health and Human Services, Atlanta, Georgia 30333, USA. jncO@cdc.gov

Title: Serologic testing for human granulocytic ehrlichiosis at a national referral center.

Source: Journal of Clinical Microbiology. 37(3):558-64, 1999 Mar.

Abstract: An indirect immunofluorescence assay (IFA) was used to identify patients with antibodies reactive to the human granulocytic ehrlichiosis (HGE) agent. Serum samples collected from clinically ill individuals were submitted to the Centers for Disease Control and Prevention by physicians via state health departments from throughout the United States and tested against a panel of ehrlichial and rickettsial pathogens. Antibodies reactive to the HGE agent were detected in 142 (8.9%) of 1,602 individuals tested. There were 19 confirmed and 59 probable (n = 78) cases of HGE as defined by seroconversion or a fourfold or higher titer to the HGE agent than to the Ehrlichia chaffeensis antigens. The average age of patients with HGE was 57 years, and males accounted for 53 (68%) of the patients. Cases of HGE occurred in 21 states; 47 (60%) of the cases occurred in Connecticut (n = 14), New York (n = 18), and Wisconsin (n = 15). Onset of HGE was identified from April through December, with cases peaking in June and July. The earliest confirmed cases of HGE occurred in 1987 in Wisconsin and 1988 in Florida. No fatalities were reported among the 78 patients with confirmed or probable HGE. Reactivity to the HGE agent and to either Coxiella burnetii, Rickettsia rickettsii, or Rickettsia typhi was infrequent; however, 74 (52%) of the 142 individuals who were positive for HGE had at least one serum sample that also reacted to the E. chaffeensis antigen. Thirty-four persons with confirmed or probable human monocytic ehrlichiosis due to E. chaffeensis also had antibodies to the HGE agent in at least one serum sample. The specific etiologic agent for 30 patients was not ascribed because of similarity of titers to both ehrlichial antigens. The use of both antigens may be required to correctly diagnose most cases of human ehrlichiosis, especially in geographic regions where both the HGE agent and E. chaffeensis occur. CAS Registry/EC Number 0 (Antibodies, Bacterial). 0 (Antigens, Bacterial).

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Unique Identifier:8604172

Authors: Bakken JS. Krueth J. Wilson-Nordskog C. Tilden RL. Asanovich K. Dumler JS.

Institution: Section of Infectious Diseases, Duluth Clinic Ltd, MN 55805, USA.

Title: Clinical and laboratory characteristics of human granulocytic ehrlichiosis.

Source: JAMA. 275(3):199-205, 1996 Jan 17.

Abstract: OBJECTIVE--To characterize the clinical and laboratory features observed in patients with human granulocytic ehrlichiosis (HGE) and evaluate the utility of the diagnostic tools used to confirm the diagnosis. DESIGN--Retrospective case study of 41 patients with laboratory-diagnosed HGE. SETTING--A total of 228 patients from Minnesota and Wisconsin were evaluated between June 1990 and May 1995. METHODS--Cases were presumptively identified by a history of an influenzalike illness acquired in an area known to be endemic for ticks. Diagnostic laboratory testing included microscopic examination of Wright-stained peripheral blood smears for presence of neutrophilic morulae, polymerase chain reaction (PCR) analysis of acute-phase blood samples for the Ehrlichia phagocytophila/Ehrlichia equi group DNA, and evaluation of serological responses by indirect immunofluorescent antibody assay (IFA), using E equi as antigen. RESULTS--All patients presented with a temperature of at least 37.6 degrees C, and most had headache, myalgias, chills, and varying combinations of leukopenia, anemia, and thrombocytopenia. Eighty percent of the patients tested demonstrated morulae in the cytoplasm of peripheral blood neutrophils. Only 16 of 37 patients tested by PCR were positive for HGE, whereas serum IFA assays of acute or convalescent blood samples detected antibodies against E equi in 38 of 40 patients tested. Two patients died, and the calculated case fatality rate was 4.9%. CONCLUSIONS--Human granulocytic ehrlichiosis is being increasingly recognized in Wisconsin and Minnesota. A more severe illness is associated with increased age, anemia, increased percentage of neutrophils and decreased percentage of lymphocytes in peripheral blood, and presence of morulae in neutrophils. The differential diagnosis for patients who develop an influenzalike illness following a tick bite should include HGE. Microscopic examination of the acute-phase blood smear to detect neutrophilic morulae is currently the quickest and most practical screening method for diagnosing HGE in the upper Midwest. CAS Registry/EC Number 0 (DNA, Bacterial).

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Unique Identifier:8147546

Authors: Fishbein DB. Dawson JE. Robinson LE.

Institution: National Center for Infectious Diseases, Atlanta, Georgia.

Title: Human ehrlichiosis in the United States, 1985 to 1990.

Source: Annals of Internal Medicine. 120(9):736-43, 1994 May 1.

Abstract: OBJECTIVE: To describe the epidemiology, clinical features, laboratory manifestations, response to therapy, and factors related to morbidity and mortality in a large group of patients with ehrlichiosis. DESIGN: Case-series. SETTING: Laboratory-based surveillance in the United States. PATIENTS: 237 patients whose serum had a fourfold increase or decrease in antibodies to Ehrlichia canis or E. chaffeensis. MEASUREMENTS: Epidemiologic, clinical, laboratory data, hospitalization, duration of illness, complications, and treatment response. RESULTS: From 1985 through 1990, 237 case-patients were identified in 21 states; rates exceeded 1 per 100,000 per year in only 5 counties. Incidence rates increased with age and were higher among men. Most case-patients had nonspecific illness and were not suspected of having a rickettsial infection. Many patients (60.8%) were hospitalized. Leukocyte and platelet counts typically decreased and liver function tests typically increased through day 7. Three (6.1%) of 49 outpatients treated only with tetracycline were hospitalized compared with 35 (92%) of 38 outpatients treated only with antibiotics other than tetracycline or chloramphenicol (P < 0.001). Among hospitalized patients, recovery was faster for those initially treated with tetracycline (median, 16 days) or chloramphenicol (median, 12 days) than for those initially treated with other antibiotics (median, 27 days; P = 0.03 for both comparisons). In a logistic regression analysis, severe illness or death was more probable among case-patients 60 years or older (odds ratio [OR], 4.60; 95% CI, 1.87 to 11.2) and among those who did not receive tetracycline or chloramphenicol until 8 or more days after symptom onset (OR, 4.38; CI, 1.36 to 14.0). CONCLUSIONS: The findings of this study are primarily representative of more seriously ill patients with human ehrlichiosis. Although rates are low, ehrlichiosis is found in many areas of the United States. Patients with a history of tick exposure, acute febrile illness, decreasing leukocyte counts, and decreasing platelet counts may have ehrlichiosis. Prompt treatment with tetracycline or chloramphenicol markedly decreases the morbidity. CAS Registry/EC Number 56-75-7 (Chloramphenicol). 60-54-8 (Tetracycline).