Volume 25, Number 11—November 2019
Human Case of Ehrlichia chaffeensis Infection, Taiwan
In 2018, an immunosuppressed woman in southern Taiwan had onset of fever, chills, myalgia, malaise, thrombocytopenia, lymphocytopenia, and elevated hepatic transaminases. Investigation revealed infection with Ehrlichia chaffeensis. This autochthonous case of human monocytotropic ehrlichiosis was confirmed by PCR, DNA sequencing, and seroconversion.
Human monocytic ehrlichiosis (HME) is an acute, febrile, tickborne disease caused by the bacterium Ehrlichia chaffeensis. HME was first reported in the United States in 1986 (1), and >1,000 ehrlichiosis cases have been reported annually since 2012 (https://www.cdc.gov/ehrlichiosis/stats/index.html). In Asia, however, only a limited number of HME cases have been reported in 3 countries (Thailand, South Korea, and China) (2–4).
Clinical manifestations of HME range from mild febrile illness to severe multiple organ failure. The most common symptoms of HME are fever, headache, myalgia, malaise, nausea, vomiting, diarrhea, and abdominal pain (5–7), which are difficult to differentiate from the symptoms of other febrile infectious diseases. Therefore, HME must be confirmed by laboratory diagnosis.
Although HME has not been documented in Taiwan, serologic evidence of Ehrlichia spp. has been detected in small mammals, such as Rattus norvegicus, R. losea, and Bandicota indica rats that are found around international and local harbors (8). In addition, Haemaphysalis flava ticks infected with Ehrlichia spp. have been collected from pale thrush birds (Turdus pallidus) and identified in Taiwan (9). We report an autochthonous human case of E. chaffeensis infection in Taiwan.
In mid-July 2018, a 66-year-old woman living in the Namaxia District of Kaohsiung City in southern Taiwan was admitted to Kaohsiung Chang Gung Memorial Hospital with a 5-day history of intermittent fever (39.8°C), chills, myalgias, malaise, mild dyspnea, and diffuse abdominal pain. The patient had underlying hypertension, type 2 diabetes mellitus, alcoholic fatty liver, and gastroesophageal reflux disease. Laboratory examinations at admission showed that the patient had thrombocytopenia; lymphocytopenia; elevated levels of C-reactive protein, aspartate aminotransferase, alanine aminotransferase, and creatinine; and an increased number of polymorphonuclear leukocytes (Table). Whole blood counts were within reference ranges, and no leukocytopenia was observed. A chest radiograph showed mild infiltration over the bilateral lower lung fields. Laboratory tests for dengue, influenza A and B, hepatitis A, hepatitis B, and hepatitis C viruses were all negative. She was admitted under the impression of atypical infection and thrombocytopenia.
The patient is a coffee farmer who lives in a rural region in Kaohsiung. Although she claimed not to have received arthropod or animal bites, small mammals and birds had often been seen around her workplace and house. Therefore, arthropodborne rickettsial diseases were suspected, and oral doxycycline (100 mg every 12 h) for 4 days and intravenous ceftriaxone (1 g every 12 h) for 7 days were prescribed as empirical therapy on the patient’s first day at the hospital. Because ehrlichial infection had not been confirmed during hospitalization, the patient was discharged with a prescription (500 mg cefadroxil monohydrate every 12 h) to be taken for 5 days because of suspicion of atypical bacterial infection.
Blood specimens collected from the patient on day 6 (acute-phase specimens) and day 20 (convalescent-phase specimens) after illness onset were sent to the Taiwan Centers for Disease Control (Taipei, Taiwan) for laboratory diagnosis of zoonotic diseases. DNA extracted from acute-phase blood specimens using the QIAamp DNA blood Mini Kit (QIAGEN GmbH, https://www.qiagen.com) was used to detect Ehrlichia chaffeensis infection using a primer set targeting ehrlichial 16S rRNA gene (forward primer: AGCGGCTATCTGGTTCGA; reverse primer: CATGCTCCACCGCTTGTG) and an E. chaffeensis–specific primer set targeting the nitrogen assimilation regulatory protein (ntrX) gene (forward primer: TGCCGGTAGATATAGTATCGA; reverse primer: ATTTGCGATGAAGTGCGG) by QuantiNova SYBR green real-time PCR (QIAGEN). The PCR products of 16S rRNA (182 bp; GenBank accession no. MN088851) and the ntrX gene sequence (153 bp; GenBank accession no. MN096569) were determined and analyzed. The sequence was 100% homologous with the sequences of E. chaffeensis strains, including the Arkansas, Jax, Saint Vincent, West Paces, Wakulla, Osceola, Liberty, and Heartland strains. The PCR results were negative for Coxiella burnetii, Orientia tsutsugamushi, typhus group rickettsiae, spotted fever group rickettsiae, and Anaplasma phagocytophilum (Appendix Table). Paired (acute- and convalescent-phase) serum samples were used to detect antibodies against E. chaffeensis by using indirect immunofluorescence assay according to the manufacturer’s recommendation (Focus Diagnostics, https://www.focusdx.com). IgG against E. chaffeensis showed seroconversion (titers ranging from <1:16 to 1:256) of the paired serum samples. IgG against Coxiella burnetii, Orientia tsutsugamushi, typhus group rickettsiae, spotted fever group rickettsiae, and Anaplasma phagocytophilum were all negative. The results of the microscopic agglutination test and the isolation of Leptospira sp. were also negative.
The presence of an HME case highlights the need for further studies of the prevalence, geographic distribution, and control of this disease in Taiwan. Human monocytic ehrlichiosis patients with immunosuppressive conditions, such as diabetes, might have a higher risk for hospitalization and life-threatening complications (10). In this case, the suspicion of rickettsial infection was based on the patient’s potential exposure to arthropodborne pathogens at her workplace and home, and the patient responded quickly to doxycycline treatment. Physician awareness of HME and early diagnosis and treatment are essential to improve disease outcomes.
Dr. Peng is a postdoctoral research fellow at the Center for Diagnostics and Vaccine Development at the Taiwan Centers for Disease Control. His research interests include the epidemiology of rickettsial diseases and development of molecular detection methods for vectorborne infectious diseases.
This work was supported in part by grant nos. MOHW107-CDC-C-315-112303 and MOHW107-CDC-C-315-123110 from the Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China.
- Dawson JE, Anderson BE, Fishbein DB, Sanchez JL, Goldsmith CS, Wilson KH, et al. Isolation and characterization of an Ehrlichia sp. from a patient diagnosed with human ehrlichiosis. J Clin Microbiol. 1991;29:2741–5.PubMedGoogle Scholar
- Heppner DG, Wongsrichanalai C, Walsh DS, McDaniel P, Eamsila C, Hanson B, et al. Human ehrlichiosis in Thailand. Lancet. 1997;350:785–6. DOIPubMedGoogle Scholar
- Heo EJ, Park JH, Koo JR, Park MS, Park MY, Dumler JS, et al. Serologic and molecular detection of Ehrlichia chaffeensis and Anaplasma phagocytophila (human granulocytic ehrlichiosis agent) in Korean patients. J Clin Microbiol. 2002;40:3082–5. DOIPubMedGoogle Scholar
- Zhang L, Shan A, Mathew B, Yin J, Fu X, Zhang J, et al. Rickettsial Seroepidemiology among farm workers, Tianjin, People’s Republic of China. Emerg Infect Dis. 2008;14:938–40. DOIPubMedGoogle Scholar
- Paddock CD, Childs JE. Ehrlichia chaffeensis: a prototypical emerging pathogen. Clin Microbiol Rev. 2003;16:37–64. DOIPubMedGoogle Scholar
- Stone JH, Dierberg K, Aram G, Dumler JS. Human monocytic ehrlichiosis. JAMA. 2004;292:2263–70. DOIPubMedGoogle Scholar
- Biggs HM, Behravesh CB, Bradley KK, Dahlgren FS, Drexler NA, Dumler JS, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis—United States. MMWR Recomm Rep. 2016;65:1–44. DOIPubMedGoogle Scholar
- Tsai KH, Chang SF, Yen TY, Shih WL, Chen WJ, Wang HC, et al. Prevalence of antibodies against Ehrlichia spp. and Orientia tsutsugamushi in small mammals around harbors in Taiwan. Parasit Vectors. 2016;9:45. DOIPubMedGoogle Scholar
- Kuo CC, Lin YF, Yao CT, Shih HC, Chung LH, Liao HC, et al. Tick-borne pathogens in ticks collected from birds in Taiwan. Parasit Vectors. 2017;10:587. DOIPubMedGoogle Scholar
- Nichols Heitman K, Dahlgren FS, Drexler NA, Massung RF, Behravesh CB. Increasing incidence of ehrlichiosis in the United States: a summary of national surveillance of Ehrlichia chaffeensis and Ehrlichia ewingii infections in the United States, 2008–2012. Am J Trop Med Hyg. 2016;94:52–60. DOIPubMedGoogle Scholar
TableCite This Article
Original Publication Date: October 03, 2019
Table of Contents – Volume 25, Number 11—November 2019
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Please use the form below to submit correspondence to the authors or contact them at the following address:
Pei-Yun Shu, Vector-Borne Viral and Rickettsial Diseases Laboratory, Center for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, No. 161, Kunyang St, Taipei 11561, Taiwan; email: